Milk: Nutritional, Social, and Physiological Aspects

Transcription

Chapter 21
Milk: Nutritional, Social, and Physiological Aspects
Thou shalt have milk for thy food, for the food of thy household, and for
the food of thy maidens. King Solomon
Milk is the nearest thing we possess to a perfect aud complete food, and
no other single food can be employed as a substitute.
Harielle Chick
The production of milk constitutes the most economic method of con
verting feeding stuffs into animal products and tlie maintenance of milk
supply is the most important object of war-time husbandry.
Wright
Norman C.
21.1: Introduction. The milk problem has surprisingly complex inter
relations: energetic efficiency (Chs. 1, 2, 3, 21, 22), endocrinologic (Cli. 7),
seasonal (Ch. 8), temperature (Ch. 11), nutritional and medical (Chs. 4, 5,
G, 20, 21, 22), time relations and aging (Chs. 16, 18, 19), evolutionary, organismic and homeostatic (Chs. 7 and 10), form-function (Ch. 17), soil fer
tility and national stability (Ch. 25), and so on.
Milk production has been said to be the backbone of American agriculture
and milk consumption the keystone of American nutrition. The proverbial
vigor of the pastoral peoples is undoubtedly- associated wth their high milk
consiunption, and Americans match them in vigor.
There is one milking cow for five persons in the U. S. A. At the current
rate of milk production (5000 lbs milk per cow per year), one quart is pro
duced per capita per day. Of this one quart about half is consumed in fluid
foi-m; the remainder is used for producing butter (about 20 lbs of 4 per centfat milk for one pound of butter), cheese (about 10 lbs milk per lb cheese),
ice cream (over two quarts of milk for one quart of ice cream), evaporated
and condensed milk (2.2 lbs milk per lb evaporated milk), powdered milk (8
lbs milk per lb powdered milk), malted milk (2.6 lbs milk per lb malted milk),
and so on. The by-products from the production of butter ("defatted milk"
or skim milk), cheese (whey), and so on, are utilized as food for man, feed
for animals and for the manufacture of various products, such as casein,
lactose, confections, \-inegar, sizing, various plastics for buttons, "wool", etc.
The importance of milk is indicated by the fact that about one-fifth of the
average farmer's cash income is derived from the sale of milk and one-fifth
of the average consumer's food dollar is expended for milk and dairy products.
(The 1941 American per capita consumption was 164 quarts fluid milk, 18 lbs
792
MILK: KUTBITIONAL, SOCIAL, PHYSIOLOGICAL ASPECTS
793
butter, 6 lbs cheese, 16 lbs evaporated milk, 2 gals ice cream, and considerable
amounts of powdered milk). While the dairy industry is gigantic in the
aggregates the average dairy fann is small, typically a single-family enter
prise. Half the countiy's dairy cows are in herds of 8 cows or less, and threefourths are in herds of 15 or less (only 5 per cent of the cows are in herds of
30 to 50 cows, 2 per cent in herds of 50 to 75, and 1 per cent in herds of over
75 covs's). Daily fanning is thus one of the few remaining stable family
business enterprises; indeed, it is a way of living as well as a way of making a
living, with corresponding far-reaching implications for national stabihty
(Chs. 10, 16, 25). It is generally agreed that national welfare (health, soil
fertility, population stability) demands that eveiything should be done to
maintain a prosperous dairy industry.
While the production of pork, beef, egg, requires less human labor in pro
portion to food yield than the production of milk- the dairy cow is far more
efficient in converting cattle feed into human food than are other farm animals
in converting feed into meat or egg. The energetic efficiency of milk produc
tion in superior dairy cattle is 33 per cent, contrasted to about half this level,
17 per cent, for egg production in comparable superior fowls, and 5 to 15
per cent for meat production (Chs. 1, 3, 22, 23). The energetic efficiency of
milk production is so much greater that in spite of the greater labor cost of
milk production the current price of egg and meat is about SI. 10 per pound
of dry matter, whereas the price or whole fluid milk comes to about 50 cents
per lb of dry matter and of non-fat diy milk (dry skim milk), only 14 cents
per lb. Moreover, methods are being developed to reduce the human labor
involved for milk production by greater use of better machines and by the
use of larger animals of higher dairy merit (Ch. 22).
Furthemiore, cattle consume roughage which swne and poultiy cannot
consume and, unlike non-ruminants, synthesize by way of rumen micro
organisms complete nutrient proteins from incomplete feed protein and virtu
ally all the B vitamins (Ch. 20). The milk nutrients are thus, in part,
obtained in the nature of a windfall, from material which is otherwise nutri
tionally useless.
Dairy cuttle now consume' 91 per cent of all the silage consumed by farm animals,
53 per cent'of the hay, 38 per cent of the other dry roughages, and 38 per cent of the
1 U. S. consumers spend over
billion dollars a year for milk and dairy products,
.md the dairy industry employs (1938) "four times as many people as the railroad in
dustry, fifteen times as many as the telephone industry, nineteen times as many as
the automobile industry, and one out of every 15 U. S. families is dependent on milk
for a living." Sec Table 21.7.
2 The annual labor of milking and caring for a cow producing 5000 lbs milk, and
growing her feed,ig estimated to be 160 hours; for producinga 400-Ib beefsteer, 32hours;
for raising a 5-pig litter to 125 lbs per pig, 75 hours. On this basis, the lood-energy
return index per man-hour is 100 for the milk, 219 for the hog, and 305 for the steer;
the (ood-protein return per man-hour is 100 for milk, 98 for hogs, and 112 for beef.—
0 H. Brownlee, "Putting Dairying on a War Footing," Iowa State College, 1943.
5Jennings, R. D., U. S. D. Agr. Circular 670, 1943.
794
BIOENERGJmCS AND GHOWTII
pasture. These are feeds which cuimot be used by man or even by swine or poultry.
Dairy cattle consume only 19 per cent of the grain and other concentratefeeds. Swine,
however, consume48 per cent of all the corn or 35 per cent of all the concentrate feeds
andexccptfor about 2 per cent pasture, no roughage. Poultry consume 21 per cent of all
concentrate feeds and for about 1 per cent pasture, no roughage.
Speaking very gen
erally—the feed units are not really equivalent for dilTerent farm animals—dairy cattle
consume 34 per cent of all the feed consumed by farm livestock, beef cattle 20 per cent,
sheep and goats 7 per cent, horses and mules 14 per cent, swine 15 per cent, poultry 9
per cent. These figures give a rough idea of the relative magnitude of the dairy in
dustry from the viewpoint of use of raw material.
21.2: Nutritional importance of milk. Unlike other foods which he had to
learn to consumc, man, in common witli other mammals, is a born milk con
sumer.
Milk was evolved through the ages specifically for the nutrition of
infant mammals, for bridging the gap l)etween the dependent intrauterine
and the independent adult life (Sect. 7.2). Milk from all species contains
the same nutrients, although in different proportions. Finding milk good,
man domesticated convenient mammals for furnishing liim with milk through
out his life.
Having been developed for nourishing rapidly growmg yet delicat-e and
toothless infants, milk has unique physical and nutritional properties. Milk
is bland, soothing, fluid, yet highly nourishing; hence its use as food during
"melancholy""* and other disturl)ances, especially digestive, such as ulcer,
for which milk is often used as a virtually exclusive diet®.
Milk is commonly thought of as a "drink," but this must not lead one to
the mistaken idea that fluid milk has less solids than some "solid" foods.
Indeed, the opposite is frequently true. Thus, whereas the solid content in
fluid milk is about 13 per cent, that in turnips is only 9 per cent, in tomatoes
6 per cent, in lettuce 5 per cent. Milk is, of course, easily made "solid" by
treating it with rennet or by simple souring, both of which may be followed
by "baking." The writer recalls the pleasant flavoi-s and tastes of many sourmilk dishes partaken while visiting in the Balkans, especially in Belgrade,
where "Bulgaricus Milk," made famous by Metchnikoff as a life prolonger,
is so widely used ])y all classes of society. It is, of course, the nutrients in
milk rather than the bacteria that prolong life (see, however, Rettger" below).
Bulgaricus and other types of milk-souring destroy dangerous bacteria, thus
making the milk sale as food. Tliis is the major (oven if unconscious) reason
for the use of soured (or boiled) milk in much of Europe where hygienic con
ditions are not satisfactory and bovine tuberculosis is very common.
The nutritional importance of milk is indicated by the fact that a quart of
cow's milk a day furnishes (Table 21.1) an average man (of 70 kg or 154 lbs)
approximately all the needed fat, calcium, phosphorus, riboflavin, one-half
of the needed protein, one-fourth of the needed energy, over one-third of the
vitamin A, one-fifth of the thiamine and ascorbic acid, considerable amounts
* "Milk is especially good for them which l)e oppressed with melancholy, a common
calamity of students."—Thomas Cogan, 1584.
®Shay, H., Jour. Am. Mcd. Assoc., 120, 740 (1942).
MILK: NUTRITIONAL, SOCIAL, PHYSIOLOGICAL ASPECTS
795
of nicotinic acid and choline, and other factors, and, with the exception of
iron, copper, manganese and magnesium, which are low in milk, all the needed
minerals. (The protein in a quart of milk is roughly equivalent to that in 5
ounces of meat or fish, or 5 large eggs, or 4 ounces of American cheese, or 16
slices of bread. The energy of a quart of milk is roughly equivalent to that in
f lb of meat, or 8 eggs, or 2 lbs of potatoes.)
These estimates do not fully indicate the contribution of milk to the average
diet because of the unique supplementary value of milk to other foods (Sect.
20.4). For example, whengrowing pigs are fed only cereal,aboutSO per cent of
the cereal protein is utilized for growth; but if milk is added to the diet (liquid
milk equal in weight to the cereal weight) 60 per cent of the protein is utilized
for growth® because of the supplementary effect of the protein and other con
stituents of milk.
Dramatic results of broad social significance were reported on the supple
mentary value of milk on growth of children, especially those by Dr. Corry
Mann^. His boys were receiving a diet rated as adequate, but Dr. Mann
wanted to see what an extra glass of milk at meals (a pint per day) would do.
Records were kept of half of the group on their usual diet, and of an equal
number who received the milk supplement. The result was that while the
"control" boys gained 4 lbs in weight and 1.8 inches in height, the milksupplemented group gained 7 lbs and 2.6 inches. "The casual visitor would
never fail to recognize the boys receiving the extra milk," said Dr. Mann;
"they were obviously more fit."
The spectacular growth-accelerating effect of milk on weight and especially
on height (skeleton growth, see Fig. 21.1b) is perhaps due largely to the richness
and availability of calcium in milk. In Mann's experiments the addition of
casein equivalent to that given in milk and margarine equivalent to the butterfat in the milk did not increase the height as did whole milk. Leighton and
Clark^ found that skim milk increased growth in height as much as whole milk.
These observations lead to the conclusion that the calcium in milk is a major
factor in increased growth of the skeleton. Ordinary diets are more often
deficient in calcium than in any other nutrient, and are thus made good
by milk.
These observations on the remarkable influence of skim milk supplement on
growth suggest the need of elucidating a current problem in the dairy industry.
As previously noted, thereis enough milk produced in'theUnited States to
furnish a quart per capita per day, the optimal level of milk intake. Half
of this milk, however, is used for manufacturing butter (about 18 lbs per
, capita per year) and cheese (about 6 lbs per capita per year). The popularity
« Steenbock, H., and Hart, E. B., J. Biol. Chem., 38, 267 (1919); 42, 67 (1920); Wis.
Agr. Exp. Sta. Bull. 342, 1922.
^ See, interalia, Mann, H. C. Corry, "Diet for boys during the school age." Special
Report Series 105, Medical Research Council, London, 1926; also, Mann, J. Roy. Inst.
Pvolic Health arid Hyg., 2, 486 (1939), and Nulr. Absl. & Rev., 9, 686 (1939)-. See also
Palmer, G. T., Am. J. Pub. Health, 12,134 (1922); Sherman, H. C., and Campbell, H. L.,
J. Am. Chem., 60,6 (1924). Rose, M. S., and MacLeod, G., J. Biol. Chem., 66,847 (1925).
Orr, J. B., Lancet, 1, 202 (1928). Leighton, G., and Clark, M. L., Id., 1, 40 (1929).
Morgan, A. F., et al., Am. J. Dis. Child., 32, 655 (1926); 33, 404 (1927); 36, 972 (1928).
796
BIOENERGETICS AND GROWTH
12%-DRY-MILK BREAD
4%-ORY-MILK BREAD
12%-ORY-MILK BREAD
2
600
7
6%-DRY-MILK BREAD
BREAD
® 4C0
at ico
BREAD
4
6
8
WEEKS
6
WEEKS
Fig. 21.1a
I''ig. 21.1b
Fig.21.la to c. Plotted from data by B.W.Fairbanks,CereaZCAem., 15,169 (1938). Three
groups of 50-gra. rats were placed for 77 days on tiiree kinds of bread diets: 1, ordinary
white bread; 2, white bread containing 6 per cent dry milk; 3, white bread containing
12 per cent dry milk. In these 77 days the rats in group 1, gained 35 gni. at a food cost
of 25 gm. bread per gm. body gain; grou{) 2, gained 110 gm. at a cost of 6,6 gm. bread per
gm. body gain; group 3, gained 164 gm. at a cost of 5.2 gm. bread per gm. gain. While
the larger animals had a higher maintenance cost (because of their larger size), yet
their gains were niore economical.
MILRrNUTRlTIONAL, SOCIAL, PHYSIOWQICAL ASPECTS
797
28
/
24
BR EAO*
2
Y
/
/
y
g 16
«9
$12
o:
m
8
Fig. 21.1c.
See legend on page 796.
JY
LU
y
6?W)R1^-MILK
.0
•^•12%-DRYrMILK BREAD
11
4
1
>
4 WEEK AVCRACES
6
8
to
12/
week:>
of butter is, of course, due to its high nutritive value, its very tasty flavor,
ease of its manufacture from cream and ease of preservation. The advent of
the mechanical cream separator and the Babcock tester made it easy for the
farmer to separate cream from milk to any fat percentage, and for the buttermaker to pick up the cream for butter manufacture. The skim milk was fed
to the swine and poultry, for, as previously noted, milk, even skim milk, is an
excellent supplement to cereals normally fed to these animals.
But it is also good for man to supplement his cereal with milk, even filfim
milk; and as long as there is not enough of a given food for man, it is, usually,
wasteful to feed this food to livestock. For example, per unit dry matter,
milk is nutritionally equivalent to meat; yet when fed to animals only about
ten per cent of the milk solidsis recovered in the form of meat solids® (Ch.3).
Thus it is estimated that about 50 billion pounds of skim milk^ (about 4
billion pounds non-fat dry-milk solids) perhaps 40 per cent of the total millr
solids produced in the United States, said to be equivalent to the protein in
200 million beef steers^", is diverted from human use, and 90 per cent of it is
wasted as far as human nutrition is concerned. (There are, of course, excep
tions, as when a little skim milk may be the limiting factor in a ration for
chickens in egg production.)
More specifically, Krauss" reported that if United States millr production
were completely utilized as human food, the non-fat part of the milk would
satisfy the protein needs of 67 million persons, the riboflavin needs of 130
million persons, the calcium needs of 166million persons; but that according
to the present practice of feeding the skim inilk and whey to livestock, etc.,
only half of these nutrients are utilized for human consumption. This huge
waste of food is due to a serious misunderstanding about the nutritive value
of defatted or skim milk. Let us, therefore,discuss this problem briefly.
' 8Abbott, J. S., Am. J. Public Health, 30, 237 (1940).
®"Consumers' Guide," U. S. D. Agr., July, 1939.
"Rose. W. C.,
tein Suppl
"This
Institute,
- -
798
BIOEXERGETICS AND GROWTH
The composition of wliole milk is given in Table 21.1 in the form of a com
parison between the nutritional needs of an average adult person and the
nutrients furnished in a quart of average market milk (slightly modified from
Krauss").
Table 21.1 showsthat a quart of average milk (2.15 lbs or 4 glasses of 8 fluid
ounces each) supplies to an a^'erage moderately active man approximately
thefolloAving percentages of the nutrient standard: 150per cent of the calcium,
70 per cent of the riboflavin and phosphoms, 50 per cent of the protein, 40
per cent of the vitamm
25 per cent of the ascorbic acid^^ 20 per cent of
the calories and thiamine, 5 to 10 per cent of the iron, nicotinic acid,
and vitamin D^-.
The milk energy is seen (Table 21.1) to be equally divided between fat, 330
Calories (37 gm fat per quart) and non-fat, 330 Calories (49 gm lactose and
34 gm protein per quart). (The energy value of whey is about 270 Cal per
quart or per kg.) The milk fat thus supplies half the milk energy, the vita
mins A and D, and much of the flavor; the non-fat part of the milk, the skim
milk, supplies tlie other half of the energy, the proteins of high biological
value, calcium, riboflavm, phosphorus, iron, ascorbic acid, thiamine, nicotinic
acid, and apparentlj^ some unknown growth factors (Reed). It is thus clear
that in evaluating milk as a food, at least as much A'alue should be placed on
the non-fat as on the fat portion.
A slow transition may be taking i)lace in the dairy industry as a result of
the war and its associated world-wide food shortage'^.
Waj'S will, no doubt,
be found to save the skim milk, buttermilk, and whey for the human dietary.
'2 The vitamiii-A value of milk varies with the carotene content of the feed.
Fresh
pasture yields milk highest in vitamin A content, followed by well preserved silage,
then by hay, especially if dried by r:i))id-drying methods.—Hilton, J. II., et al., J.
Dairy Sci, 16, 355 (1935). For the influence of feeding liigh vitamin A shark-liver oil
on the vitamin A in milk, see Jensen, C., ct al., J. Dairy Sci, 26, 1931 (1943). Likewise,
the vitamin D of milk varies witli the vitamin D content in the feed as well as with
sunshine.
"There is a larye literature on the ascorbic acid content of milk.
The ascorbic
content in cow's milk is about one-sixth and the iron content about one-third of that
in woman's milk hut the riboflavin cont(Mit of cow's milk is about five-fold that of
woman's milk. Heating in copper dishes destroys ascorl)ic acid. To save ascorbic
acid in sterilization, lieat the milk to the boiling j)oint ccri/ (iiiickly (to destroy as
corbic acid o>;iilaso) then boil for tliree minutes. The ascorbic acid content of unpasteurized milk ranged from 17 to 37 mg, average 26 mg/litcr, for individual cows and
13 to 19 mg/liter in plant compositos before i)astcurizaf ion and 16 to 17 mp/litcr after
pasteurization. [C.11. Whitnah, cl al., -I. Dninj
373 (1036); 20, 9 (1937) ]. Other
reports: 20 mg ascorbic acid/liter [P. I'\ Sliarp, Science, 84, -161 (1936)1; mixed milk
before pasteurization ranged monlh to month from 14-22 (average 17.3 mg/litcr) and
after pasteurization 7.8-19.0 nig/liter l.\. II. Holmes,J. .'Imi. Diet, /issn., 15, 363 (1939) j.
Some authors claim an ascorbic acid i)cak for summer milk, others for winter milk, yet
the character of the cow's feed does not influence tlie :\scorbic acid content in milk
(Holmes, J. Xut., 17, 1S7 (1939); 26, 337 (1943) ]. The ascorbic content of human milk
varies ttith the diet, but it is ai)out 60 mg/qt. [King, C. (1., el al., J. Nut., 11, 599
0936)]. The reports vary similarly for the other vilamins. liorsook suggested that
milk should be enriched with crystalline? tliiamine as it is now frcciuently enriched with
vitamin D.
I'The food sliorlage referred to ap|)lics to most of Asia and l"]urope but not to the
United States, where mainutrition is <lue (o ignorance and economic factors rather than
to national lack of food as such.
Indeed, the 1942 agricultural production schedule
supplies protein adequate to feed 183 million persons (furnishing 81 lbs protein per
capita per year or 73 gm per capita per day), whereas there arc only 134 million persons
in the United States.
Rose, W. C., e( ai.^®
799
Instead of separating the milk on tlie farm and feeding the skim milk to live
stock, the creameries and cheese factories maj'" take the whole milk and de
velop facilities for drying the skim milk, buttermilk, and whey'®. The dry
products maj' be sold in the fomi of capsules, wafei"s, or powder, perhaps
variously flavored, on groceryshelves""', in jars, cartons, and air-tight, moistureproof envelopes. The packages could contain 4^ ounces (127 gm) solid whole
milk, each equivalent to a ciuart of fluid whole milk, or the cn\êloi)cs could
contain a fourth of this, equivalent to a largo glass of milk, or multiples of
these amounts. Wlien used for soui)s and baking, milk powder is said to
3'ield products supei'ior to fluid milk, since it is uncomplicated by the water
in the milk. The recently devclopeil food-compression machinery may be
used for tableting milk solids, whole or defatted, to be consumed direct, as the
verj'^ hard clieese in some partis of ciistern Europe is {!onsumed.
The organismic theory (Ch. 10) suggests that it would be better to consume
whole milk than any of its i)arts, because it is probalile that the various milk
constituents supplement one another nutritionally. A given amount of whole
milk has a higher phj'siologic energy value than the sum of its constituents
taken separately at different times. The fat in the milk supplcmcnis the
protein and the sugar in the milk. "It seems tliat nature lias put lactose and
milk fat together as an optimum com])ination for the yoimg animaU^."
"Lactose has an as yet unknown effect on intestinal conditions which is coun
teracted by butterfat but not by com oil." "Fortified oleomargarine did
not give growth equal to butterfat when lactose was the sole carbohydrate
in the diet. . . . Fortified oleomargarine gave growth e(iual to butterfat
over a period of 6 weeks when ... a mixture of carbohydrate (sucrose, starch,
dextrine, lactose) was incorporated."
It would, then, seem best to consume the recommended or available quart
of milk per capita per day in the form of whole milk, fluid or evaporated,
as a bread "spread" made by evaporating milk to the consistency of butter,
whole-milk cheese (inchiding the whey solids'®), or best used in bread making'®
as milk bread, and in soups-®, puddings, cakes, cookies, or in the form of a
beverage, even as recônstitut-ed milk-'.
" This is no(, a novel idea. See Eekles, C. H., cl uL, "Milk find its products," p. 201.
" Since the above \va.s written, Merrill O. Maughan (American Dry Milk Institute)
kindly sent nie an 8^-oz packaô of po\vdere<l whole milk, equivalent, to the solids in
2 qts fresh milk, which i.s hcins marketed "ox])erim(!n1 ally" in some localities for about
26 cents a jiackage (eciuivalent (o 13 cents a quart fluid milk). It is apparently less
expensive lo dehj'drate. ])ackaf;e, and market dry milk from grocery slielves than to
process and market fresh milk. ^loreover, the powdered milk keei)s for montlis. The
package had tlie following inscriptions: ".S^ ozs net. wgt, jusl add water . . . makes 2
quarts of fine iluid jnilk. . . . For best residts use wit hin sixty days of purchase." The
given analysis: 27% Initterfat, 26,8% protein,
milk sugar, 5.88% ash, 2.25%
moisture, 142 ("al per ounce (al)out 5 Cal/gm). The reconstituted milk has a slightly
cookefl taslc somewhat similar to lliat of evaporated milk.
"Hart, E. H., PJlvehjem,
A., el al., ./. J)airii Sci., 26, 429 (1943); Science, 93,
499 (1943); ./. Nnl., 26. 601 (li)43).
Velveet a cheese contains some of tlie whey solids. The composition of tlus cheese
Ia.s reported iti tiie Jour. Am. Mcd.
120, 24 (1942) ]; moisture, 43.1%; Calories per
ounce, 90; fai, 23.4'y(,; protein, I.S.4%; <'arbohydrales, 10,1% (S.4% lactose); ash,
5.3%,; calcium, 0.61%; i)ho8phorus, 0.82%,; salt, l-S'/i,; lactic acid, 1.2%.
C'f. Milchell, H. II., el nl., linken' Weekly, 114, 27 (1942); .7. NiiL, 25, 5Sr) (1943).
^"TheM.I.T, in cooperation with Uie Ho<^kefeller I'oundation and the KelloggFounda
tion developed a dehydrated milk soup containing 10% milk solids. A cup of this
soup supplies (he daily needs of all the known vitamins and minerals.
"Reconstituted milk," Nut. Rev., 1, 70 (1943).
800
While there can be no substitute for whole milk or for skim milk, claims are
being advanced by the margarine industry that oleomargarine fortified with
vitamins A and D to the butter level", flavored with diacetyl or related butter
flavor, and colored to the butter level with carotene may be acceptable to
adult consumers who cannot afford butter. The question of unsaturated
fatty acids of the linoleic acid type does not, perhaps, enter the problem,
since most vegetable fats are as rich in this type of fatty acid as butterj nor,
perhaps, does the question of"digestibility" (in adults).=3 There are, however,
short-chain fatty acids (Table 21.2) and other substances in butter not present
in other fats, and butterfat stimulates gro^vth in young rats^^' and calves''®.
As pre\dously noted, however, the superior growth on butterfat in milk over
that on vegetable oil in skim milk may be due to the supplementai-y effect of
milk sugar on butterfat^^. Milk fat seems to go best with milk sugar and
vegetable fat ^vith vegetable sugar. If butterfat goes best with the other
milk solids, it is safe to predict that a new butter "substitute" will be de
veloped in due time by the enterprising American daiiy manufacturers,
namely, whole milk evaporated to the consistency of butter, properly flavored,
and advertised for use as a "spread" in butter fashion.
The butter-margarine problem is now receiving much attention basically because
of the growth of the vegetable-oil industry and technological advances in margarine
and vitamin A production. No one argues against butter. The following statement
is generally accepted. "Our nation has grown up with butter on its bread. Butter
was eaten for its taste long before there was any knowledge of nutrition. We like
it on our hot cakes and in countless other ways for its flavor alone. Butter will always
be in demand because of its flavor and palatability. These characteristics are not
duplicated by any other fat" (Reed). But the margarine industry is pushing its prod
uct; and the broader national problem is how to avoid wasting the precious nutrients
in skim milk and buttermilk produced in buttermaking. (0. E. Reed, Chief of the Fed
eral Bureau of Dairy Industry, phrased this problem, thus: "Our dairy industry is not
operating on the most efficient basis for our national nutrition—we skim the cream
from a lot of milk and we use only the cream or the fat.") The outcome of this contro
versy between twoindustries is uncertain, but it would seem wise for the dairyindustry
to develop profitable whole-milk "spreads"" (bythe simple device ofevaporating whole
"The vitamin A content of butter is between oOOO and 20000 I.U., average 15000
I.U. per pound [Dornbush, A. C., et al., Jour. Am. Med. Assn., 114, 1748 (1940)]. The
vitamin D content of butter is 50 to 500 I.U. per pound [Wilkinson, H., Analyst,^,
17 (1939) j. At the rate of 17 lbs butter consumption per year, the vitamin A furmslied
by butter is 600to 700 I.U./day.
.
r.
-i
" For a review of the butter versus oleomargarine problem m 1942, see Uouncil on
Food and Nutrition, Jour. Avi. Mcd. Assn., 119, 1425 (1942); 118, 1469 (1942); 126, 168
(1944)
" Hart, E. B., Elvehjem, C. A., et al., J. Biol. Chcm., 122, 381 (1938); J. Dainj Sci.,
23, 181, 1201, 1205 (1940); 24, 1027 (1941).
,
^
.
28 Deuel, H. J., Jr., Science, 98, 139 (1943), published evidence to the effect that the
superior growth on milk fat is due to its superior flavor which caused the rats to con
sume more of the natural milk, and that flavoring the vegetable oil abolished the dif
ference in growth rate. The problem is evidently still in the controversial stage. See
also Deuel, el al., J. Nut., 27, 107, 335, 339 (1944). The superior flavonng, diacetyl, re
ferred to by Deuel is, however, not that of natural milk fat as consumed by infants
(rats or other species), but is bacteriologically developed by buttermakers.
» Gullickson, T. W., el al., J. Dairy Sci., 22,-471 (1939); 25, 117 (1942)
Grateful acknowledgments are made to all the author's (Dairy Department)
colleagues for stimulating discussions and for especially valuable suggestions by E. R.
Garrison and W. H. E. Reid.
Since the above was written, K. G. Weckel, University
of Wisconsin, assigned to the Wisconsin Alumni Foundation formula for a "dairy
spread" containing 56% moisture, 26% butterfat, 16% non-fat milk solids, 1% salt,
MILK: NUTRITIONAL, 'SOCIAL, PHYSIOLOGICAL ASPECTS
801
milk to the consistency of butter, perhaps adding "binder" and flavoring, and add
further to tastefulness of the product by proper publicity) and whole-milk cheeses (in-,
eluding whey solids).
The historical aspect of the nutritional importance of butterfat is generally known.
Vitamin A wasfirst discovered in milk fat^®, and the first severecases of clinicalxerophthalmia were described in children fed defatted milk®®: "The eye-sight of the children
was sold,abroad with the butter"."
Milk fat is characterized®' by a high content (7 per cent) of volatile fatty acids,
mainly butyric and caproic, with small amounts of caprylic and capric, and related
acids. This is indicated by Table 21.2®®.
Vegetable fats and blood lipoids do not
appear to contain fatty acids with less than 12 or 14 carbons. These short-chain fatty
acids are apparently synthesized by the manunary gland, as there are none in blood.
The composition of milk fat varies with season, perhaps due to seasonal differences
in the feed and also to temperature®^. The summer (pasture) milk is richer in oleic
acid, poorer in butyric and stearic, but the palmitic remains constant. This may,
perhaps, contribute to the differences in nutritive value of summer and winter millu.
The phospholipids (about 0.05per cent lecithin in average milk, 0.2 per cent in cream,
0.016 per cent in skim milk, 0.13 per cent in buttermilk, 0.07 per cent cephalin in milk)
are' not definitely related to the amount of fat. Cow's milk contains twice as much
phospholipid and four times as much phosphorus as human milk. The cholesterol
content of cow's milk is about 0.02 per cent and of butter oil 0.3 per cent; 18 per cent
of the milk cholesterol is associated with the lactalbumin rather than with the fat.
The short fatty acid and other milk-fat peculiarities may or may not be of nutri
tional significance. There are no experimental data on this question. It seems un
reasonable, however, to suppose that the mammary glands of all mammals would evolve
mechanisms for the synthesis of these short-chain fatty acids (see table below) without
serving some need.
As previously noted, fluid (market) milk contains about 13 per cent solids;
hence milk at 13 cents a quart is equivalent to one cent per one per cent solids
per quart. Assuming that a quart of milk contains 4.5.ounces (127 gm) of
solids, then at 13 cents a quart, the milk solids come to 2.9 cents per ounce
(28.3 gm) or 46 cents a pound (453.6 gm).
The market price of butterfat is about 50 cents a pound, and it has been
suggested®® that milk sugar (lactose) is worth no more than store sugar (su
crose), i.e., 5 cents a pound. This gives the milk protein and minerals a
monetaiy value of one dollar a pound. (Note: Meat protein is $1.00 a pound
when meat is 20 cents a pound; cheese protein is 90 cents a pound when cheese
is 30 cents a pound; egg protein is 75 cents a pound when egg is 30 cents a
pound; bean protein is 13 cents a pound when beans are 10 cents a pound;
white-flour protein is 10 cents a pound when white flour is 6 cents a pound®®.)
The above type of computation seems unfair because it omits the vitamins,
trace elements, and unknown factors in milk, the optimal calcium-to-phos9000 units per pound vitamin A from fish-liver oil, 3200 units per pound vitamin D
from irradiated ergosterol, also cultured buttermilk flavor and lactic acid. The mak
ing of the spread involves the use of a vacuum pan, pasteurizer, and homogenizer.
McCollum, E. v., and Davis, M., J. Biol. Chem., 15, 167 (1913). Osborne, T. B.,
and Mendel, L. B., Id., p. 311.
" Bloch, C. E., Am. J. Dis. Child., 27, 139 (1924).
®® Woods, Ruth, Borden's Review of Nutrition Research, Jan. 1943, p. 3.
Bloor, W. R., "Biochemistry of Fatty Acids," Reinhold Pub. Corp., 1943.
»» Hilditch, T. P., Analyst, 62, 260 (1937).
®® Hilditch and Longenecker, H. E., J. Biol. Chem.. 122, 497 (1938); 139, 727 (1941).
Hilditch, T. P., f. Soc. Chem. Ind., 60, 305 (1941).
Goodale, H. D., Hoard's Dairyman, 82, 316 (1937). Prentice, E. Parmlee, letter.
802
phorus ratio^®, and the unique properties of milk sugar. Unlike sucrose,
lactose passes the ileo-cecal valve and fonns in the intestine an exceptionally
favorable medium for the growth of Bacillus acidophilu^ and related acid
producers, thereby inhibiting protein putrefaction. By thus maintaining an
acid reaction in the intestine, lactose, moreover, favors maximum calcium
and phosphoms utilization (at least in the rat). It is known that (in the rat)
the ricket-producing properties of some diets arc repressed by supplementing
with lactose^®. The greater anti-rachitic value of woman's milkas compared
to cow's milk is attributed to the higher lactose content of the former.
Finally, lactosc furnishes an important building stone, galactose (1 galactose +
1 glucose ^ 1 lactose), for the neivous system.
As previously noted, milk also contains phospholipids®®—as lecithin,
cephalin, sphingomyelin, cerebrosides'—which undoubtedly have nutritional
significance.
The unique vahio of milk in the national liealth prot^ram (Sect. 20.2) consists parti(jularly in its supplementary value to the prevailing refmed-cereal-potato-sweets diet,
especially to those in the low-incomc group who cannot afford to buy meat, eggs, green
vegetables, and fruit (Fig. 21.2). The daily consumption of a quart of milk may ren
der almost adequate an otherwise inadequate diet.
A century ago, the per capita consumption of pure sugar was 8 pounds a year; now
it is over 100 (112 in 1941)". About 20 per cent of the total calories of the average con
sumer is furnished by sugar", and 30 per cent of the calories is furnished by white flour.
The milling process has been so perfected that modern white flour is almost completely
devoid of its mineral and vitamin "impurities." (The milling process removes § of the
iron, ^ of the calcium, f of the coppcr, J of the thiamine, f of the ribollavin, f of the
vitamin B comphix and nearly all tho manganese and magnesium.) The net result is a
marginal diet in which 50 per cent of the Calories are ilerived from sugar and white flour,
nearly devoid of minerals and vitamins, with corresponding marginal health". Nerv
ous manifestations associated with beri-beri and pellagra are said to be endemic in the
United States-", as are
. . among other signs and symptoms, moodiness, sluggish
ness, indifference, fear, and fatigue." The Stiebeling reports"
. . reveal a large pro-
McCollum, E. v., et al., J. Biol. Chem., 47, 505 (1921). Sherman, H. C., and Haw-
ley,E. E., id., 53,375 (1922). Sherman and Pappenheimer, A. M., J. Exp. Med., 34, 189
(1921).
Rettger, L. F., et al., "A treatise on the transformation of the intestinal flora with
special reference to Bacillus acidophiiiis," Yale Press, 1921. "Lactobacillvs acidophihts
and its therapeutic applications," Yale Press, 1935.
Bergeim, O., J. Biol. Che7)}., 70, 35 (1026). Kline, 0. h., Keenan, J. A., Elvehjem,
A., and Hart, 1*]. B., Id., 98, 121 (1932). Outhouse, .1., et al., J. Nvt., 20, 467
(1940).
Kurtz, F. l;]., and Holm, G. iO,, "Lipids of milk." J. Biol. Chem., 106, 717 (1934),
and J. Dairy Sci., 22, 1011 (1939). Ileinneman, B., "Relation of phospholipids to fat
in dairy products,"/. Dairy Sci., 22, 707 (1939). (Vane, J. C., and Horrall, B. E.,
"Phospholipids in dairy products," Id., 25, 651 (1942).
Roberts, L. J., Milbank Memorial Fund Quarterly, 17, 230 (1939).
" Lamborn & Co., sugar brokers, gave in tlieir Oct. 22, 1943, publication ("Formula
for sabotage of the sugar industry") an interesting example of "double talk" connect
ing (psychologically) the rise of Hitlerism, the decline of France, etc., with the opinion
that Americans are con.suming too much sugar. "The (nutritionists) weed is planted.
It is of the spreading variety . . . ]vventually there arc literally millions saying parrotlike "they say that you don't need any sugar. . . ."
"Vitamins and war," Jour. Am. Med. Assn., 115, 1198 (1940).
Agr.
Ward,
,
.
.
.
"Food budgets," U. S. D. A. Misc. Pub. 183, 1933; Carpenter, R. C., and Stiebeling,
"Diet to fit income," U. S. D. A. Farmer's Bull. 1757, 1936. Orr, J. B., "Food, health,
and income." Macmillan, 1936.
803
portion of poor diets in peaceful America with its bursting granaries. . . . The diets
were poor in vitamins A, D, and Bi and in calcium. . . . When white flour and sugar
provide 50 per cent of the calories . . . selection ofa diet that can be called good ... is
almost impossible except for an expert."
The dietary complications which worry physicians", food economists", and nutri
tionists" may be solved, as suggested by Sherman", McCollum", Rose", and others",
by including in the diet a quart of whole milk a day. This milk corrects the faults of
I
QUARTS
550
I
MILK EQUIVALENT
OOO
{MIRT PHODWCTS, IHCl
^LUIO UIIK)
-J150
O
m
FLUID MILK
Z3
\n
CINCLUOINC POWrRf]
2
o
u
Q.
<
u
<N
T
O-
EGGS-
ICECREAM
CONDENSED 6
EVAPORATED MILK
BUTTER^
aUID CREAM
_L_
CHEESE
1230
ISOO
1730
PER CAPITA INCOME. DaiARS
Fig. 21,2. Milk, meat, and egg consumption as related to income level. Modified
from "The Dairy Situation", Bureau of Agricultural Economics, U. 8. Dept. Agricul
ture, November, 1942.
the "perversely" used impoverished foods. Moreover, milk can be made a carrier of
the easily manufactured vitamins''^ as Bj, in the same manner as it is now often en
riched with vitamin D.
"Symposium on the fortification of foods with vitamins and minerals," MUbank
Memorial Fund Quarlcrlij, 17, #3, 1939. Contributors: Agnes Fay Morgan, Lydia J.
Roberts, W. H. Sebrell, E. M. Nelson, Alonzo E. Taylor.
Sherman, H. C., "Chemistry of food and nutrition," New York, 1938. Sherman,
H. C., and Lanford, Curoline Sherman, "Essentials of nutrition," Maemillan, 1940.
McCollum, E. v., Orcnt-Keiles, E., and Day, H. G., "The newer knowledge of
nutrition," New York, 1939.
" Rose, Mary S., "The foundation of nutrition," New York, 1938.
Brody, S., "Nutrition," Ann. licv. Bioc., 4, 392 (1935).
Borsook, H., "Vitamins," Viking Press, 1940-
804
To be sure, milk is not suitable as an exclusive diet after the normal weaning age.
The amounts of iron, copper, and manganese salts are inadequate in milk when fed
to adult rats as an exclusive diet. (The young are born with iron and copper reserves
in the liver to meet their needs during the suckling period.) But when the milk is sup
plemented by these salts, rats®" and dogs"' " may be maintained almost indefinitely
(for four generations at least) on the exclusive (mineralized) milk diet. They also
reproduced, although at a lower rate®"on this diet. Calves" were also grown on
this mineralized milk diet for at least two years, but in addition to iron, copper, and
manganese,magnesium had to be added to the milk®'. Milk is also inadequate in vita
min C when fed to species dependent on dietary ascorbic acid.
Fortunately, whole cereal (such as whole-wheat bread) supplements tlie milk defi
ciencies in a practically perfect manner (except for ascorbic acid). This was demon
strated by Sherman (Sect. 18.2.4), who maintained many generations of rats on an ex
clusive whole milk-whole wheat (and salt) diet. Sherman had two diets differing in
the mllk-to-wheat ratios: (1) i dry whole milk and | whole wheat; (2) § dry milk and
f wheat. In comparison to a good stock diet, the rats on diet (1) performed satisfactorily in growth, health, reproduction, and longevity; on diets (2) they performed ex
cellently in growth, health, and longevity. The most striking observation is that the
rats on diet (2) matured earlier, lived longer and retained their vigor to a more ad
vanced age. This result leads to the tentative conclusion that a whole milk-whole
cereal diet (supplemented in the case of man with raw cabbage or raw or canned tomato
or citrus for vitamin C) in which milk furnishes about J to J of the Calories (as when a
daily quart of milkis consumed) is nutritionally complete. Taylor" suggested the com
bination of milk and bread into a milk-bread, which is less expensive than milk and
bread. It seems agreed that most people are alike in needing milk; unfortunately,
they are not alike in their ability to get it, and the basic problem is how to bring it
within their means (Fig. 21.2).
21.3: Composition of milk. This section is not concerned with the details
of the chemical composition of milk on which there are extensive reviews®®,
but with some of its general features.
Bunge®® suggested that the chemical composition of milk in different spe
cies is correlated with the clieraical composition of the new-born animal.
This correlation, if any, does not appear to be striking. More strUcing is the
parallelism between milk composition and maturing speed of the new-born
Richardson, L. R., and Hogan, A. G., J. Nut., 19, 13 (1940).
" Elvehjem, C. A., et al., J. Nul., 20, 433 (1940).
62 For extensive reviews sec Herman, H. A., Univ. Mo. Agr.Exp. Sta., Res. Bull.
245, 1936. Savage, E. S., and McCay, C. M., J. Dairy Sci., 25, 595 (1942). Krauss,
W. E., Ohio Agr. Exp. Sta. Bull. 477, 1931.
" Duncan, C. W., Huffman, C. F., and Robinson, C. S., J. Biol. Chem., 108, 35 (1935).
Wise, G. H., Gullickson, T. W., and Peterson, W. E., J. Dairy Sci., 22, 573 (1939), and
23, 997 (1940).
"Tavlor. Alonzo, Jour. Am. Med. Assn., 81, S92 (1923).
culture, U. S. D. A., Washington, 1939. Reviews by C. A. Gary, el al., p. 649, and I.
P. Earle, p. 501. Biennial Reviews of the Progress of Dairy Science in the J. Dairy
Reserach, U. S. D. A.: Farmers Bull. 1359, 1923. Geiling, E. M. K., el al., J. Miol.
1929.
Other references are cited in the text.
Bunge, G., Z. Biol., 10, 326 (1S74). Bungc, G., "Physiological and pathological
chemistry," Philadelphia, 1902.
665
mammal, as exemplified by Table 21.3 mostly from Abderhalden®', who
called attention to this relation. (This table is modified and extended on the
basis of the newer literature®®.)
The relation between milk composition and maturing rate is complicated
by many factors, evolutionary and physiologic. The milk of the ass, horse,
and man is abundant in water (90 per cent) and sugar, but poor in protein
and fat. The milk of the reindeer and marine mammals is veiy concentrated.
The situation is too complex for a simple generalization, although, no doubt,
speed of growth, composition and physiologic age (Ch. 19) of the young at
birth are important factors in determining the evolutionary trend of milk
composition. The metho'd of obtaining the milk influences the apparent com
position.
It is remarkable that the composition differences are no greater than they
All milks contain the same constituents, although the proteins differ
imi^«iologically®®. Thus persons allergic to cow's milk can take goat's milk
without any ill efFects.
In spite of the quantitative differences in composition of the milk of differ
ent specics, man and most farm and laboratory animals thrive on cow's milk.
While goats (kids) make exactly the same growth per Calorie on cow's as on
goat's milk®', calves are said®° to react unfavorably to goat's milk; and while
horses (foals) are said to react unfavorably to undiluted cow's milk, they
thrive on undiluted goat's milk, although goat's and cow's milk have the
same quantitative composition. The differences may be associated with dif
ferences in permeabiUty of the digestive tract lining to some of the proteins
of goat's and cow's milk, with consequent allergic reactions®^
But even in the same species there is considerable difference in the quanti
tative composition of milk, indicated by the following cattle-breed-difTerence
data, on small groups of animals, from Overman et al.^Breed Differences in Composition of Milk (small groups of animals).
Means ot percentages of components
Cattle, breed
Fat
Protein
Lactose
Ash
Solids
Water
Ayrshire
4.1
0.68
Holstein
3.5
3.4
Jersey
Guernsey-Holstein
Average
6.2
4.4
3.9
3.8
3.7
5.0
4.9
4.8
4.9
4.9
4.9
0.73
Guernsey
4.0
6.2
3.6
3.6
4.0
4.7
Brown Swiss
13.1
13.4
14.9
12.5
14.7
13.8
86.9
86.6
85.1
87.5
85.3
86.2
86.3
4.4
0.74
0.68
0.70
0.72
0.71
13.7
Solidsnot-fat
Specific
Gravity
9.0
9.4
9.7
9.0
9.6
9.4
1.0317
1.0318
9.3
1.0326
1.0336
1.0324
1.0332
1.0330
" Abderhalden, E., Hoppe-Seylers Z. Physiol. Chem., 26, 489 (1898); 27, 356 and 408
(1899).
Wells, H. Gideon and Osborne, T. B., J. Inf. Dis., 29, 200 (1921). Nelson, J. B.,
Univ. Mo. Agr. Exp. Sta. R«s. Bull. 68, 1924.
Gamble, J. A., Ellis, N. R., and Besley, A. K., U. S. D. A. Tech. Bull. 671, 1939.
Earle, I. P., "Food and life.""
Ratner, B., Am. J. Dig. Dis. and Nut., 2, 324 (1935).
Overman, O. R., Garrett, 0. F., Wright, K. E., and Sanraann, F. P., Univ. 111.
Agr. Exp. Sta. Bull. 457, 1939.
806
BIOENERGETICS AND GliOWTH
There are, moreover, differences in composition mthin the breed as indi
cated by the following table (Overman, et al.).
Maximum and minimum percentages of milk constituents
Breed
Fat
Protein
Lactose
Ash
Solids
Water
2.9-5.7
2.9-6.5
2.9-4.6
2.6-5.7
.58-.85
.64-.99
89.4-84.2
8S.&-82.7
Guernsey
3.7-7.7
2.7-5.5
2.4-6.1
3.7-6.7
3.6-5.8
10.6-15.8
Brown Swiss
Holstein
2.6-6.0
3.3-8.4
2.7-7.5
2.6-8.4
2.4-6.5
2.9-5.8
2.7-6.3
2.4-6.5
4.0-5.7
.60-.85
.56-.86
2.7-^7
.57-.82
12.1-17.9
10.7-17.6
11.0-11.7
3.0-6.0
.58-.94
10.6-17.9
2.4-6.7
.56-.99
10.6-17.9
Ayrshire
Jersey
Crosses
All samples
11.4^17.3
87.9-82.1
89.3-82.4
89.0-88.3
89.4-82.1
89.4-82.1
Solids*
not-fat
7.2-10.4
8.0-11.4
8.2-11.1
7.8-11.9
7.7-11.1
7.9-11.7
7.2-11.9
The caloric value of milk, of course, varies with its composition, especially with its
fat percentage. Gaines suggested that milks of different fat percentage be converted
into milk containing 4 per cent fat, designated FCM, wiiich has a heat value of 750 Cal
per kg, or 340 Cal per lb. According to Gaines",
FCM = 0.4M -h 15/''
M is weight of milk and F is weight of fat, all in the same units, and FCM is milk cor
rected to 4 per cent fat (see Table 22.3 for details).
The Gaines formula is based on the following combustion values per gram of milk
constituent: 9.253 Cal for fat, 5.853 for protein, 3.693 for lactose; one kilogram of 4
per cent milk contains 750 Cal and 37 gm protein on the basis of 50 mg protein per Cal.
The ratio of jjrotein to energy is nearly constant, 43 to 49 mg protein per Cal, regard
less of the fat percentage in milk.
The combustion energy of 4 per cent goat's milk®' is virtually the same as of 4 per cent
cow's milk: 342 Cal per lb for goat's milk, and 343 Cal for cow's milk.
The ccmrrasrioB-
value of 3 samples of woman's milk was reported to be" 660, 680, and 770 Cal per liter.
It is often convenient to represent milk composition in terms of percentages of the
total solids, or the nitrogen in terms of total nitrogen, as follows*®.
Percentages in terms of the milk solids
Percentages in terms of total N
Fat
Protein
Lactose
Ash
Casein N
Albumin
N
protein N
Low-protein ration
28.6
24.8
40.5
5.5
77.5
18.2
4.2
High-protein ration
(N.R.l:2)
28.2
26.1
41.2
5.8
71.1
20.5
8.4
(N^.l:13)
Non-
Species Differences in the Distribution of Nitrogen in Milk®®
Ratio of
Nitrogen in milk as percentage of total N
.•Mbumin +
Species
Globulin
Casein N
Saanen & Toggenburg
Globulin
N
Albumin
Total
Non-
N
Protein N
protein N
Casein N
N
to
Gms. N
in 100 cc
Skim Milk
71
8.2
13.2
92
8.1
0.30
0.52
76
81
8.5
6.2
4.5
0.24
0.50
96
Human (one sample)
41
15.0
9.6
9.3
27
94
Jersey cows
0.19
1.0»
0.18
goats
Holstein cows
5.5
84
.
16
0.64
Gaines, W. L., 111. Agr. Exp. Sla. Bull. 308, 1928. Overman, 0. R., and Gaines,
W. L., J. Agr. Res., 46, 1109 (1933).
®^ Peterson, V. E., and Turner, C. W., J. Nut., 17, 293 (1939).
®® Shukers, C. F., et al., J. Nut., 6, 127 (1932).
®® Perkins, A. E., Ohio Agr. Exp. Sta. Bull. 515, 1932.
• 807
Incidentally, Perkins' table®® shows that the dietary protein level may influence
the percentage distribution of protein and especially non-protein nitrogen in the milk.
The table of Gamble, Ellis, and Gross^® shows that in terms of percentage of total
nitrogen, goats and cows have nearly the same composition, but human milk contains
about half the casein, and double the albumin, globulin, and non-protein nitrogen as
cow's or goat's milk. This may be associated with the younger physiologic age of
human infants than those of cows or goats, since the non-casein nitrogen of milk is
more closely related to blood nitrogen than is the casein nitrogen; and judging by the
composition of colostrum, tlie younger the physiologic age of the newborn, tlie richer
the milk in noncasein nitrogen.
The data of Gamble, Ellis, and Besley apparently show closer agreement in quanti
tative composition between goat's and llolstein-cow's milk than between Holsteinand
Jersey cow's milk, in spite of difTerences in mature weight, rate of physiologic matura
tion and growth, and different evolutionary history. This is also shown in the follow
ing summary of the species differences in tlie composition of milk.
Goat
Holstein cow
Jersey cow
Human®'
Rat'®
Dog8»
Fat
Protein
Lactose
Ash
Water
Ca
P
Fe
Cu
(%)
(%)
(%)
(%)
(%)
(mg %)
(mg %)
(mg %)
(mg %)
3.5
3.1
0.053
106
117
34
98
88
101
0.072
88.2
0.072
0.088
0.2
0.7
0.057
0.058
2.8
0.79
0.70
0.73
0.2
1.5
114
3.2
3.8
4.6
4.6
4.7
7.5
88.3
3.4
5.3
3.5
15
8.3
3.7
1.2
1.3
12
7.5
85.7
88
69
77
15
270
240
349
289
0.05
0.7
The rate of growth of suckling rats and human infants was almost identical per Cal
orie intake of goat's and Holstein's milk.
It is interesting to note that in spite of the enormous difTerences in the percentages
of calcium and phosphorus in the milk of cow, rat, and dog, the Ca:P ratio is 1.2, the
same in all. In human milk, the ratio is 2.3. These unusually high Ca:P ratios, rarely
found in other foods, are very favorable for calcium assimihation. Milk is thus the best
nutritional source of calcium, not only because of its richness in calcium, but also be
cause of the favorable Ca:P ratio.
•
Summarizing, tlie qualitative composition of different milks is chemically
(not always immunologically) the .same, but different in the proportions
between the constituents.
While the composition tends to vary with the rate
of maturing of the newborn animal, other factors confuse this relation.
21.4: Physico-chemical aspects of lactation. (See Sect. 7.2 for hormonal
aspects.) The concentration of some substances, such as urea'", is the same
in milk and blood; the concentration of most constituents in milk differs
from that in blood. Thus^', in comparison to blood, cow's milk contains 40
times as much sugar^- on a molar basis, and 80 to 90 times on a gravimetric
basis'®; 20 times as much fat, 14 times as much calcium, 7 times as much
67 Macy, I. G., el uL, .4/«. ./. Dis. Child., 43, 10G2 (1932).
68 Cox, W. M., Jr., and Mueller, A. J., J. Nut., 13, 249 (1937).
Anderson, H. D., et al., Am. J. Physiol., 129, 631 (1940).
" Peskett, G. R., Pioc. J., 28, 1667 (1934).
Simnis, K. S., Proo. Internat. Dairy Congr., 1931.
" Petersen, W. K., J. Dairtf Sci., 26, 71 (1942).
" Comparison of the blood and milk sugars of several species.
Blood sugar (%)
MUk8ugart(7o)
Cow
Goat Sheep Rabbit Mare
Sow
Doa
Rat Woman
0.05
4-6
0.06
4-6
0.13
4.0
0.08
3.7
0.12
3.0
0.06
4.5
0,12
2.0
0.11
7.0
O.ll
7.0
808
potassium and phosphate, 4 times as much magnesium, ^ as much protein,
\ as much chlorides, and | as much sodium. Some t3''pical milk constituents,
such as casein, lactose, and the short-chain fattj' acids, are absent in blood.
21.4.1: Osmotic pressxire and milk synthesis. In spite of the greater
gravimetric concentration of most constituents in milk, the osmotic pressure
is the same, about 6.G atmospheres, in milk and blood, indicating the same
total osmoticallyactive molar concentration. How is tliis sameness of osmotic
pressure in milk and blood maintained in the face of the differences in gravi
metric composition? Perhaps by the enzjTnatic change of osmotically active,
smaller-molecule transudates derived from blood into osmotically less active,
larger-molecule milk constituents. Thus one molecule of milk sugar is derived
from two molecules of blood sugar, or from one glucose and two lactic acid
molecules, therebj' reducing the osmotic pressure in the l>lood transudate by
^ or |. Similarly, the amino acids, phosphates, calcium ions, etc., are com
bined in the secretory cells into larger aggregates'—into casein, lactalbumin,
and calcium caseinate—resulting in an overall lower osmotic pressure.
The
osmotic pressure reduction in the transudate in the secretory cells below that
of the blood drives the diffusible substances from the blood into the secretory
cells as part of the tendency to equalize the hj'^drostatic or diffusion pressure.
Disturbance of the mammary apparatus, exemplified by mastitis, due to
engorgement of the secreting alveoli vdth fluid as result of cessation of cus
tomary milking, affects the selective action of the gland, with a resulting
tendency to equalization of milk and blood-semm constituents; this is indi
cated, for example, by increase in the pH, chloride, catalase, and globulin of
milk and decrease in its casein and lactose.
Indeed, milk from disturbed
glands is detected by its high pH, chloride, and catalase.
The rate of secretion and (to a lesser extent) the composition of milk depend
on the pressure within the* secretory alveoli. The higher the intra-alveolar
pressure, the less the rate of milk secretion and the greater the tendency of
the composition of milk to approach that of blood serum.
This statement
may be illustrated by several dramatically important applications:
(1) When the blood calcium (and sometimes blood sugar) declines below a
critical level as result of too rapid lactation (in comparison to the animal's
ability to mobilize calcium), the animal develops the typical hj'pocalcemic
and/or hypoglycemic syndrome milkfever. Death follows if this is untreated.
But if the udder is pumped full of air, both lactation and the drain of blood
calcium into the milk are stopped; indeed, some of the calcium in the milk
may be turned back to the blood, with the result that the blood calcium
(and/or sugar) attains a normal level. Thus, instead of dj-ing, the cow may
become normal in a few minutes^—an apparent miracle has been performed.
(2) Lactation may be stopped at any time by merely ceasing to milk.
The increase in intra-alveolar pressure as a result of failure to remove the
milk effectively blocks the lactation process. The applications of this fact
are evident: the more frequent and the more complete the milkings, the lower
809
the average intra-alveolar pressure and the greater the rate of milk secretion;
or what is the same, the longer the interval between milkings, the less the
milk production per unit time. This is illustrated by the declining curve in
Fig. 21.3, prepared from data secured in 1920 or 1921^\
lb.
\
\
16
.6
I 14
a
%
\
.?
J
\
12
✓
V
.6
/
<p
•>
/
I
\
&)
(
N
s,
I
/
6
12
16
20
24
28
32
36
Houps Aftep Last Milking
Pepcen^
6
12
16
20
24
25
32
36
HouPs aftep Last Milhnp
Fig. 21.3. The influence of milking frequency on the rate of milk productioQ.
(3) Unsatisfactory performance, especially rapid "drying up," in some
otherwise good dairy cows is explained^® by the failure of the cow to "let
" Univ. Mo. Agr. E.\p. Sta. Res. Bull. 96, 1926, pp. 82. For the more rccent litera
ture see Petersen.''^
"Petersen," Turner, C. W., Hoards Dairyman, 88, 685 (1943). Hammond, J..
/. Fci. Kcc., 16, 519 (1936).
'
'
810
down" her milk, with resulting continuous high pressure in the alveoli. The
"let-down" mechanism is apparently neuro-endocrine in nature. The stimu
lation (by milking) of the ner\'e endings in the teat and udder is carried to
the central nei'vous system, which in turn stimulates the posterior pituitary
to eject the oxytocic hormone into the blood; the oxytocic hormone stimulates
the muscles around the alveoli to contract and thus eject the milk. On the
other hand, when the cow is excited, adrenaline production (by the adrenal
medulla) is accelerated, thus relaxing the smooth muscles, that is, preventing
the muscles around the alveoli from contracting for milk ejection"'
The involvement of the nervous system is demonstrated by the eventual
loss of abilitj' to "let down" the milk following sNTiipathectomy'^ and by
similar failure when the animal is frightened or annoyed''^. Good dairymen,
of course, know that it is important to handle cows gently, quietly, and
pleasantly (see Sect. 10.8 for a discussion on a broader plane).
The speed of synthesis and diffusion of the various milk constituents is
dependent, among other factors, on (1) concentration of milk precui-soi-s in
the blood, which depends on food supply; (2) concentration of sj'nthetic
enzjones in the secretory cells, dependent on the genetic constitution of the
animal (altliough the immediate control of the enzyme concentration may
reside in the pituitarj^ or other endocrines, which are directly or indirectly
related to the genetic constitution of the animal); (3) intra-alveolar pressure
and the factore controlling it.
The concentrations of water, solids, and each of the solid constituents in
milk depends on the relative concentrations of each of the various enzymes in
the secretory cells. Thus if the concentration of the lactose-synthesizing
enzymes is high, relatively more lactose will be produced. Since per unit
weight lactose is osmotically more acti\'e than fat or protein, the milk will
contain more water in order to maintain the osmotic pressui'c constant. This
is probably the reason why the higher lactose concentration in the milk of
the horse, ass, and man is associated with higher water content (more dilute^®).
21.4.2: Colostrum.
Colostrum, the mammary secretion in the early stages of lac
tation, is in some respects intermediate between blood serum and normal millc, es
pecially in being rich in globulin and albumin, poor in potassium and high in sodium,
poor in lactose and high in chlorine, as illustrated by Table 21.4, computed by us from
Garrett and Overman'®. The following data on the composition of colostrum during
the first four days after calving (Fig. 21.4a) may also be of interest®®.
Ely, F., and Petersen, W. E., J. Dairy Sci., 24, 211 and 225 (1941).
Swanson, E.
W., and Turner, C. W., Id., p. 635. Turner''.
" Cannon, W. B., and Bright, E. M., Am. J. Physiol., 97, 319 (1931).
Bacq, Z. M.,
Id., 99, 444 (1932). Selye, H., Collip, J. B., and Tliompson, D. L., Endocrinology, 18,
237 (1934), and Am. J. Physiol., 107, 535 (1934). Simeone, F. A., and Ross, J. !•., Id.,
122, 659 (1938).
•® Blackwood, J. H., and Stirling, J. D., Bioc. J., 26, 1127 (1932). Grateful acknowl
edgements are made to W. R. Graham, Jr., for valuable suggestions.
Garrett, O. P., and Overman, 0. R., J. Dairy Sci., 23, 13, (1940).
®®Ragsdalc, A. C. and Brody, S., "The colostrum problem and its solution." J.
Dairy Sci., 6, 137 (1923). Nelson, John B., "Antibody transmission by colostrum."
Univ. Mo. Agr. Exp. Sta. Res. Bull. 68, 1924. Brody, S., and Ragsdale, A. C., "Time
changes in milk secretion," Id., Res. Bull. 96, 1926, p. 73.
Milking after
Milk
Solid
calving
(lbs)
Globulin
Casein
Sugar
Fat
(%)
(%)
(%)
(%)
(%)
(%)
1
2
24
3.3
4.4
2.1
18
1.6
0.90
3.4
3.1
3.3
5.3
4.6
4.4
3.5
4.5
3.5
3.7
3.9
4.8
4.6
4.5
1.16
0.95
0.89
0.85
0.82
0.83
0.81
0.80
3
10
g
12
4
13
5
6
7
16
13
18
17
14.5
14.4
14.4
14.2
14.2
14.2
3.1
2.6
0.50
0.38
2.6
0.33
2.6
2.8
2.3
0.30
0.22
4.7
811
Ash
180
> ,^00^
y
y
/
Fig. 21.4a.
Change in composition from
/
colostrum to milk.
y
/
/
\\^ ;;;;
w
As h
\ w
\
40
20
n
"Yotal
\
30M?
•N
\
=»i-t
\
Cldhii Un
0
Milkings aftep Calving
In addition to the unusually high level of protein (especially globulin),
colostrum is also very rich in vitamin A, perhaps 100-fold that in normal milk,'
and in other substanccs, such as immune bodies required by the young until
it develops its own immunity^°, and in lysozome®'. There are also consider
able post-colostral changes in the composition of milk, asindicated in Fig. 21.4.
21.4.3: Synthetic powers of the mammary gland. Since, as above ex
plained, milk contains casein, lactose, and short-chain fatty acids not found
in blood, and since the general level and proportions of the several constituents
in milk are different from those in blood serum, it follows that the mammary
gland has synthetic and selective powers. Mammary tissueslices also exhibit
synthetic powei-s in vitro. This was demonstrated especially for the synthe"Lysoômc " Arc/i. Path., 30. 1096 (1940); Meyer, Carl, Science,
99, 391 (1944); Lawrence, U. L., Id., p. 392.
BJOENERGETICS AND GROWTH
812
1
1
/I
'
r-
/ "N
_
^
20 ^
m.
%
s:
No 4
Ifeat ooag m
pco
15
V
j\
10"
F\
Mo-
3r [5
ta
Days-a -tt -16 -M -t? -» -8
-6
-4
-2
0
2
4
6
8
10 t?
'
...0 •
14 16 B 20
Fig. 21.4b. Changes in milk yield and in heat-coagulable protein with calving.
pH
m
>
M
pfissouptdata
0
10
20^405060?Oa0
90iDO
0.1 H..AU3li added
Fig. 21.4c. Comparison of buffer value, or acidity, of milk, colostrum, and blo.id.
sis of lactose from glucose®^ in vitro. It
813
long been known®^ that there is
an arterio-venous difference in the constituents going to make up milk, indi
cating that the mammary gland takes up the constituents from the blood
to make milk. However, the intermediate metabolism, the stages through
which the blood constituents pass on their way to milk, is still a virgin field
of investigation.
Fig. 21.4d. Change in composi
tion of fat with the advance of the
period of lactation. The first nu
meral on each line represents the
corresponding absolute number,
e. g., 4.0% fat.
Mt >soL PI c au
Mos. 0
Peplod of Lactation
Even the technique of drawing blood for evaluating the uptake of blood constituents
for milk production has not yet been worked out satisfactorily. Kaufmann and Magne®
assumed that the difTerence in composition between jugular blood and mammary-vein
blood represents the uptake by the mammary gland. Blackwood & Stirling®' criticized
this method especially because it overlooks the difTcrences in blood composition result
ing from differences in the rate of salivary secretion. Blackwood and Stirling®^ ob88 Weinbach, A. P., Am. J. Physiol., 109, 108 (1934), and J. Gen. Physiol., 19, 829
(1936). Grant, G. A,, Bioc. J., 29, 1905 (1935). Peterson, W. E., and Shaw, J. C.,
Science, 86, 398 (1937).
Kaufmann, M., and Magne, H., C. R. Acad. Sci., 143, 779 (1906).
" Blackwood, J. H., and Stirling, J. D., Bioc. J., 26, 357 and 362 (1932); 28, 1346
(1934).
814
tained blood simultaneously from the radial artery and mammary vein. Lintzol®®
obtained arterial blood from the heart (left ventricle), Graham from the internal iliac
artery through the rcctal wall", and also by exteriorizing tlie carotid artery®^; Maynard®®
obtained blood from the internal pudic artery through the vaginal wall; Petersen®"
Mi: sou •: da' -js
Mos. 0
4
6
6
.
K)
Stag® of Lactation
Fig.-21.4e. Changes in the composition of milk with the advance of the period of
lactation.
analyzed uptake from the blood by perfusion experiments. There are objections to
every one of these methods. Excitement of the animal disturbs the normal composi« Lintzel, W., Z. Zucht., 29B, 219 (1934).
Graham, W. 11., Jr., Jones, T. S. G., Kay, H. D., and Mclntosh, R. A., Proc. Roy.
Soc., 120B, 319, 330 (1936).
Graham, Turner, C. W., and Gomez, E. T., Univ. Mo. Agr. Exp, Sta. lies. Bull.
260, 1937.
*8 Maynard, L. A., el al., N. Y. Agr. Exp. Sta. Mem. 211,1938.
Petersen, W. E., el al., J. Dairy Sci., 24, 139 (1941).
MILK: NUTRITJONAL, SOCIAL, PHYSIOLOGICAL ASPECTS
815
tion of the blood, especially the blood-sugar level. Anesthetizing the aniraapo may
overcome this difficulty but introduces others.
To be useful for quantitative interpretation, measurements of arterio-venous dif
ference in blood composition must be accompanied by measurements of the rate of
blood flow through the mammary gland. Graham" employed the tliermostromuhr
metliod®^ for this purpose.
The earlier data of Graham'® et al. and also of Shaw and Petersen"* (computed on the
basis of calcium intake) indicate that about 400 volumes of blood pass through the
udder in producing one volume of milk. This means that 20,000 pounds of blood pass
through the udder in producing 50pounds of milk. Graham's thermostromuhr method,
however, gave much lower values®'.
21.4.4: Milk-sugar production. Graham reported that milk sugar is de
rived not only from glucose but also from lactic acid®® and from blood pro
tein . Some lactose may also be produced from glycoproteins'®.
These results are important because they demonstrate that: (1) blood
sugar is not the only source of milk sugar; (2) lactic acid, an important rumenfermentation product, may participate in and accelerate lactose formation—
and, therefore, milk secretion—in ruminants; (3) high dietary protein may
stimulate milk secretion; (4) the mammary gland resembles the heart, liver,
and other organs in normally utilizing lactic acid for functional activity.
It is believed that blood-sugarlevel is at least one of the major limiting factors
in milk secretion; the production of lactose by the mammary gland is believed
to control milk volume: 18 lbs of water goes with 1 lb of lactose. Anything
which reduces blood sugar (as phlorizin) reduces mostly the milk secretion
rate"'' rather than concentration of sugar in milk, although there may also
be a reduction in the lactose level of the milk®®'Alimentary hyperglycemia is, however, without effect; the excess sugar is simply excreted.
21.4.5: Milk-protein production. It is known that there is less nitrogen
in mammary-venous than in arterial blood^"\ It is not known, however,
»»lleineke, E. P., el al., Am. J. Physiol., 132, 535 (1941).
" Graham, J. Biol. Chem., 122, 1 (1937).
"2 Herrick, J. F., and Balclcs, E. J., Physics, 1, 407 (1931).
" Graham, et al., Proe. Hoy. Soc., 120B, 330 (1936).
" Shaw, J. C., and Petersen, W. E., Am. J. Physiol., 123, 183 (1938).
Computation example: if the arteriovenous difference for calcium is 0.31 mg %
and the milk calcium i.s 120 mg %, the ratio of volume blood flow through the mammary
gland to the amount of milk secreted is 120/0.31 = 387.
For fat: if the arteriovenous
difference, 11.6 mg. % is divided by milk fat content, 400 mg %, it yields a ratio of
344. For lactose: the ratio of milk sugar to blood sugar -|- lactic acid = 4860/12.4 =
391 volumes of blood to 1 of milk produced. Graham's stromuhr method yielded the
ratio 140 to 223 in milking goats and 400 in an almost dry goat.
»«Graham, W. II., .Jr., J. Biol. Chem., 122, 1 (1937). See also Shaw, J. C., et al.,
Proc. Soc. Exp. Biol. and Mod., 38, 579 (1938).
Graham, Houchin O. B., and Turner, C. W., J. Biol. Chem., 120, 29 (1937).
lleineke, E. P., Williamson, M. B., and Turner, C. W., J. Biol. Chem., 138, 83
(1941).
Gowan, J. W., and Tobey, E. F., .7. Gen. Physiol., 15, 45 and 67 (1931-2). Brown,
W. Tl., Petersen, W. E., and Gortner, J. Dairy Sci., 19, 147, 177, 243 (193^.
100 Overman, O. R., and Wright, K. E., J. Agr. Res., 36, 637 (1929). Petersen, W. E.,
et al., J. Am. Vet. Med. Assn., 79, 217 (1931).
>01 Gary, C. A., J. Biol. Chem., 43, 477 (1920). Blackwood, J. H., Bioc. J., 26, 772
(1932).
810
BIOENBRGETICS AND GROWTH
to what extent each of the various nitrogen compounds in blood is transformed
into the various nitrogen compounds in milk. The difference in amino acids
in the arterial and venous bloods is not sufficiently great to account for the
milk proteins'"^, especially as amino acids are also used in production of lac
tose. Incidentally, the production of lactose from amino acids, of course,
involves deamination and urea production, so that the mammary venous
blood contains 3 per cent more urea (1 mg per cent more) than arterial blood.
Indeed, the increase in urea nitrogen in the mammary vein may be equivalent
to the amino-nitrogen taken up by the gland to produce milk protein^°^
These masking effects and other complications make it difficult to inteipret
the significance of simple arterio-venous nitrogen differences. It is now
believed®''that blood globulin, including glycoprotein, is taken up by
the mammary gland. There are many data which bear on but do not clarify
the problem of milk-protein synthesis, such as that there is much more
globulin inlactating than innon-lactating gland tissue"^ and that mammarygland tissue contains considerable arginase"® (enzyme for splitting urea from
arginine).
Summing up, Graham el
seem to have demonstrated that only about
40 per cent of the milk protein is derived from blood-serum amino acids, the
remainder comes from blood-semm globulins and unidentified nitrogen com
pounds. This result was confirmed by Shaw and Petei*scn'", and othei-s^"®.
21.4.6: Milk-fatproduction. Meigs'"^ etal.reported a jugular-mammai-y vein
difference in lipid phosphorus, and so concluded that milk fat is derived from
blood phospholipids. Subsequent investigators"" however, found no arteriovenous differences in phospholipids, but differences in total fatty acids, and
so concluded that milk fat is derived from neutral fat, perhaps almost exclu
sively from blood fat.
The respiratory quotient is ordinarily a good index of the nature of the
metabolites involved in a given transformation (Ch. 12). Thus an R.Q. of
1.0 indicates that carbohydrate is oxidized; and R.Q. above 1.0 indicates that
fat is synthesized. R.Q. measurements of the mammary gland at Missouri^^^
yielded values considerably above 1.0 (average of 1.36), indicating synthesis
of a portion of the milk fat from blood carbohydrate. The R.Q. values
1"' Graham, W. R. Jr., et al., Arn. J. Physiol., 122, 150 (1938) and J. Biol. Ckem., 122,
275 (1938). Reineko, E. P., et at., Uiiiv. Mo. Agr. Exp. Sta. Ros. Bull. 296, 1930; J.
Boil. Chem., 138, 83 (1941).
Shaw, J. C., and Pctersen, W. E., Proc. Soc. Exp. Biol. and Med., 38, 632 (1938).
Jackson, S. M., and Gortner, R,. A., J. Biol. Chem., 123, 719 (1938).
Shaw, J. C., and Petersen, W. E., Proc. Soc. Exp. Biol. and Med., 38, 631 (1938).
1®® Graham, Peterson, V. E., Houchin, and Turner, J. Biol. Chem., 122, 275 (1938).
Shaw, J. C., and Petersen, W. E., Ptoc. Am. Physiol. Soc., 59th Meet., p. 183 (1938).
Reineke, E. P., et al., Univ. Mo. Agr. Exp. Sta. Res. Bull. 296, 1939.
Meigs, E. B., Blatherwick, N. R., and Gary, C. A., J. Biol. Chem., 37, 1 (1919).
Blackwood, J. H., Bioc. J., 28, 1346 (1934). Lintzel", Graham®®, Maynard®®
and J. Biol. Chem., 92, 263 (1931); Shaw and Petersen" and./. Dairy Sci., 23,1045 (1940).
Graham, W. R., Jr., Houchin, O. B., Peterson, V. E., and Turner, C. W., Avi. J.
Physiol., 122, 150 (1938).
817
ranged'^2
above unity in the lactating mammary gland of goats, to
0.8 in non-lactating, indicating synthesis of milk fat, especially short-chain
fatty acid fats, from blood carbohydrate. It is, however, more generally
believed'^' that the short-chain fatty acids in milk are derived from longchain fatty acids, perhaps from breakdown of oleic-acid fats, in blood"\
There is a considerableliterature on the qualitative influence of the dietary
fat on milkfat"®. Broadly speaking, such characteristics as the iodine num
ber or hardness of the butterfat tend to parallel within certain limits the
corresponding characteristics in the dietary fat. One observer reported that
18 per cent of dietary oil \vas recovered imchanged in the milk"^ However,
most milk fat is synthesized by the mammary gland, since the chemical
composition of milk fat as a whole differs from body and food fat. One of
the important contemporary problems in lactation research is the elucidation
of the paths, time rates, and mechanisms of these and related transfoimations.
The method of tagging dietary constituents with isotopes, such as with
deuterium"®, radioactive iodine"' and sulfur, heavy carbon^^° and nitrogen
.should prove helpful in tracing dietary carbon, hydrogen, sulfur, and nitrogen
to milk carbon, hydrogen, sulfur and nitrogen"^. The use of isotopically
labelled compounds is undoubtedly the next stage in the study of the inter
mediate metabolism of milk secretion. Unfortunately, this method is not
suitable for experiments with ruminants.
21.4.7: Influence of dietary fat level and of fasting on milk and butterfat
production. About a century ago Lawes and Gilbert^-- demonstrated massive
conversion of dietary carboh3-dratc into body fat in farm animals, and about
a half century ago Jordan and Jenter'^® similarly demonstrated massive
Reineke, E. P., Stonecipher, W. C., and Turner, C. W., Am. J. Physiol. 132, 535
(1941).
Reineke, el al. feel that if the milk fat all comes from blood fat, there should be
no decline in short-chain fatty acids during fast when less blood sugar is available for
fat formation. Fasting reduces the R.Q. of the lactating mammary gland to 0.8 and
also reduces short-chain fatty acids, which accords with the expectation if the shortchain fatty acids are derived from blood lactic acid or glucose.
I" liloor", Petersen"', Hilditch, T. P., and Thompson, H. M., Bioc. J., 30, 677 (1936).
Hilditch and Longenecker, H. E., J. Biol. Chem., 122, 497 (1038).
Eckles, C. H., and Palmer, L, S., "Influence of plane of nutrition on the cow upon
the composition and properties of milk and butterfat: Influence of overfeeding." Univ.
Mo. Agr. Exp. Sta. Res. Bull. 24, 1916. Influence of underfeeding. Id., Res. Bull.
26, 1916. "Influence of feeding cottonseed products on the composition and properties
of butter." Id., Res. Bull. 27, 1916. Bloor^', Maynard, L. A., et al., J. Dairy Sci.,
19, 49 (1936). Anderson, W. E., and Williamson, H. H., Phyaiol. Rev., 17, 335 (1937).
Buschmann, cited by Bloor^'.
Schoenheimer, R., and llittenbcrg, D., Physiol. Rev., 20, 218 (1940).
Aylward, F. X., Blackwood, J. II., and Smith, J. A., Bioc. J., 31, 130 (1937).'
Carson, S. F., et al., Science, 92, 433 (1940).
See also, Schoenheimer, R., "The dynamic state of body constituents," Harvard
University Press, 1942. Borsook, H., et al., Proc. Roy. Soc., 118B, 488 Q935), and Ann.
Rev. Bioc., 12,183 (1943). For the conversion of amino acids to carbohydrate, see Olsen,
N. S., ct al., J. Biol. Chem. 148, 611 (1943), and Gurin, S., and Wilson, D. W., Fed.
Proc., 1. 114 (1942).
"2 Lawes, J. B., and Gilbert, J. H., Trans. Roy. Soc., 2, 493 (1859).
Jordan, W. H., and Jenter, C. G., New Yoric Agr. Exp. Sta. Bull. 132, 1897: Bull.
197, 1901.
818
conversion of dietary carbohj'^drate into milk fat in cattle. However, a
certain ambunt of dietary fat is desirable for optimal production of body fat
or milk fat. Thus Maynard'^^ and associates demonstrated that dairy ani
mals fed a hay-silage-grain ration' containing 6 per cent fat produce above
those fed a ration containing0.7 per cent fat; and cows fed a ration containing
5 per cent fat produce above those fed a ration containing 3 per cent fat :
"For feeding practice, it is tentatively concluded that a level of 4 per cent
fat in a grain mixture, which is fed at the rate of 1 lb for every 3 to 3^ lbs of
milk along with an adequate amount of hayand corn silage, may be considered
as substantially adequate." More recently Maynard'"^ and associates re
ported that cows fed a ration containing 7 per cent fat producc 4.4 per cent
more milk, 2.0 per cent more fat, and 4.1 per cent more FCM (milk reduced
to a 4 per cent fat basis) than cows fed a ration containing 3 per cent fat.
Feeding grain mixtures ranging from 2.7 to 4.9 per cent fat did not affect
the milk or fat yield in milk cows'"^. Most of the literature^^® is not so
clear-cut because of complicating experimental factors which are difficult to
interpret. For example, the milk yield may be limited by the animal's
capacity to handle bulk, and since a fat-rich ration has less bulk per calorie,
the animal may be able to consume more available calories in the diet in the
high-fat ration than in the more bulky fat-poor ration and, therefore, yield
more milk on the high-fat ration. This is evidently not a fat effect but a
bulk effect. Replacing the bulky roughage by iso-caloric quantities of fat-
poor grain might have a similarly stimulating effect on milk production.
The feeding of cod-liver oil lowers the milk fat'"'' (the depressing factor
was traced to the triglyceride factor, not the non-saponifiable factor ) with
out, however, affecting the blood lipoids."'
Broadly speaking, while reducing a dietary or blood constituent below a
certain level lowers the milk yield and often lowers the concentration of this
constituent in the milk, the opposite effect, namely, raising the dietary or
blood constituent above a certain level, is usually without effect on milk
yield or milk composition.
For instance, decreasing blood sugar by insulin or phlorizin decreases milk
yield; but increasing blood sugar above the normal level does not influence
Maynard, L. A., et al., Cornell Uiiiv. Agr. Exp. Sta. Bull. 543, 1932; 593, 1934.
"'Maynard, et al., Cornell Uiiiv. Agr. Exp. Sta. Bull. 727, 1939. Gibson, G., and
Huffman, C. F., Mich. Agr. Exj). Sta. Quarterly Bull. 24, 1939.
>"Maynard, et al., Cornell Univ. Agr. Exp. Sta. Bull. 753, 1941.
Monroe, C. F., and Krauss, W. E., Ohio Agr. Exp. Sta. Bull. 644,1943.
1" See,for example, Allen, N. N., J. DairijSci.,17,379 (1934) (feeding fat, especially
butterfat, to cows increases the fat percentage in the milk, but only for about a week.
Feeding additional fat to cows on a high-fat level does not increase the fat percentage
in milk). See also McCandlish, C., and Struthers, J. P., J. Dairy Res., 6, 303 (1935).
Garner, F. H., and Sanders, H. G., J. Agr. Sci., 28, 35 (1938).
Golding, J., cl al. [Bioc. J.,20, 1306 (1926)] discovered a 30% decline in the fat
content of the milk on daily feeding over 56 gm cod-liver oil. This was confirmed by
many investigators.
McCay, C. M., and Maynard, L. A., J. Biol. Chein., 109,29 (1935).
Williams, H. H., and Maynard, L. A., J. Dairy Sci., 17, 223 (1934).
i3» Petersen, W. E., and Boyd, W. L., Proc. Soc. Exp. Biol. and Med., 37,537 (1937).
819
the lactose per cent in milk or the milk yield. Likewise, decreasing the pro
tein content below about IG per cent in the ration of milking cows may
depress milk yield; but increasing it above this level does not increase milk
yield or change the composition. However, some diffusible constituents in
milk not s>Tithesized by the mammary gland, such as vitamins A and D,
may be increased enormously above the normal level by their dietary or
blood increase.
Related to tiie problem of dietary level is that of fasting on milk production and
composition. As expected, continued fasting lowers the milk yield; but unexpectedly,
it raises the concentration of most milk constituents (fat, protein, ash, total solids),
though it lowers some, especially lactose. Figs. 21.10 and 21.11 indicate how the per
centages of the various milk constituents change with advancing fast. The nature of
the changes varies with the time of fast, stage of lactation, individuality of the animal,
nutritive condition and so on.
These time changcs for 6 days (144 hours) in milk yield and composition do not
precisely reflect (oxce|)t possibly in the sugar) the quantitative time changes in the
composition of blood, jis illustrated by the following data>" on blood. Tlie important
effect of fasting on lactation may bo by way of the influence on the lactogenic hormones,
which influence lias not yet l)een investigated.
Thefollowing comparisons, modified from Smith"®, ona lactating Ayrshire cow indi
cate a similar lack of correlation between milk and blood composition.
<4
Before fast
5th day fast
10th day fast
Blood
Miik
scrum
phospha-
phospha-
tase
tase
units
units {%)
(%)
4.7
3.0
35
145
4.1
141
N partition in milk as % of
Blood
Serum
C1
(mg %)
350
347
337
total N
Milk
C1
(mg%)
Casein
100
107
128
78
75
74
/
albumin
+
Non-
globulin prolcin
15.0
17
19
6.5
7.0
7.0
Blood
Serum
Ca
Protein (mg %)
93
10.5
93
93
9.8
10.2
Corpus
cular
volume
(%)
32
40
41
As previously noted, the nature of the diet changes to some extent the composition
of the milk fat. The advance of the period of starvation changes the nature of the
nutrients available for the mammary gland, and consequently changes to some extent
the nature of the milk fat. Thus the iodine values rise (from37 to 53) and the ReichertMeissl value declines (from 25 to 9) during fast'^".
Summarizing this section as a whole, milk is produced in the secretory cells
of the mammary gland in several steps, fii-st by filtration, then by synthesis
of the major transudate constituents into larger molecules, such as lactose,
from glucose and from lactic acid. Such synthesis of onelarge molecule from
several smaller ones produces an osmotic-pressure gradient, forcing more
blood transudate into the secretoiy cells. The rat« of milk production is
dependent on several factors: (1) the i-ate of synthesis in the secretory cells,
See, among others, Harrison, E. S., and Savage, K. S., Different pianos of protein
intake and milk production. N. Y. (Cornell) Agr. Exp. Sta. Hull. 540, 1932, and Bull.
Oio, 1933.
Aylward, F. X., and Blackwood, J. H., Bioc.
30, 1819 (1936).
Smith, J. A. li., Ilowat, G. R., and Ray, S. C., J. Dairy lies., 9, 310 (1938)
Smith, J. A. B., and Daatur, N. N., Bioc. J., 32, 1868 (1938).
820
(2) the concentration of milk precursor in the blood, and (3) the rate of blood
circulation through the mammary gland. ]\'Ieasurements of mammary
arterio-venous differences in blood composition indicate that: (1) milk sugar
is normally produced from (a) blood sugar, (b) lactic acid, (c) protein; (2)
milk protein is produced from (a) blood amino acid (up to about 40 per cent),
(b) blood-serum globulin and unidentified substances; (3) milk fat from (a)
blood-semm fat (or equivalent), (b) blood sugar and possibly blood lactic
acid and protein.
Reducing blood sugar or other constituents below their normal levels de
presses milk production and reduces the percentage of its constituents; but
increasing blood sugar orother blood constituents above their normal le\els
does not usually increase milk production, or the percentage of sugar, fat, or
protein in the milk. For instance, adding fat to a cattle ration alieady con
taining 4 per cent fat does not appreciably increase the fat percentage in
the milk.
Some difTusible substances not sjTithesized by the mammary gland, such
as iodides and some of the vitamins, tend to enter the milk in some pi'oportion
to their concentration in the blood. In this way cow's milk may be enriched
in these substances by dietary methods, e.g., with vitamins A (from 400 units
per quart on winter feed to 2200 on green summer pasture), with vitamin D
(from 5units per quart inwinter light to 50 units in summer sunshine and 160
on feeding about 200 gm or lb irradiated yeast per day), or vath iodide
(Ch. 6); it cannot, however, be enriched appreciably with calcium, iron,
copper, or thiamine, (human milk apparently can be enriched with thiamme
by dietary means^").
The operation of the law of diminishing returns (Ch. 1) relating the con
centration of milk and feed constituents may be illustrated by the following
values on the relation between vitamin D in milk and feed.
Vitamin D units fed to cows 0 600 1400 40000 6Q00Q
Vitamin D units per quart milk 3 5
10
20
30
There are large bodies of data on such relations by the Ohio and Wisconsin
workers and others.
21.5: The heat increment of lactation during feeding and fasting. As
might reasonably be expected, the lactation process involves an extra energy
expense or heat increment above the non-lactating level. The milk piecuisoi*s
are assembled and synthesized into milk; the lactating mammary gland has
more physiologically active tissue; the endocrine system (especially thyroid
and pituitary) is physiologically more active during lactation; two to three
times more food is ingested during lactation (Fig. 14.20c). Each of these
processes involves some form of "work" (Chs. 2 to 5), which, of course,
takes place at an energy cost. We shall indeed demonstrate that the heat
Donelson, E. G., and Macy, I. G., J. Nut., 7} 231 (1934).
821
production during heavy lactation is about 100 per cent above that during
the non-lactation level in spite of the following conclusion to the opposite:
.. lactation does not increase the heat production. This is not strange,
since the arrangement of food materials in the preparation of milk depends
upon the hydrolytic cleavages and syntheses which involve hardly any thermal
action*®®." This conclusion*®®, generally quoted in textbooks, is based on
heat production under basal conditions, that is heat production during fast,
RAT 9420
GESTATION
« LACTATION
POST-LACTATION
(4 LITTERS).
LOG. SCALES
«90
200
BODY WEIGHT
Fig. 21.5a. The influence of lactation on heat production. The smooth lines repre
sent heat production of non-lagtating animals (the lower line for mature animnlg of
different species, the upper line for rats of diflferentsize assuming, the same 0.73 slope
of the line).
and we shall show that fasting depresses lactation and heat production.
Under ordinary conditions, of course, lactating animals do not fast; indeed,
they consume two or three times as much food as non-lactating ftrn'mals
(Fig. 14.20c). As aforenoted, their heat production is perhaps twice as
Lusk, G., "The Science of Nutrition," Philadelphia, 1928.
822
BIOEXEHGETICS ASD GROWTH
great as that of non-lactating animals, the oxact vahie deiJcnding on the
lactation level, and therefore food intake. ]-et us clai'ify this statement by
analyses of data.
21.6.1: The heat increment of lactation during normal feeding.
Figs.
21.5a to c show'®' that the heat production in laetating rats maj^ be 100
per cent above the non-lactating level. Fig. 21.G compares similar curves
for dairy cattle and rats (assuming that heat production/(\veight)'''" is a
comparable ratio in cattle and rats).
IMI9
'
Figs. 21.7a and b show heat produc-
111BU7
• HUD
8 BOW
jC " lOWtAHEO
HMtO
1) ICSM
lOWtAMfD
Two
12 tOKH
leWtAHED
HUp
11
>2 KKN
— liWtANED
OSOM
_ oWEANCD
5
iO 23 )0 40
lO
GESTATION 6
To
30 40
1
10
23
30 40
LACTATON, [WS
Fig. 21.5b. Time curves of metji))olism with the advance of the period of gestation,
lactation, and post-lactation rest.
tion as a function of milk production in rats"" (taking the litter size in rats as
index of milk production) and goats.
\Miichever representation method is
Brody, S., lliggs, J., Kaufman, K., and Herring, V., "Energy metabolism levels
during gestation, lactation, and post-laetation rest," Univ. Mo. Agr. Exp. Sta. Res.
Bull. 281, 1938.
""Washburn, L. E., Brody, S., and llagsclale,
C., "Intiuence of fasting and refeeding on milk production," Id., Res, Bull. 295, 1939;
823
employed, the result is the same: heat production in non-fasting animals is
proportional to milk production.
The high heat increment of lactation is not due to higher physical activity
during lactation because, as shown in Fig. 14.20c, physical activity during
lactation is considerably below the non-lactating level. Fig. 14.20c also
shows that food consumption during the lactation peak is approximately
three times that of the prelactation level. The high lactation heat increment
is thus shown to be associated Avith the high food consumption and milk pro
duction rather than with physical activit3%
RAT
RRSTUTm 161
RAT 9«t9
SiOONI) um (I))
oitnuwtANco
CAL^
A
(522c
MI »«t?
THIIDUnER
*AT 9419 '
CAi/cwr
(II)
^
KXJUIHUmB tj)
Sl80
CAiyiDW
DAYSO
7
»4
GESTATION
£
§
M
21
25
LACTATION
3^
42 O
7
14
GESTATION
7
14
21
28
3>
42
LAaATION
Fig. 21.5c. The relative influence of gestation, lactation, and post-lactation rest on
body weight, and heat production per day and per (weight) " on four successive litters
of rat 9419. Note the influence of the number of young on the metabolism level.
21.5.2: The heat increment of lactation diuing fast. Depending on the
rate of milk flow, lactation may treble the food consumption of the non-
lactating state (rats"\ women"^, cattle), and it is not surprising that the
heat production is also increased.
Lusk's conclusion that "lactation does
not increase heat production" refers, on the contrary, to a post-absorptive or
fasting condition, which tends to depress, perhaps stop, the milk flow. We
propose to substantiate the statement that even a relatively short fast virtually
stops lactation in the sense of milk yield.
"I Slonaker, J. R., Am. J. PhysioL, 71, 362 (1924-5). Wang, G. H., Id., p. 736 (1925),
and Comp. Psychol. Monogr., 2, No. 6 (1923).
Macy, I. G., et aL, J. NuL, 4, 399 (1931).
RAT 9420
'
'
II RATS
9
12
IS
16
I
IS
18
DAYS
i
MOS.
LACTATION -COW
2i
24
27
LACTATION - RAT
36
'33
ARITHMETIC SCALES
ARITHMETIC SCALCS
the ratio
comparable for the two species.
Fig. 21.6. Heat production per weight"-as function of time during gestation and lactation in cattle and rats, assuming that
MOS GESTATION-COW
01234S678il234S678
DAYS GESTATION-RAT
6
® END OF LACTATION
« FOURTH LITTER 3 RATS
THIRD LITTER
SECOND LITTER 13RATS
—— FIRST LITTER 8 RATS
RAT" 9419 •
® END OF LACTATION
(S IIVINQ 3 KAD)
SECOND LITTER I2RATS
THIRD LITTER 8 RATS
—» FOURTH LITTER II RATS
(AHfR riflH DAY Of lACTATION 4 RATS
—— FIRST LITTER 10 RATS
o
o
to
i
8
1
0
00
to
MILK: NUTRITIONAL,. SOCIAL, PHYSIOLOGICAL ASPECTS
825
Let us first discuss the iniuence of fasting on the Tnillc production and heat
production in rats^®^ The change in body weight of the 10-day old litter
during a 45-minute suckling is taken as index of the litter "food intake", or
of the mother rat's milk production.
Fig. 21.8, lower curve, shows that within 10 hours after the food was re
moved from the cage, the litter "food intake" became zero; that is, the
mother's milkproduction declined to an insignificant level. In the sametime,
the mother's R.Q. declined from 1.0or over, to nearly 0.7,indicatingthat the
available carbohydrate in the lactating mother rat disappeared within 10
r-'V
•\y
^>
/
•
>
-
'/
✓
y\
*
/
✓
'
0
0
y
'
6
to
BAR IN IIIHR AT li MIS
r
80
120
160
SCO
240
200 )20 O
UniR WIGHT AT rtO«K.6MS.
to
&Q
9o
lOo
no iaq
CAW IN WKHf OF UTTER,
G1
XI-"tT"
14)
/
"S
125
\
r
7J
> C"'-
y
\
N
y
*
•
y
lU
'>
y
.
25
N
ol
0
1t
'I
I1
\
i\
•r
(
}
i0
I1
12
0
<\
RAT$ m
I\
wD
tI
UTTtR
Fig. 21.7a. Heat production as function of litter size and litter-weight gain which,
of course, tends to be proportional to milk production of mother rat and related data.
The space between the broken lines represents § of the data points.
hours after the food was removed; and the mother's metabolism declined
from about 60 to 35 Calories. The baby rats died of starvation within 4
days of the mother rat's fast. Incidentally, this chart shows that milk is not
produced at the expense of the mother's stable tissues because the mother
fasted 7 days, and recovered on refeeding, while her young died in less than
4 days. If lactation occurred at the expense of the mother's stable tissues,
lactation would continue to the end and mother and young would die at ap
proximately the same time.
It can thus be concluded that it is true that the
BIOENERGETICS AND -GROWTH
826
basal metabolism of "lactating" rats is no greater than that of non-lactating,
because under conditions of basal metabolism there is practically no lacta
tion, and consequently no heat incrementof lactation.
Fig. 21.9 shows that the parallelism holds not only for fasting but also for
refeeding. Noi-mal milk production almost perfectly parallels feed consump
tion, heat production, and R.Q.
•
*
•
A
GOATi5,
GOAT 90,
GOAT 65,
60AT90,
3-2-38
3-2-38
5-2-38
5-2-38
O-300
OMITTED FROM CORRELATION
2
6MSO
100
200
300
400
500
600
MILK PRODUCTION IN 12 MRS., X
Fig. 21.7b. Heat production per 12-hour period above the basal level plotted against
milk production during fast and refeeding of goats. The data points representing suc
cessive 12-hour periods are numbered serially. Sy.x, the standard error of Y about the
equation line (Ym a function of x), has a value of 61,whichmeansthat the heat produc
tion above basal can be estimated from the equation with the odds 68 out of 100 that the
error will not exceed 61 Calories.
-143
Similar results were obtained on goats"' (Fig. 21.10) and cattle"'' (Fig.
21.11).
Although we have no data on the influence offasting and refeeding onmilk
secretionand heat production in women, data on rats, goats, and cattle demon
strate that milk production, heat production, and respiratory quotient fall
i« Washburn, Brody, and Ragsdale"®. The curves for the goats were plotted from
original data; the curves for the cattle were plotted from data by Overman, O. R.,
and Wright, K. E., J. Agr. Res., 35, 637 (1927).
827
and lise in percentage parallel with, fasting and refeeding. Hence the con
clusion that there is a large heat increment and energy cost of lactation.
Lactation is said to begin in the later half of gestation; lactation is an out
growth of gestation (Sect. 7.2). The problem of prenatal growth and metab
olism during gestation was previously discussed (Sect. 14.7, see Figs. 14.17 to
14.23).
21.6: Energetic efficiency of milk production. The overall economy of
milk production is composed ofmanyelements, the two outstanding of which
are (1) energetic efficiency of the lactation process discussed in this section;
MOTtCR
RATWDCV
^
Of mtR ptAD
I RAT CtED
V
UTTER KAD
MX
MOTHER
"rooo wvti
v_ RAT KX IOJ2
T.XCUIS • FAST etom AT fa II Mdl-U-in
FAST-HOURS
Fig. 21.8. The course of: heat production (Cal/day and Cal/kg/day), R.Q. (respira
tory quotient) and litter "food intake", Avith time after feeding of the mother. Note the
parallelism between the R.Q. of the mother and the "food intake" of the litter.
Note
that the gain in weight of the litter during 45-minute sucklingdeclined from three gm.
to zero within eight hours after the food was removed.
(2) size of animal, "dairy merit", and plane of nutrition discussed in the
following chapter.
As defined elsewhere (Chs. 1 and 22), gross energetic efficiency of Tnillf pro
duction is the ratio of milk calories produced to feed calories consumed, including maintenance cost; net energetic efficiency is the ratio of milk calories
to feed calories above the maintenance cost.
828
Gross efficiency
of milk production
mjllk calories produced
(21.1)
feed iTDN) calories consumed
including maintenance cost
Net efficiency of
milk production
milk calories produced
feed iTDN) calories consumed
(21.2)
above the maintenance cost
RAT 1)09
RAT 2)9
MOTHER
6-4-,
,
•»-5UCKllNG ' AfTW
KUNQ AFTER
4 HOUR FAST
4
HOUR
fAST
R.a-IITTW
-RAT l)09RAT 2)9-7 YOUNG
1 YOUNG-FAST
FAST BEGUN AT . ..
DKjUN AT AQE 9
to pAY5tl-l4-)«)
60
72
CM5(l-l4-)8)
72
84 O
84
HOURS
16
24
FAST
}2
40
Fig.21.9. Theinfluence offasting and refeeding ofmother rat on hermilkproduction
(measured by litter-weight gain during suckling), metabolism, body weight, and R.Q.
Note the prompt decline in "litter food intake" and metabolism on fasting and rise on
refeeding.
If body weight is unchanged during lactation, the gross efficiency is com
puted by replacing the numerator in equation (21.1) by the milk energy, ac
cording to the method of Gaines^^^ (convert milk to FCM from Table 22.2
and multiply FCM pounds by 340, the caloric equivalent per pound FCM);
and by replacing the denominator by the TDN energy consumed (multiply
pounds TDN by 1814, the assumed caloric equivalent per pound TDN).
Equation (21.1) then becomes:
Gaines, see Table 22.3.
Gross efficiency
of milk production
340 X FCM (lbs)
1814 X TDN Obs)
829
(21.3)
In addition to the overall gross and net efficiency categories as defined
above, one may measure the efficiencies of the various component processes
as, for example, the energetic efficiency of the mammary gland alone in as
sembling the milk precursors in the blood andsynthesizing them intomilk.
Graham^"^ and associates at the Misspuri Station indeed computed the
mammary-gland energetic efficiency from the arterio-venous differences in
0)—-« PER CENT FAT
©•--•TOTAl CASEIN
( J ) ^ TOTAL PROTEIN
(4)^-TOTAL NITROGEN
(a«—• ALBUMIN t$ eiOBULIN
(6).—. nON-P(OTEIN NITI06EN
(7)-— AV.Il.a/l2HllS, ABCVE Q7
W—.CAL/«2HRS,ABCVE 'BASAL
GMS.Cf MIK
<50\T65
3-2-38
3-2-38
&
HAY—
QCATW
3-2-38
QCAT6S
GOAT90
V2-38
3-2-38
•GOAT65
'60 Bo 100 120 KtOO 20 40 60 80 100 l20 VtOO to 40 60 80XX>0
40
60 80 100
HCXIRS FAST
Fig. 21.10. Thelower half represents comparison ofthetime curves ofmilk production
(curve 9), heat production above base (curve 8), and R.Q. above 0.7 (curve 9), all in
terms of percentage of normal initial values. Note the striking parallelism of these
curves for goats and compare to the parallelism of the curves in Fig. 8 for rats. The
upper curve represents the time changes in composition of the milk with advancing fast
and refeeding.
oxygen and carbon dioxide content. They reported that the gross efficiency
of the mammary gland, including its maintenance cost, is approximately 90
per cent; that is, 10 per cent of the milk-precursor energy entering the mam
mary gland was expended for the sjnithesis of milk from its precursors, and
for the maintenance of the gland"®. Thus, for example, if an 1100-lb cow
The efficiency was computed from the ratio:
Milk energy perccmilk
jnillt yield— ^
(CO* vol.% —Oivol.%) -1-5.01 (0»vol.%)
milk energy/cc milk
roduced ranged from
I2 decrement, 5.34
Cal per 100 cc.
BIOENERQETICS AND GROWTH
830
produces 40 lbs FCM or 13600 Cal of milk, 10 per cent of this value, that is
1360 Cal of energy is wasted, i.e., given off as a heat increment of mammarygland activity. Incidentally, since the "basal metabolism" of a 1100-lb cow
isabout7000 Cal, the 1360 Calheat increment ofmammary-gland activitycon
stitutes nearly 20 per cent of the basal metabolism. It was noted in the
previous section that, the heat increment of heavily lactating animals is about
100 per cent above that of the non-lactating level.
cow II •
7TH. MONTH LACTATION
'
I
COM J42
1ST MONTH LACTATION
lOTa MONTH LACTATION
(2)..-^totai solids
(s*—•pROTUN
COW 742
'ASH
COW II
(VIo.—.«IACT0S{
(61*.
iMiU
40
iO
80
HOURS FAST
NO
OS O
.
Fig 21.11. Fasting dairy cows for 3 days (said to be the time required to attain the
post-absorptive level for "basal metabolism" in cattle) reduces imlk yield to 6-20 per
cent of the original level (depending on the stage of lactation and individuauty of the
cow). This resultsubstantiates the conclusion based on the rat and goat data that it is
not possible to measure the basal metabolism of animals yielding normal amounts of
milk because the fast required for basal metabolismprofoundlydepresses milk produotion. The uppercurves represent changes in percentage composition of milk} the lower
curves, changes in absolute yield; both upper andlower curves are represented in terras
of percentages of the initial values. From the upper curves, note that fasting, which
reduces milk yield increasesfat percentage (1) but reduceslactose percentage (6),
21.6.1; Gross efficiency of milk production in dairy cattle. Using equation
(21.3) above, we"® computed, first, thegross efficiency of milk production of
368 dairy cows (datain Table 21.7) with the results summarized in Table 21.6.
These tables show that the given cows—weighing from 1000 to 1300 pounds,
producing 28 to 50 lbs FCM and consuming 17 to 28 lbs TDN per day—proBrody, S., and Procter, R. C., "Energetic efficiency of milk production and the
influence of body weight thereon," Univ. Mo, Agr. Exp, Sta, Res, Bull. 222, 1935.
Brody, S., and Cunningham, R., la,, Res. Bull.238,1936.
831
duced milk at a gross energetic efficiency of 28 to 34 per cent; that is, 28 to
34 Cal milk were produced per 100 Cal TDN consumed. In other words,
about ^ of TDN energ}?^ consumed by the superior cows was recovered in the
milk; or the TDN energy consumed was about 3 times the FCM energj-^
produced.
Additional significant features of this table: (1) the daily FCM production was
10,000 to 17,000 Cal per day and TDN consumption 32,000 to 50,000 Cal per day; (2)
the milk calories produced were from IJ to 2 times the estimated basal metabolism of
the cows; (3) depending on the milk yield and efficiency, from J to i of the total TDN
consumed was used for maintenance, leaving from Ho § for milk production; (4) the
cows consumed 2 to 3 times as much TDN during lactation as during non-lactating
maintenance, a result in good agreement with the one previously cited for lactating
rats and also for high-milking women.
The highest energetic efficiency of milk production that we encountered (estimated
from the nomograph. Fig. 22.2) was 47.6 per cent for the Jersey champion cow Stone-
hurst Patrician's Lily, a 700-pound cow which produced 25,946 lbs FCM for the year
Much higher absolute production records were made, but at lower energetic efficiencies.
Thus the U. S. Holstein champion cow Carnation Ormsby Butter King "Daisy" pro"
duced"^ 36,476 lbs FCM per year, which is 40.5 per cent (=
((1700-700
\
\
25^9^ ^
25^946
J
above that of the Jersey champion production; but since the Holstein cow weighed
X100 j above that of the Jersey weight,
12 09
6 33
\
= — ^ ^ X 100 I
6.33
f
more TDN for maintenance than the Jersey, the gross energetic efficiency of milk pro
duction of the Holstein was computed (from Fig. 22.2) to be only 43.6 per cent in con
trast to gross efficiency of the Jersey of 47.5 per cent. This 47.5 per cent gross efficiency
value with regard to TDN is probably near the limit of biological possibility. The
detailed production records of "Daisy" are given in the following table.
Production Records of Carnation's "Daisy"
Lactation month
1
2
3
4
5
6
7
8
9
10
11
12
FCM (4% milk),
Ibs./aay
FCM, Calories/day
Estimated gross energetic
33109
35907
35074
37573
36611
34969
35000
33031
32745
31243
30603
31001
43.8
44.6
44.4
45.3
44.9
44.3
44.3
43.7
43.6
42.9
42.7
42.9
97.38
105.61
103.16
110.51
107.68
102.86
102.94
97.15
96.31
91.89
90.01
91.18
efficiency
It is significant that the gross energetic efficiency of milk production of "good"
dairy cows is of the same order as the gross efficiency of early postnatal growth on
"good" diets, namely about 30 per cent (Ch. 3). Thus chicks and cattle grow at,
roughly, the same gross energetic efficiency in early postnatal life, just as large arid
small cows tend to produce milk with equal gross energetic efficiency.
See Holstein-Friesian World, Feb. 22, 1936.
-A
832
It will bepresently shown that the net energetic efficiency of milk production with
respect to TDN consumption in dairy cattle is of the order of 60 per cent. Since nei
efficiency does not include maintenance cost, therefore gross efficiency, which does in
clude maintenance cost, can never reach the net-efficiency of 60 per cent level; 60%
is probably as high a gross efficiency level with respect to TDN consumption as it is
possible to achieve.
21.6.2: Gross efficiency of milk production in dairy goats. Theefficiencies
of seven goats were investigated"'. Their weights averaged 42.5 kg (93.5
lbs); daUy milk production 2114 Cal, or 6.2 lbs FCM; gross efficiency of n^
production with respect to TDN ranged from 32 to 40 per cent, averaging
34.9 per cent. The conclusion follows that the gross energetic efficiency of
milTf production in dairy goats is of thesame order as that of dairy cattle.
It is significant that women, in the same weight class with goats, produce
Tnillf at the same level and at the same gross efficiency as goats. Thus wet
nurses were reported to produce 4.5 liters (about 10 lbs) per day , and 3.1
Uters (near 7 lb or 2100 Cal) milk per day^®°. These women"® converted 30
to 50 per cent of the food calories to milk calories, confirming Hoobler"\
who observed women converting from 41 to 47per cent oftheir dietarycalories
into milk, that is, producing milk at a gross energetic efficiency of 41 to 47
per cent.
21.6.3: Gross efficiency of milk production in rats. There is some difficulty in
obtaining the milk-energy production in rats. However, we"^ are confident of the fol
lowing results because they represent concordant values obtained by two methods as
follows:
(A) The milk produced in the rat was estimated from the weight gains of the litter
during timed suckling intervals, corrected for weight losses due to urination, defeca
tion, and insensible perspiration:
Gain in litter weight (gm) during
Calories
suckling plus loss in litter weight X per gm
Gross efficiency
of milk produc- =
insensible perspiration
rat milk
Calories TDN consumed by mother
tion in the rat
The caloric value of rat milk was estimated from its composition. We assumed, on
^the basis of data by Mayer"®, and by Cox»", that rat milk contains 16 per cent fat, 12
per cent protein, 3 per cent carbohydrate; therefore, a gram ofrat milk has a combus
tion value of 2.3 Cal (9.5 X 0.16 -H 5.6 X 0.12 -1- 0.03 X 4 = 2.3).
(B) The milk produced in the rats was also estimated from the energy stored in the
litter, plus maintenance of the litter.
"8 Brody, S., Sandburg, Mrs. Carl, and Asdell, S. A., "Growth, milk production,
energy metabolism and energetic efficiency of milk production in goats." Univ. Mo.
Agr. Exp. Sta. Res. Bull. 291, 1938.
, «
r rv-
on ttoo
Ylinen, L., Acta. Paediat., 21, 473 (1937). Macy, I. G., J. Dts. Child., 39, 1186
(1930).
Shukers, C. F., ef ai.,/. iNTuf., 6, 127 (1932).
Hoobler, B. R., Am. J. Dis. Child. 14, 105 (1917); Jour. Am. Med. Assn., 69, 421
Brody, S., Nisbet, R. N., "A comparison of the amounts and energetic efficiencies
of milk production in rat and dairy cow." Univ. Mo. Agr. Exp. Sta. Res. Bull. 285,
1938.
»» Mayer, D. T., /. Nut., 10, 343 (1935).
Cox, W. M. Jr., and Mueller, A. J., J^. Nut., 13, 249 (1937).
833
h
uuuEsa
DATA-A
-lOOO
LACTATION
Fig. 21.12a. Milk production and energetic efficiency of milk production in rats in
relation to stage of lactation, litter size, litter weight, food intake of mother rat, and
litter metabolism. The energetic efficiency of milk production was obtained by two
methods, method A (Fig. 21.12a), method B (Fig. 21.12b), and by both methods, A and B
(Fig. 21.12c). Note that the rats produced 15 to 115 Cal. (av. 60 Cal.) milk per day, and
700-1400 Calories during the 21-day lactation period; that the mother rats consumed
70-220 Cal. TDN per day, depending on litter size (milk production). The numbers in
parenthesis represent number of rats in litter. Fig. 21.12c compares the results obtained
by methods A and B directly. Note that method A yields lower values than method B
on animals A in the early stages of lactation, and higher values in the late stages. This
discrepancy is due to: 1) increasing fuel value of the weight gains of the litter with in
creasing age, while in computing results it was assumed that the fuel value per gram gain
is constant; 2) decreasing fuel value per gram milk with increasing milk production, while
in computing results it was assumed that the fuel value per gram milk is constant.
834
19
DMA-B
r
LATIAriON
Fig. 21.12b. See legend for Fig. 21.12a.
Gross efficiency of
milk secretion in
the rat
835
Energy stored in the litter +
(B)
maintenance cost of litter
Calories TDN consumed by mother
The maintenance cost was estimated from the respiratory exchange (heat produc
tion) ; the stored energy, by multiplying the weight gains in grams by 1.5, assuming
that 1 gm. body weight gain is equivalent to 1.5 Calories.
Fig. 21.12a to c present the results on milk production, and energetic efficiency of
l,he rat as obtained by methods (A) and (B) above.
L7
19
A
r-'l
i'ii
L7
u
I 9
r'
n
h
V
h
it
7(
/
^ / V
1
S
1
—
/'
/ i
7/
I5L
DAYS5
lACTATION
Fig. 21.12c. See legend for Fig. 21.12a.
The gross efficiency of milk production in the rat, in the flush of lac
tation, between the 10th and 18th, is seen from Fig. 21.12 to be between
44 and 48 per cent, which is of the same order as in the champion cows.
The milk-production efficiency of the rat is higher than that of the
avevage-supei'ior experiment station cows, perhaps because the rats were
on a relatively better (high-milk cereal) diet than the cattle (grain-hay);
or perhaps because rats—raising large litters in a few days—are lactationally superior to cattle—raising 1 calf during a relatively long period.
The important fact is that the gross energetic efficiency of milk produc
tion in the rat during the flush of lactation is of the same order as in
cows or goats.
21.6.4: Influence of body size on gross efficiency of milk production. It
is said that large animals are better milk producers than small ones because,
836
as a rule, they produce more milk"®. It is also said that small animals are
better millr producers than large because (other conditions being equal) small
n.nimfl.lfi produce more rnillf per unit body weight than large.
Thus, as ex
plained above, the average milk Calories produced per kg body weight are
about 175 for rats and 25 for dairy cows.
However, the comparison of milk production in the preceding section shows
that the energetic efficiency of milk production (the ratio of milk energy proLB^H.
•5000
STYTSCR ERRTQ5J
:
IIOOC
YR C.OS
FO -fiW
•266^^
.IS5 600
700
eoo
900
1200
BODY WEIGHT
Fig. 21.13. Milk (FCM) production as function of body weight of 2-year old, 3-year
old . . . Jersey cattle. Data compiled and averaged from the Jersey Register of Merit
yearbooks 1918, 1920, and classified by ages as follows: 849 records, age 23-25 months
(2yrs.); 338records, age 35-7mos. (3yrs.); 304records, age 47-47mos. (4yrs.); 246records
ages 59-^1 mos. (5 yrs.); 681 records 6-8 yrs.; 449 records 6-8 yrs., re-entries; 191 records
8-10 yrs., re-entries.
duced to food energy consumed, or "dairy merit") is virtually the same in rats,
goats, humans, and cattle. We thus conclude that differences of opinion con
cerning the influence of body size on milk production are due to differences
Cf. McDowell, J. C., U. S. Dept. Agr. Cir. 114, 1930. According to dairy-cattle
herd-improvement association data, there is an increase in yearly yield of approxi
mately 10lb butterfat or 250lbs FCM per 100lbs increase in live weight. Under officialtest conditions, there is an increase of about 20 lbs butterfat or 500 lbs FCM for each
100-lb increase in body weight.
837
in the reference bases employed (Ch. 13). The fact is that when other con
ditions are equal, a large animal produces more milk per animal than a small
animal; a small animal produces more milk per unit weight than a large animal;
large and small animals produce the same amounts of milk energy per unit
food energy. This problem of influence of body size on milk production, with
special reference to practical (monetary) implications, is discussed in the
following chapter (Sects. 22.2, 22.3, and Table 22.1).
BODY
WEIGHT
r—
-
A
*
A
-
^
e
0
(A A .
A«
.
0
<\
e
0
A
U
A
A
A
O
z
o ^
A|
K 4
• ®
1
A
O
A
E
o
' A
A
o
•
33
•ft
-
o
•
«
D
A
•
i
Irner
1
1
1
h
1'
GuerNSEY
20
O
40
V—'
I-
o
o
O 0
5X5 Z
r
A
u
A • "o
*
o8o
7
O
:
A
»
A.
*
O
^
o«
-*•6
A
10
mtco
6cx>
lOOO
BODY
1400
WEIGHT
Figs. 21.14a. Milk (FCM) production on lower curves and gross efficiency, of milk
production on upper curves. Fig. 14a represents the 243 experiment station cows listed
in the table at the end of this chapter; the other curves are also plotted from the same
t^le, as indicated. While FCM production usually rises with increasing body weight,
efficiency usually declines. Further details are given in Univ. Missouri Res. Bulls.,
222, 238, 239.
Small dairy cows are frequently more efficient energetically than large ones (Fig.
21.13 and 14). This is not due to body size as such but because the basis for selection
has been the production percow. To stay in the herd the small cow has had to pro
duce nearly as much as the big one; but if the small cow produces as much as the big
cow, she is more efficient because she has a smaller body and maintenance and there
fore expends less of her feed for maintenance.
Figs. 21.13 and 21.14 also show how milk production tends to rise with body weight
in cattle. This problem is discussed in Chapters 13 and 22.
It thus appears from the above analysis of lactation data of cattle, goats,
rats, and humans that body size as such does not influence the energetic effi-
838
body
weight
T
, [0 :%
40
-
•
•
" Eff."*
y
0
0
0
0
0
0
s
—
0
0
0
cn 30
0
0
0
0
Vi
—
0
%AS
/I
70
:
0
ILL. T. P. DAT/
I
•
PA. DATA
:<
p
30
0
0
0
0
0
0
0
0
0
E-iS
r
®
i
25
3
0
»o°
0
0
<5-
I-Hdi,st.ein^
0°^
) °
10"'^
0—
—
0
»
KXX)
floo
body
weight
Fig. 21.14h. Soc loKond for Fig. 21.14a.
KG VO
BODY WEIGHT
500
400
600
Q
= A
Shorthorn
HOISTEIN
—*
Brown Swiss
1000
1200
BODY WEIGHT
Fig. 21.14c. See legend for Fig. 21.14a.
839
ciency of milk production; other conditions being equal, small and large
animals conveVt the same percentage of food energy into milk energy.
The gross efficiency of milk production of good dairy cattle with respect to
TDNenergy consumed^®® is of the order of 30 percent. However, it appears
from indirect evidence that at the biologic limit, that is, in the highest-pro
ducing champions, the gross efficiency may rise to 50 per cent. Following the
psychologist's I.Q. (intelligence quotient) concept we may say that if the
gross efficiency of milk production of the "average good" cow is 30 percent,
and if a given champion cow's gross efficiency is 50 per cent, the L.Q. (lacta
tion quotient) of the champion cow is 48/30 = 160. A cow having a L.Q.
of 166 is a "lactational genius", just as a man having an I.Q. of 166 is an
"intellectual genius".
21.6.5: Net eflSciency of milk production. Having found that the average
gross efficiency (including maintenance cost) of milk production of good dairy
cattle is of the order of 30 per cent and of champion cows, at the biologic limit
near 50 per cent, we next proceed to investigate the net energetic efficiency
(excluding maintenance cost) of milk production.
It is true that from the
economic viewpoint the overall or gross efficiency is the more important; but
we shall see that the net efficiency is also of considerable interest.
It was previously noted that the net efficiency of milk production with re
spect to TDN consumption is of the order of 60 per cent. The following dis
cussion indicates how this value was obtained.
To evaluate the net efficiency, it is necessary to determine how much of the con
sumed TDN is used for (1) producingmilk, (2) maintaining the animal, (3) gaining (or
losing) body weight.
The partition of the feed for its various uses is evidently a problem of great diffi
culty. This cannot be done by a direct experimental approach. Accordingly, we
devised an indirect statistical approach as follows"®.
Assume that the TDN is used for only the three purposes: producing milk, main
taining the cow, and gaining weight; and write this statement in the form of an equa
tion:
TDN = B{FCM) + C(W''<'") + Da{W)
(21.4)
in which 2'DN = total digestible nutrients consumed; FCM = 4 per cent milk produced;
—jjve weight raised to the 0.73 power; AW = gain or loss in body weight. When
other variables are held constant, B and D represent, respectively, units of TDN re
quired to produce unit of 4 per cent milk, FCM, and to gain unit live weight, AW. The
TDN cost of maintenance is C times body weight raised to the 0.73 power.
Then fit the equation to the data by the method of least squares, that is, by mini
mizing the squares of the residuals with respect to the three constants, B, C, D. This
we did to the yearly lactation records of the 243 experiment station (Table 21.5) Holstein and Jersey (and a fewGuernsey) cows 5 years of age or over (to eliminate age comThe gross efficiency would be less if related to the gross instead of digestible
energy consumed. Thus E. B. Forbes and A. Le Roy Voris, [/. Nut., 6, 395 (1932) ] ob
served a gross efficiency of milk production of 18-23% when related to the gross energy
of the ration.
840
BIOENEltGETICS AND GliOWTH
plications). The energies expended fo/converting milk precursors into milk and for
the process of secretion are lumped with the FCM term. Solving in terms of pounds
per day we obtain
TDN = 0.305FC3/ + 0.053 IF® " + 2.1 ATT
(21.4a)
The meaning of the constants is as follows: if maintenance and weight-gain costs are
held constant, 0.305 lb TDN is used per pound FCM produced; if milk yield and mainte
nance costs are held constant, 2.1 lbs TDN are used for 1 lb gain in live weight; if milk
yield and weight gain costs are held constant, the TDN cost of maintenance is 0.053
time weight raised to the 0.73 power.
Note that equation (21.4) is based on the following unproved assumptions: TDN
for FCM varies linearly with FCM production^"; TDN for weight gain varies linearly
with weight gain; TDN for maintenance is a power function, the power being 0.73,
of body weight (so assumed because basal metabolism of mature animals of different
species varies with the 0.73 power of body weight as explained in Ch. 13); TDN con
sumed is the algebraic sum of the above three terms—and no others.
The last assumption, that TDN consumption was not affected by factors other than
FCM, W, and AW, may be tested by adding another constant, A, to take up the other
unknown influencing factors, as indicated by the equation
TDN = A + B{FCM) +
+ Z)A(iy)
(21.5)
Solving, we obtained
TDN = 0.478 + 0.303 (FCM) + 0.051 TF"'" + 2.18Al'F
(21.5a)
Inspection of eq. (21.5a) shows that the value of A, that is, 0.478 lb TDN, is small in
comparison to the total TDN consumed by a lactating cow (av. for the 243 cows, 17.6
lbs TDN)-, moreover, the values of B, C, and D are inappreciably affected by omitting
A (from0.305 to 0.303 for from0.053 to 0.051 for C; from 2.1 to 2.18 for D). Further
more, the values of the statistical constants are very satisfactory for eq. (21.4).
From equation (21.4a) it is clear that if the overhead maintenance cost is not in
cluded, 0.305 lb TDN, or 553 Cal (0.305 X 1814 = 553), are on the average used to pro
duce 1 lb, or 340 Cal, FCM. The ratio of 340, the Cal in 1 lb FCM, to 553, the Cal in
the TDN required Lo produce 1 lb FCM, that is, 0.61 or 61 per cent, is the net efficiency
of milk production; it is the efficiency of converting TDN into milk, apart from the
maintenance cost.
Gainesi", employing a different approach, found that B = 0.305, exactly the same
value as found by us. For maintenance, however, he found the second term of our
equation (21.4a) to be not 0.05 IV-''', as we found, but 0.129 W-®® "which two equations
give the same results . . . when W = 937, and do not differ by more than 8 per cent at
other values of W from 600 to 1800 lbs."
"Furthermore, there is little choice between
n = 0.60 and n = 0.73; while n = 0.73 is distinctly indicated in preference to n = 1.00.
The lumped data, therefore, support the validity of Brody and Procter's working ex
ponent 0.73 in preference to Ilaecker's exponent 1.00, or Morrison's exponent 0.87.
In the original report (Univ. Mo. Agr. Exp. Sta. Res. Bull. 238, pp. 47-9) an at
tempt was made to evaluate the exponent n in llie equation
TDN" = BiFCM)''
in which TDN" is total TDN consumed, less TDN used for maintenance (C^F-") and
for weight gain (DAlF). The numerical value of n ranged from 1.5 for low-producing
groups of cows to 0.34 for high-producing groups of cows. The interested reader is
referred to this bulletin, and more especially to Gaines, W. L,, J. Dairy Sci., 20, 583
(1937).
1" Gaines, W. L., J. Dairy Sci., 20, 583 (1937), and 21, 645 (1938).
841
When we examine the similar data for various subgroups, great confusion develops.''
This confusion led Gaines to an examination of the maintenance feeding standards
shown ill Fig. 15.3, to suggest that "perhaps some factor not closely associated with
live weight plays a prominent part" and to decide that for the present both, FCM
production and maintenance TDN consumption, should be related to simple body
weight, W, rather than to a fractional power, n, of body weight. He suggested using
the Haecker milk-production feeding standard modified to TDN = O.ZFCM + 0.008 W,
in which FCM is 4 per cent milk and W live weight, all in pounds, as contrasted to the
present author's feeding standard TDN = O.SOSP'Cilf + 0.053 PT ". There is obviously
no appreciable difference between the two for average-sized cows (about 1000 lbs).
The differences concern only extremely small and extremely large cows and only as
they relate to maintenance, not to milk production.
The values in equation (21.4a) may be used for computing the net efficiency of milk
production.
The net efficiency term may be isolated from the gross-efficiency equation,
340 X FCM
Gross-efficeney = ,3,,
^
(lbs)
(2Ua),
by remembering that the denominator includes: (1) TDN expense of maintenance,
represented in eq. (21.4a) by 0.053
and (2) weight gain, represented in eq. (21.4a)
by 2.1ATr. On substituting (1) and (2) from eq. (21.4a), we obtain:
Gross GmClGnCV =
ZmFCM
—
1814 (0.305FCJIf 4- 0.053W^»" + 2.1A1F)
340FCiIf
553^0^'-}- 96.W" + 3700AF
Dividing the numerator and denominator by 553 (the TDN caloriesrequired to pro
duce 1 lb FCM) presents net efficiency, 0.61, as a separate term in the gross efficiency
equation
Gross efficiency - 0.61
^
^^
which is similar to Gaines' "coefficient of efficiency","'
FCM
C. E. = 52.6
FCM -t- SAIW
The net-efficiency equation
Net efficiency
of milk production
milk calories produced
TDN calories consumed less maintenance
may also be written by substituting the values of eq. (21.4a) into it, as follows:
Net efficiency
ZiQFCM
1814 [TDN -
(0.053PF0-" -|- 2.1AW)]
The 61 per cent net-efficiency level is, of course, only a statistical average, for the
given conditions, computed by the given method, and not applicable to an individual
cow.
The detailed method of solving the partition equation (21.4)is shown in the appendix
to this chapter. The numerical data for the individual cows are also listed in the ap
pendix (Table 21.7).
Gaines, W. L., Science, 67, 353 (1928).
842
lilOENEHGETICS AND GHOWTH
Sumnmriziiig, this section presents a sliilistical method for parlitioniiiti the TDN
consumed between msiintciiance, milk prochiclioii and l)ody weight gain, and computing
therefrom net efficiency of milk production with respect to
consumption. It must
be emphasized that the numerical value of the net efficiency would be much loss if it
were computed with respcct to the gross energy of the feed; and much higher if it were
computed with respect to metabolizable energy, and still higher—perhaps 9() or 95 per
cent as found by Graham (previously discussed)—if it were computed with respect to
net energy or to the milk-precursor energy entering the mammary gland.
It is evident that the (jross energetic efficiency of milk secretion, which
cariies the burden of the maintenance cost of the cow, can never be as great
as the net efficiene.y, which is not thus bui-dened with maintenance taxes. As
production increases, the maintenance tax per unit milk produced becomes
less and less; therefore, the gross efficiency approaches nearer and nearer to
the net efficiency level, but at decreasing iiicrements, in accordance with the
law of diminishing returns. The relation between gross efficiency and milk
production (FCM) level is shown in Fig. 1.2 (Ch. 1). Since the net effi
ciency of milk production is of the order of 60 per cent, the gross efficiency
can never reach 60 per cent, but it may approach 50 per cent. This checks
with the estimated gross efficiency for the 700-11) Jersey champion cow Stonehurst Patrician's Lily, previously cited.
21.7: Summary. This chapter discusses the following problems.
(1) The daily industry and its place in the national, especially agricultural,
economy. Dairy husbandry is the largest branch of agriculture from the
viewpoint of return to the farmer and numl)er of persons employed.
(2) The unique compo.sition of milk, most conspicuously its lactose, casein,
short-chain fatty acids, minei-als, especially (calcium and vitamins. The
composition of milk is loosely related to the ppr(!entage growth rate or matura
tion rate of the body.
(3) The unique composition of milk is associated witli itii unique nutritional
properties. Milk was evolved especially for the nutrition of young mammals
and has a matchless combination of protein of high biologic value, of ealchun,
phosphorus and vitamins. It is poor, however, in iron, copper, manganese,
and apparently magnesium. Milk happens to supplement almost perfectly
whole-cereal diets for adult humans.
Almost -J- of the dietary energy con
sumed in this country in "adequate" and "liberal" diets comes from milk.
The skimmilk-butter-margarine problem is discu.ssed in some detail.
(4) From the viewpoint of i-elative energetic economy of meat, egg, and
milk production, the gross efficiency of early growth and of average milk pro
duction is of the same order.
As, however, the animal increases in size,
its efficiency for meat production decreases rapidly because of the mounting
maintenance cost in comparison to the growHh increments. Moreover, much
of the animal body is inedible, whereas all of milk is edible. Furthermore,
with the exception of some visceral organs, as liver and kidney, milk has unique
supplementary properties not found in meat. Finally, the possibility of in-
MILK: NUTRITIONAL, SOCIAL, PHYSIOWGICAL ASPECTS
843
creasing the energetic efficiency of milk production (by improved breeding
methods) is greater than for meat prcduction. In general, the gross mergetic
efficiency of milk production tends to be about twice that of egg production
and about five-fold that of meat production (Ch. 3).
(5) Physico-chemical considerations of milk production indicate complex
interdependence between osmotic and enzymatic factors and between.the
protem, fat, lactose, and water constituents. Milk sugar, is produced not
only fiom blood sugar, butalso from blood lactic acid and from amino acids.'
Milk fat is derived mostly from blood fat, and milk protein from blood pro
tein and amino acids.
(6) It is shown that there is a considerable heat increment of lactation.
It is not possible to measure the hasal metabolism of lactation because the
post-absorptive condition requisite for basal metabolism depresses the milk
flow so that lactation is no longer normal.
(7) It is shown that good experiment-station dairy cattle (for example,
1100-lb cows producing about 35 lbs FCM per day and consuming 21 lb TDN
per day) produce milk at a gross energetic efficiency near 33 per cent with
respect to TDN consumed, thatis, about one-third of the TDN fed a good
cow is recovered in the milk. By proper breeding, the gross efficiency may
be increased to a maximum near 50 per cent. The net efficiency of milk pro
duction (hot counting the mamtenance cost) with respect to TDN consump
tion is shown to be of the order of 60 per cent.
(8) The gross energetic efficiency of milk production is apparently inde
pendent of live weight as such. It is true that the ratio of milk-energy yield
to body weight is greater in small animals, such as 120-lb goats, than in large
animals such as 1200-lb cows; but the ratio maintenance-energy cost to body
weight is likewise greater for the 120-lb goat than for the 1200-lb cow, with
the net result that the extra maintenance cost counterbalances the extra milk
yield and the gross efficiency is unaffected by body size.
(9) The appendix indicates the method for fitting the "partition equation,'"
partitioning the food consumption between maintenance, milk production,
and body gain; and presents numerical data on milk production, feed con
sumption, body weight, and related items.
Appendix: Estimating the amounts of consumed TDN used for FCM production,
maintenance, and weignt gain (solution of eq. (21.4a)). The partition of the con
sumed TDN between its uses for each, FCM, maintenance (Pf "), and weight gain
(AW^), may be carried out graphically, or algebraically by the method of least squares.
The graphic method consists in plotting TDN successively against eachof the inde
pendent variables, namely FCM, 1^ ", and APT; correcting observed TDN values for
the influence of one variable by approximating TDN cost per unit of that variable;
subtracting computed TDN required for the one variable from the observed TDN for
each datum; correlating corrected TDN with another variable and determining a sec
ond correction. These first approximations of the parameters are improved by succes
sively repeating this process of approximation until the sum of the squares of the
differences between observed and computed TDN is minimum.
844
The least-squares method eliminates the laborious successive approximations. The
solution of the partition equation
TDN = BiFCM) +
+ DAW
(21.4)
by the least-squares method involves substituting in three "normal equations" simul
taneously, and weighting the trendsof TDNwithFCM, W, and AW so as to give at once
a minimiim value for the sum of the squares of the differences.
An obvious objection to equation (21.4) is that it was formulated on the assumption
that the milk secretion, maintenance, and weight-gain factors are independent. This
is by no means certain. Moreover, since the coefficients in the equation are computed
by the method ofleast squares, it is clear that if the value ofone coefficient is toohigh
due to some experimental or biological situation, the values of the other coefficients
will be influenced thereby. Each of the terms represented in equation (21.4) has its
separate set of experimental errors and biolo^cal variations. When combined into
one interrelated system, each of these terms influences the value of every other term.
There consequently results a very complex system of interinfluencing relationship.
A large population compensates and smoothes out individual experimental errors
and biological variations so that dependable average values for the equation constants
B, C,andD result. But if a small population is combined with large errors and varia
tions, the equation constants are no longer dependable, and are often absurd, as il
lustrated by the following numerical examples.
The aforementioned three "normal equations" for equation (21.4) are:
XiTDNWCM) = B^{FCMY -1- CS(F(7ilf)(lF<>-") -1- D^{FCM){AW)
S(rZ)i\r)(W^9-») = i5S(FCM)(Tf''-") + 02(17° •")« + DS(T^^<>-")(ATf)
s(rz)j\r)(AiF) = b^[fcm)(,aW) + C2(PF« ")(ATr) -i- d^{awy
Taking, by way of illustration, the data for the 15 World's Fair Holsteins listed in
Table 21.6, we obtain the following summations:
tiTDN) (FCM) = 19526.1508
SlTDN) IFo-w) = 74486.866
i ™
aV) =
S(FCM) (A IV) =
593.90890
SOK'-")*
= 622017.86
3W.95468
36129.7161
S(A
S(FCM) (IFo.n) = 136482.688
(A IF) = 23M-OT17
=
XlTDN)*
11.251476
= 10642.4553
Substituting in the "normal equations" we have:
1952.1508 = B 36129.7151 + C 136482.688 + D 593.90690
74486.866 = B 136482.688 + C 522017.86 + D 2303.8917
327.95458 =» B
593.90690 + C
2303.8917 + D
.
11.251476
Solving these equations we obtain B —0.11642, C = 0.11146, and D —0.18040, i.e.,
TDN = 0.116 FCM 4- O.llTF® " + O.ISOATT. Illustrating the solution by Doolittle's
method^®' we have:
Lme Reciprocals
I
II
III
1
2
-.0000276780483
3
4
6
6
-0.000155174587
7
8
9
10
11
B
36129.7151
i.uoou.oo
-1.08307862
30129.7151
-1.00000000
c
136482.688
622017.86
D
593.90690
2303.8917
11.251476
—
-19526.1508
-74486.866
-327.95458
Sum
153681.15920
586317.6737
2581.095496
153581.15920
-19525.1508
593.90690
136482.688
-4.253594542
.5404018067
-.016438184
-3.77757443
686317.5737
-74486.866
2303.8917
522017.86
-680542.0166
73767.710
-2243.5275
-515573.51
6775.5571
-729.156
60.3642
444.35
.113146554 - -S96220265
-.009366906
-l.OOOOOOO
2581.095496
-327.95458
11.251476
-2526.239169
320.95802
-9.762751
-54.099620
6.83000
-.565431
.756707
-.16656
.923294
-.819573
.180397576
-1.0000000
^ ,180397576
C =
.111456771
B = .116416411
See Ezekiel, M., "Method of correlation analysis," New York, 1930, Ch. 12. See
also.Mills, F. C., "Statistical methods applied to economics and business," New York,
1924, p. 577.
845
The standard error of estimate for equation (21.4a) is
{TDN)^ - BCTPmiPCM) - C-L{TDN)(W'>'") - DMTDN)W)
-s!
N
where N is the "degree of freedom." The "degrees of freedom" is the number of data
points less the number of arbitrary constants in the equation fitted; thus N =
15 -
3 =
12.
Substituting:
10642.4553 - (.11642 X 19525.1508) - (.11146 X 74486.866) - (,18040 X 327.95458)
12
'
10642.4553 - 2273.1181 - 8302.3061 - 59.1630
12
7.8681
12
= 0.655675
St = 0.810
The standard error of estimate, Sr = 0.81, means that two-thirds of the time the
TDN computed from this equation will agree with the observed TDN consumption
within db 0.81 lb.
This small value of Sr leads one to think that the numerical values of B, C, and D
are significant and reliable. As a matter of fact these values are so far out of line that
they must be considered meaningless. Thus the maintenance of a 1000-lb cow is, ac
cording to this equation, 0.1115 X 1000 " = 17 lbs, which is over twice the Morrison
allowance of 7.9 lbs, and therefore absurd. The net efficiency is, according to this
equation, .1164
,^1? ^X 1814 = 164 per cent, which is of course impossible. In other words,
of the available TDN, far too much is apportioned by this equation to maintenance,
and far too little for milk production (and for weight gain).
Does this mean that equation (21.4) is wrong? Not necessarily. It means that the
number of animals in the population is too small in comparison to the variability. The
data points are too irregular and too few to give the equation a lead, so to speak, to
the real situation. The three sets of guide posts involved in showing the road {TDN
trends for FCM production, maintenance, weight gain) are so few, and distributed so
erratically, that they are blurred and therefore useless as guides for reaching the de~
sired goal.
It is not the fewness of the data that is alone responsible for the erratic results, as
the combination of fewness, limited range, and erratic distribution of data. The er
ratic distribution of the data is probably due to their experimental errors. Better
(even if fewer) data give better results. Thus equation (21.4) fitted to only 10 of the
Pennsylvania Animal Nutrition Institute (Forbes) data gave entirely satisfactory
results. In this case the value of C for equation (21.4) was found to be 0.053, so that the
maintenance for a 1000-lb cow is 8.2 lbs (which is the average of the value found for
the 243 Experiment Station cows (Fig. 21.14a); the value of B was found to be 0.292, in
dicating net efficiency of 64 per cent (in comparison to 61 per cent found for the 243
experiment Station cows). This brings us back to the statement that reliability of the
equation parameters is conditioned on accuracy of the data. To summarize, equation
21.4 gives dependable average values separately, for FCM production, maintenance,
weight-gain but only provided that the population is reasonably large and the data
are reliable.
\
846
Table 21.1. Comparison of the National Reskarch Council (1943) N utritionalNbed Standard for a 70-Kg Moderately Active Man with the
Nutrients Supplied by One Quart of Raw Milk.
Average daily
requirement for a
70-Kg, (154.1b)
Nutrients
Approximate
Amount in one
quart milk
adult
Protein (gm)
Calcium (gm)
Phosphorus (gm)
Iron (mg)
Vitamin A" (I.U.)
12
50C0
400
75
1.8
18
2.7
Vitamin D" (I.U.)
Ascorbic acid" (mg)
Thiamine (mg)
Nicotinic acid (mg)
Riboflavin (mg)
requirement sup
plied by one
quart raw milk
34
675
1.16
0.91
1.94
1900
25
19.4
0.28
70
3000
0.8
1.3
Calories
portion of the daily
h
\
li
1
i,
1
•h
1
•h
I
1.1
1.7
The Calories in milk are divided equally between fat and non-fat fractions:
Constituent
Grams/quart
Calories/quart
Fat
37
333
Lactose
Protein
49
34
1361
Table 21.2
1961
332
Fatty Acid Composition op Fat in Milk and Beef Plasma.
Percentage by weight in:
Saturated acids
Carbons
beef plasma
milk
Butyric
Caproic
Caprylic
Capric
Laurie
Myristic
Pdmitic
Stearic
Arachidic
4
6
8
10
12
14
16
18
20
3.7
2.0
1.0
2.6
1.7
8.3
25.4
10.7
0.4
10
14
16
18
18
0.2
1.2
5.0
32.4
4.0
0.4
0.4
24.5
12.3
0.8
Unsaturated acids
Deconoic
Tetradecenoic
Hexadecenoic
Oleic
Octadecenoic
C 20 to 22 unsat.
Linoleic
Linolenic
20-22
2.5 (Palmitoleic)
17.4
1.3 (Arachidenic)
36.5
4.2
/
Table 21.3
Composition op Milk op Dipperent Species and Growth Rate,
(After Abderhalden, modified, enlarged with averaged data from various sources
and percentage-distribution sections added.)
Caloric values
milk solids
rate (days
for dou
Species.
uents as per
centages of
percentages of
of whole milk
Grow til
of constit
Constituents as
Constituents as percentages
caloric values
of milk
blingbody
Fuel
value
Cal/
gm
weight)
Fat
Cow
70 (47)
Goat
Man
22
180
60
Horse
Ass
Camel
Sheep
35 (15)
Reindeer
14
0
Dog
Cat
Rabbit
Rat
6
6
7
Guinea pig
Elephant
4.4
4.1
3.8
1.6
1.5
5.4
6.2
22.5
7
8.5
5
IG
15
7
15
3.8
3.7
1.6
2.7
2.1
3.0
5.4
10.3
6
7.5
7
14
12
5
4.9
Protein
Whale
44 (22)
Porpoise
Dolphin
Monkey
49
15
3.9
12
20
Water buffalo
Australian antcater
Pigeon crop "milk"
2
8
7 (12)
11
10
2.1
6
11
13
4.9
4.2
7.0
6.1
6.4
3.3
4.3
2.5
4
3.7
5
2
Lactose
3
2
3.4
1.8
0.7
0.8
0.2
0.5
0.3
0.7
0.9
1.4
0.9
Ash
1.2
0.6
2.2
2.0
0.8
0.5
1.3 0.6
6
6
0.3
4
0.9
3
0.8
0
1.5
86.2 13.8 32
12.9 32
12.6 30
11.0 15
10.3 15
12.4 44
17.1 37
63.3 36.7 61
83
17
39
79
21
41
82
18
28
47
65
35
70
47
30
85
15
50
62
73
27
40
83
51
38
62
79
70 30
48
87.7 12.3 32
77.1 22.9 52
57
63
37
77
23
36
87.1
87.4
89.0
89.7
87.6
82.9
Water
Totalsolids
27
29
13
25
20
24
32
28
34
36
40
41
38
36
20
13
18
32
17
26
32
58
36
33
56
56
62
27
26
7
22
18
28
6
9
13
14
3
2
jFat Protein
5.1
6.2
1.6
4.6
2.9
5.6
5.4
3.8
5.0
5.7
3.4
6.4
6.2
3.3
0.9
1.0
19
Lactose
49
18
9
0
2.4
3.9
2.3
6.7
Ash
53
54
50
29
28
66
59
80
64
63
48
69
69
69
80
92
90
68
76
73
76
42
20
22
9
22
18
16
23
16
24
25
30
27
25
22
12
6
9
20
18
16
19
58
26
24
41
49
54
18
18
4
12
12
22
4
6
9
8
2
1
12
5
11
5
0
.75*
.75*
.68
.98
2.4
• The combustion value of goat's milk containing 4% fat is the same as for cow's milk containins
4% fat, namely, about 340 Cal/lb, or 0.75 Cal/gm.
Fat
Protein
Table 21.4. Time Changes in Composition op Colostrum Milk after the
First Parturition, Average op Two Cows.^®
Lactose
% of first milking
Time after
calving
Total
solids
Protein
Fat
Lactose
Ash
Ca
Mg
K
Na
P
Cl
100
91
68
52
62
48
100
72
41
29
100
103
107
117
119
118
100
84
72
66
70
100
76
64
100
74
47
36
36
38
100
107
104
26
100
72
80
75
66
70
83
70
54
100
70
62
63
62
66
60
59
22
100
98
92
52
52
50
100
122
112
70
60
54
69
68
60
(hrs)
0
6
12
24
36-40
44r48
60-6
68-72
10-11 days
28
27
26
22
114
110
138
69
66
67
60
60
64
62
65
62
54
118
40
38
126
120
117
31
Each as percentage of all minerals
Time after
114
128
91
81
82
83
83
56
Each as percentage of total solids
calving
\
Ca
Mg
28
26
24
23
24
24
24
24
26
4
3
2
2
2
2
2
2
2
K
Na
P
Cl
Ash
Protein
Fat
Lactose
16
10
8
10
10
8
9
10
9
8
26
22
15
18
18
18
16
16
17
54
44
32
39
29
30
28
28
23
26
35
39
34
29
28
34
34
31
14
23
22
23
5
4
6
6
6
6
6
6
6
(hrs)
A
0
6
12
24
V
1
36-40
44-48
60-64
68-72
10-11 days
\
22
22
25
28
26
26
26
32
22
20
22
24
847
16
13
17
23
31
35
35
32
32
40
Table 21.5.
Data on the United States Dairy Industry.
Annual per capita consumption of dairy products, lbs
Dairy cattle,
million head
Calves
birth
Cows
1940
1941
to
23.0
26.2
25.0
25.5
Calves
1 to 2
lyr.
yrs.
5.2
5.5
6.0
6.2
4.9
5.0
5.5
5.7
Table 21.6
tion
billion
lbs.
pot,
Butter
bakers,
Ice
Cream
ratra
11.3
14.1
17.5
18.5
products
million
whole
milk
and
8/yr.
cottage)
353
338
347
347
818
797
825
814
103
105
112
118
Evapo- from dairy
(except
Fluid
fresh
milk
to whole
milk
C^ farm
income
Cheese
All dairy
products
equivalent
produc
Year
1930
1936
Annual
milk
17.3
16.5
4.6
5.4
10
10
17.0
16.4
6.0
6.0
12
15
1387
1517
1897
Summary of the Data in Table 21,7 Discussed in Section 21.6.
Speculative (i. e., computed
on the basis of debatable
Factual
assumptions.)
Data
Av.
Live
No.
of
Wt.,
Cows
Lbs.
Com
Av.
Av.
Av.
Daily
Daily
Live
Wt.
FCM
Produc
Gains,
Lbs./
Day
tion,
Lbs./
Day
puted
con
sump
Gross
(from
tion.
Lbs./
Day
Effic.,
equa
%
tion),
%
B
C
D
Sr
Net
CMO'» + D ^
Effic.
Experiment Sta. (Res.
Bull. 222)
La.-Purchase
Constants of Equation
TDN = B(FCM) +
Av.
Ob
served
Daily
TDN
243
1087
0.117
28.26
17.64
30.1
62.2
0.305
0.053
2.13
1.02
73
5
15
25
28
45
65
34
1161
1208
1290
948
1252
1104
1158
1280
0.773
0.675
0.823
0.599
0.920
0.682
0.736
0.859
40.97
41.49
48.81
45.59
32.56
46.21
41.93
35.69
23.90
27.78
26.63
25.09
20.69
25.90
24.16
22.60
31.8
28.0
34.3
33.6
29.6
33.2
32.3
29.6
51.5
42.8»
53.6»
48.7*
64.3*
49.7*
53.2*
51.9*
0.367
0.274
0.116
0.217
0.205
0.263
0.373
0.347
0.046
0.087
0.111
0.098
0.066
0.083
0.047
0.050
1.19
-0.319
0.180
0.772
2.08
-0.276
0.510
1.15
1.44
42
10
1322
1131
1130
0.058
0.215
0.243
51.15
36.20
33.64
27.83
34.3
34.4
31.0
82.4
64.5
53.6
0.229
0.292
0.350
0.084
0.053
0.046
0.338
1.52
1.88
1.84
0.76
1.43
Exposi
tion:
All breeds
Brown Swiss
Holstein
Jersey
Shorthorns
Class A
Class B
Class C
111. Testing Plant
Holsteins
Forbes' Pa. Holsteins...
All of above
368
19.75
19.96
Milk (FCM) Production and Ratios
Absolute FCM
Data
Live
Observed
Absolute TDN
Ratios of FCM Calories
Production/
day
produced to:
Consumption
Com
No.
of
Weight,
Cows
Pounds
243
1087
28.26
9608
1.48
0.30
0.61
0.61
17.64
32000
73
5
15
25
28
1161
1208
1290
948
1252
1104
1158
1280
40.97
41.49
48.81
45.59
32.56
46.21
41.93
35.69
13930
14107
16595
15501
11070
15711
14256
12135
2.05
1.87
2.25
2.64
1.54
2.40
2.10
1.66
0.32
0.28
0.34
0.34
0.29
0.33
0.32
0.30
0.52
0.43
0.54
0.49
0.54
0.50
0.53
0.52
0.97
0.88
1.07
1.24
0.92
1.13
0.99
23.90
27.78
26.63
25.09
20.69
25.90
24.16
22.60
43355
50393
48307
45513
37532
46983
43826
41000
51.15
17391
12308
11438
2.32
1.84
1.71
0.34
0.35
0.32
0.60
0.75
0.80
27.83
19.75
19.96
50483
35736
36207
C3
C4
C5
0.82
0.64
0.54
C6
C7
C8
C9
Ob
puted
Com
served
TDN
puted
Total
Cals. for Mainte Pounds Calories
Con
FCM
nance,
sumed
olism,
Prod. Calories
Calories TDN
Com
puted
Basal
Pounds Calories Metab
Only
Experiment Station
Exposition
All Breeds
Brown Swiss
Holsteina
Jerseys
Shorthorns
Class A
Class B
Class C
Illinois Testing
45
65
34
Plant
Holsteins
Forbes' Pa. Holsteins...
Ave. of all groups
42
10
368
Column number
1322
1131
1130
C1
36.20
33.64
C2
Footnotes: Column 2, observed; C.3 = C.2 X (340); C.4 —
9=8X(1814);10 =^;11 =
in Col.* 1** 16= 15X (1814); 17a
C.3
;C.5
C.3
"cHo
0.78
3
3
7 = -jg;
8 =, observed;
=|;13 =22 X2; 14 •= 13 X(1814); 15 =23 XM"" values ofweight M, given
ig =
80
19s computed from. Basal metabolism (Cal) = 39.5Mo-n where li
16
14
islive weight in pounds given in Col. 1;20 = yg; 21 = •jj.
848
Table 21.6.
Continued
Computed Basal
Feed (TDN) Consumption, and Ratios
Ratio of TDN
Calories Con
Com
Basal
Met..
Calo
rics
Experiment
Milk
Com
Production
puted Ob
Main served
Mainte
TDN, Cals.
Cals./
day
ries
I"
Sta
tion
All Breeds
Brown Swiss
Holsteins
Jerseys
Shorthorns
Class A
Class B
Class C
4.9
2.0
3.3
6.4
6.7
6.6
7.7
5.2
7.2
6.5
5.6
3.0
3.1
3.6
2.9
2.9
3.4
3.0
3.1
3.2
3.1
3.7
2.5
3.4
15637
8.7
15836 48.9
49.5
6475
2.4
2.4
0.305 0.053
15.0
15.2
17.9
16.7
12.0
17.0
15.4
13.1
27264
27627
32489
30348
21677
30765
27917
23763
7.9
8.8
33.2
31.6
32.3
27.3
4.0
3.7
4.4
0.367 0.046
40.7
29.5
32.8
37.8
6806
7527
7363
5881
7204
6558
6792
7321
2.1
2.1
2.1
2.1
2.1
2.1
2.1
8.5
14403 62.9
15927 54.8
15582 67.3
12444 66.7
15250 57.8
13877 65.5
14385 63.7
15492 58.0
2.1
3.0
4.7
4.1
3.2
28861
42.1
57.2
7484
3.9
2.8
0.229
16326 53.7
14331 59.1
45.6
39.6
018
6691
6687
2.4
2.1
2.9
3.2
C19
C20
C21
0.292 0.053
0.350 0.047
C22
C23
8.6
6.9
8.4
7.7
7.9
3.0
2.7
3.4
6.8
1.8
3.0
11.7
21242
15.9
5.3
5.4
ClO
2.2
2.9
3.2
C12
10.6
11.8
19228
21405
C14
9.0
7.9
Testing
Plant
steins
Equation
Constants
lism,
Exposition
Illinois
Me
tabo
Between
nance
te
FCM,
nance, Calo
Calo
ries
Ratio to
Percentage
Computed
Distribution Com
of Consumed puted Basal Met.
of
Computed
Basal
TDN
Data
puted
Met. and Ratios
Computed
Computed Daily TDN
Consumption for
sumed to
849
5.2
Hol
Forbes' Pa. Hol
steins
Ave, of all groups.
Column number..
2.5
CU
C13
C15
C16
C17
0.084
Table 21.7. Individual Milk, Feed, and Body Weight Rbcobds of Cows
Discussed in This Chapter and the Following Chapter."'
Aver
age
Live
wt.,
lbs.
Feed
Milk
TDN. FCM,
lbs./ lbs./
day
day
Live
Gross
Profit
Energetic
per year,
Effic.
dollars*
wt.
fhl";
IDS./
day
Gross
EiKêtic
Aver
age
Not
Cor
rected
rected
for
for
Live
cor
wt.
gain
wt.
per
cow
gain
per
1000
wt.,
lbs.
Feed
Milk
TDN, FCM,
lbs./ lbs./
day
day
24.0
28.3
29.2
27.2
30.2
36.1
46.5
42.6
37.3
44.9
.550
.617
.417
1.225
.567
28.3
30.8
27.4
25.7
27.8
29.0
81.6
27.8
27.1
28.5
132
184
151
124
162
10.1
10.8
9.7
9.1
9.9
25.8
25.5
26.5
26.5
27.5
26.6
27.0
26.2
26.0
27.6
26.8
27.1
27.0
26.2
27.1
43.7
43.5
48.8
45.8
52.4
50.1
49.5
51.6
45.5
62.4
48.6
55.1
45.7
47.6
41.5
.967
.700
1.392
.750
.567
.842
.725
.717
.975
.450
.967
.767
.308
.992
1.225
31.7
32.0
34.5
33.3
33.1
36.8
32.4
33.5
35.7 36.6
35.3
36.7
34.3
35.4
37.1
38.3
32.8 34.3
42.5
43.3
34.1
35.6
38.1 .39.4
31.8 32.2
34.0 35.6
28.7 30.4
cor
wt.
178
178
211
189
232
220
213
235
190
305
208
254
186
204
155
11.2
11.2
11.8
11.3
12.4
12.0
11.8
12.4
11.4
13.4
11.8
12.6
11.2
11.7
10.2
Cor
rected
for
wt.
per
per
1000
cow
lbs.
FCM
176
189
11.5
gain
Jerseys, 25
782
786
902
914
914
927
Holsteins, 15
1167
1225
1236
1239
1247
1252
1264
1283
1286
1292
1327
1343
1344
1398
1438
Not
rected
for
gain
Brown Swiss, 6
1181
1248
1367
1384
1467
wt.
fbt/
day
lbs.
FCM
'Louisiana Purchase World's Fair" Data
Profit
per year,
dollars*
Live
928
930
936
961
974
976
984
990
1002
1036
1036
1046
23.8
22.6
23.9
25.1
24.1
26.1
25.5
25.7
26.0
23.0
24.3
23.3
1047
23.3
24.6
24.5
26.5
25.4
25.6
25.8
26.5
27.5
25.3
25.9
1050
1090
27.3
26.0
42.0
42.8
42.3
47.7
43.3
50.8
50.5
42.3
47.5
38.4
39.9
41.3
41.1
46.6
46.2
48.6
47.8
47.4
47.6
50.6
54.2
39.9
45.8
50.6
44.8
.458
.758
.842
.633
.358
.683
.425
.733
.292
.483
.658
.425
.558
.742
.542
.525
.617
.675
.608
.583
.642
.708
.533
.642
.850
33.0
31.4
33.1
34.2
33.7
36.5
37.2
30.9
34.2
31.3
30.8
33.2
33.0
35.5
35.3
34.4
35.3
34.7
34.6
35.7
37.0
29.6
33.2
36.5
30.8
33.8
37.0
34.6
36.7
34.3
37.6
37.9
32.0
34.6
32.1
31.8
34.0
34.0
36.8
36.3
35.3
36.4
35.8
35.5
36.7
38.0
30.6
34.0
37.6
32.0
178
211
184
228
229
168
204
154
158
174
172
205
203
210
210
206
206
224
245
153
193
227
178
12.1
11.5
12.1
11.7
12.3
12.4
10.9
11.8
11.0
10.9
11.5
11.5
12.1
12.0
11.8
12.0
11.9
11.9
12.1
12.4
10.5
11.5
12.3
10.9
For the detailed sources and analyses of these data, see Univ. Mo. Aer. Exd Sta
Res. Bulls. 222, 1935, 238 and 239, 1936.
®
850
Table 21.7.
Aver
age
Live
wt.,
lbs.
Feed
Milk
TDN, FCM,
lbs./ lbs./
day
day
Gross
Profit
Energetic
per year,
dollars*
Effic.
Live
Not
Cor
rected
rected
for
for
cor
day
wt.
wt.
per
cow
gain
per
1000
10.1
18.9
21.3
22.5
19.6
20.2
20.1
21.7
19.2
20.1
20.6
17.6
22.2
21.4
18.8
19.9
23.4
20.5
20.9
18.7
20.9
23.9
20.8
25.6
22.8
20.6
21.3
33.6
21.1
.775
1.167
38.5
43.4
.625
1.158
32.4
34.8
37.5
35.4
33.5
33,0
24.0
31.4
26.9
32.5
32.6
27.9
33.7
31.6
33.0
32.8
35.4
1.067
1.092
21.1
34.7
29.0
40.6
35.9
30.7
34.8
.725
.942
1.050
1.067
1.525
.992
.100
1.058
.950
.667
.383
.917
1.058
.817
.342
1.950
1.192
.825
.642
.850
.667
1.158
31.7
24.5
38.4
38.2
27.0
33.3
34.9
33.0
28.9
32.3
22.4
28.5
28.6
27.5
28.5
27.8
31.8
25.2
30.2
29.4
35.5
19.0
27.2
26.0
29.7
29.4
27.9
30.6
Profit
per year,
Aver
Live
wt.,
lbs.
Feed
Milk
TON. FCM.
lbs./
day
lbs./
day
dollars*
Live
wt.
gain,
lbs./
day
lbs.
FCM
Not
cor
rected
for
wt.
gain
Cor
rected
for
wt.
per
per
lOOO
cow
lbs.
FCM
gain
Dixon, Illinois, Testing Plant Holsteins,
Shorthorns, 28
19.9
Gross
age
wt.
gain
1014
1003
1094
1100
1146
1172
1184
1186
1198
1206
1214
1214
1223
1226
1230
1286
1289
1297
1306
1314
1326
1329
1380
1386
1398
1405
1408
1442
Continued.
42 cows—Continued
33.2
26.8
39.8
40.9
28.6
35.7
36.4
35.0
30.7
34.6
24.6
30.2
28.8
29.1
30.0
29.0
32.6
26.5
32.2
30.8
36.3
21.4
28.9
27.3
30.6
30.8
29.1
32.8
136
66
178
200
113
147
164
148
126
136
65
116
100
116
120
101
137
102
129
125
156
40
122
97
156
137
111
137
11.1
8.6
12.7
12.7
9.6
11.6
11.9
11.6
10.3
11.3
7.4
10.1
10.1
9.8
10.1
9.9
11.1
8.8
10.7
10.4
12.0
5.1
9.7
9.2
10.6
10.4
9.9
10.8
1464
1469
1514
1531
1538
1566
1609
1660
1683
1748
27.6
30.8
28.6
23.8
29.0
28.7
30.3
28.0
29.4
31.9
46.9
64.6
57.3
36.4
53.0
56.3
50.3
40.0
61.4
58.4
.167
-.110
-.055
.548
.055
.205
.208
.192
.137
.274
31.8
•39.3
37.5
28.7
34.3
36.7
31.1
26.8
39.1
34.3
31.9
39.3
37.5
28.9
34.3
36.8
31.1
26.8
39.2
34.4
191
303
261
136
228
254
201
138
287
251
11.2
12.8
12.5
10.2
11.8
12.4
11.0
9.4
12.8
11.8
Pennsylvania (Forbes) Holsteins, 10
867
1008
1042
1073
1092
1102
1198
1207
1308
1408
16.0
16.6
20.0
18.9
19.8
20.6
21.6
19.1
20.7
24.4
32.5
30.6
39.7
36.1
35.5
34.6
39.4
34.9
33.6
45.1
-.056
.036
.259
.205
-.056
.652
.580
.154
.542
-.165
38.0
34.7
37.3
35.8
33.7
31.5
34.3
34.3
30.5
34.7
37.8
34.7
38.0
36.4
33.5
33.0
35.7
34.6
31.7
34.3
149
132
181
160
151
140
169
150
132
195
12.6
11.8
12.5
12.1
11.6
11.1
11.8
11.8
10.8
11.8
90
134
11.2
Savage's Guernseys, 2
846
1072
16.0
19.3
24.4
32.7
.200
.514
28.5
31.8
29.3
33.8
10.1
Dixon, Illinois, Testing Plant Holsteins,
Savage's Holsteins, 14
42
889
962
976
1086
1126
1161
1194
1198
1210
1211
1220
1221
1229
1233
1245
1247
1265
1271
1272
1291
1297
1312
1330
1331
1340
1347
1350
1354
1358
1360
1425
1448
26.6
25.1
25.9
23.2
26.4
27.7
26.4
29.9
28.6
26.6
30.0
27.3
28.0
29.4
28.1
27.1
28.3
29.0
28.8
26.9
27.3
28.2
28.5
25.8
26.1
27.8
25.5
27.1
29.2
29.5
26.1
30.1
43.6
43.7
38.7
41.3
47.0
52.5
42.7
67.2
67.8
43.0
61.4
41.0
53.5
47.0
50.2
44.7
55.3
55.6
52.5
53.8
50.9
43.9
53.2
45.6
53.4
59.9
41.9
54.2
56.8
56.8
42.6
56.7
.370
.192
-.110
.520
.358
.233
-.356
.096
.110
.000
.000
.559
-.301
-.301
-.068
.206
.274
.247
-.333
-.329
.301
-.274
.000
.315
-1.041
.109
.247
.055
-.192
.041
.137
-.269
30.7
32.6
28.0
33.4
33.3
35.5
30.3
42.1
44.4
30.3
38.4
\ 28.1
35.9
33.2
^3.4
30.9
36.6
36.0
34.2
37.5
35.0
29.2
35.1
33.1
38.4
40.5
30.8
37.5
36.4
36.1
30.5
35.2
30.8
32.7
28.0
33.7
33.5
35.6
30.2
42.2
44.4
30.3
38.4
28.3
35.7
33.3
33.4
31.0
36.7
36.1
34.1
37.3
35.1
29.1
35.1
33.2
37.8
40.5
30.9
37.5
36.4
36.1
30.6
35.1
172
181
141
175
198
231
167
327
338
168
284
10.8
11.3
10.0
11.6
11.5
12.0
10.7
13.3
13.6
10.7
12.7
ISO
10.0
12.1
10.6
11.6
10.9
12.3
237
182
212
178
249
247
226
246
222
166
233
192
247
286
166
248
255
253
168
248
12.2
11.8
12.5
12.0
10.4
12.0
11.5
12.7
13.1
10.8
12.5
12.3
12.2
10.8
12.0
985
990
1035
1053
1054
1073
1090
1150
1175
1179
1184
1239
1253
1341
21.2
21.2
20.9
22.9
20.2
20.8
22.7
21.7
21.4
22.7
24.4
23.8
23.4
22.1
35.8
36.9
29.7
42.5
29.9
30.4
37.7
38.5
32.4
37.5
40.6
40.2
38.2
30.1
.695
.086
.838
.295
.029
.162
.657
.638
.581
.019
.209
.419
.752
.438
31.7
32.6
26.6
34.9
27.8
27.3
31.1
33.3
28.4
30.9
31.2
31.6
34.0
32.9
29.1
35.9
27.9
27.8
33.2
35.5
30.1
31.0
31.8
32.8
30.7
29.4
26.6
25.5
145
153
102
185
108
99
11.1
11.4
9.4
11.9
9.9
9.7
11.0
11.5
10.1
10.9
11.0
11.1
10.8
9.0
150
101
154
75
89
11.9
10.4
12.3
8.7
9.9
128
10.8
88
85
80
86
8.5
8.3
8.9
8.5
108
151
162
119
149
163
163
151
Savage's Jerseys, 6
812
860
865
909
925
931
18.8
17.0
17.9
17.6
16.6
19.7
34.7
26.4
34.4
23.4
24.7
32.3
.009
.095
.248
.505
.571
.752
34.5
29.2
36.1
25.0
27.8
30.7
34.6
29.6
35.1
26.6
30.0
33.4
Perkins' Holsteins, 4
1288
1330
1360
1393
22.0
22.0
18.3
21.4
28.6
28.2
24.8
27.8
.336
.781
.432
.371
24.4
24.0
25.3
24.4
25.2
26.0
26.7
25.4
/
Table 21.7
Gross
Aver
age
Live
wt.,
lbs.
Feed
Milk
TDN, FCM,
lbs./ lbs./
day
day
Gross
per year,
dollars*
Live
Aver
wt.
&
day
Not
cor
rected
for
wt.
gain
Continued.
Profit
Em^getic
age
per
wt.
per
1000
cow
lbs.
FCM
gain
843
855
864
887
009
925
947
996
998
1019
12.6
13.8
12.5
13.8
12.4
17.2
13.5
15.9
17.9
14.0
18.0
15.1
15.3
15.8
20.5
17.4
16.6
22.7
21.9
.196
.050
.102
24.7
22.7
29.8
.008
-.133
.029
-.240
.008
27.0
23.4
30.3
29.7
32.8
22.3
20.1
21.1
37.6
26.3
-.109
-.488
-.082
-.060
-.095
.103
-.191
.143
24.6
30.7
32.8
27.6
34.3
32.5
37.4
27.6
33.6
39.8
34.2
27.7
24.7
25.0
34.3
28.4
15.1
14.1
14.6
16.0
17.4
16.9
13.4
14.8
18.3
17.5
16.2
16.5
16.4
18.8
19.2
19.9
18.8
18.4
15.1
19.7
18.6
18.4
20.2
18.2
19.7
20.1
18.6
22.5
.077
22.7
.095
29.6 -.429
17.3
.165
29.4 -.089
35.2
.050
30.2
.278
28.6 -.230
37.8 -.319
32.2 -.071
27.8 -.214
31.4 -.286
23.5
.191
26.6
.223
32.3 -.196
37.0 -.120
27.7
.143
29.8 -.042
20.9
.226
28.2
.161
28.3
.113
25.4
.238
24.7
.226
30.6 -.137
36.1
.117
30.4
.192
.321
31.8
27.9
30.1
38.0
25.4
30.9
33.4
27.6
33.5
33.7
36.0
27.6
33.1
37.0
20.3
31.7
39.1
42.1
27.4
24.4
25.4
33.7
28.9
36.1
38.7
35.5
32.1
35.8
26.9
26.6
31.6
34.9
27.7
30.2
25.9
26.8
28.4
40.3
35.0
37.3
35.2
31.2
34.5
27.6
27.2
30.9
34.4
28.1
30.2
26.7
27.3
28.8
26.6
23.4
31.0
25.9
22.9
31.5
34.4
28.4
34.8
29.0
32.0
33.2
8.6
10.9
11.4
9.8
11.8
11.4
12.5
9.8
11.6
12.9
11.8
9.8
8.6
8.7
11.8
10.1
82
88
136
39
119
164
147
127
176
139
114
139
82
02
131
161
99
117
70
08
104
85
70
124
156
112
130
10.0
10.6
12.6
6.2
11.1
12.8
13.4
12.2
12.7
11.8
11.2
12.1
9.6
9.4
11.1
11.9
9.8
10.7
9.2
9.5
10.0
9.2
7.7
11.1
11.8
10.8
11.2
789
792
793
796
800
14.4
11.1
14.7
12.5
12.6
14.6
12.8
14.2
13.8
15.1
11.8
13.1
15.9
12.5
13.4
14.5
14.2
12.5
14.1
28.5
18.6
25.5
27.5
20.8
22.6
21.8
22.8
23.5
27.6
16.3
31.6
28.8
19.4
24.1
27.8
23.6
25.5
28.6
-.137
-.053
-.286
-.010
-.034
.238
-.060
.006
-.027
-.114
.008
-.893
.137
-^.080
.202
-.398
.115
-.092
-.095
36.9
31.5
32.6
41.2
31.0
28.9
36.2
31.2
31.3
41.4
31.2
30.0
31.8
30.1
31.9
34.1
26.0
31.5
30.1
31.8
33.6
26.0
39.5
34.6
28.6
34.7
45.2
33.9
29.0
33.6
35.9
31.0
38.1
38.0
33.9
31.6
37.5
37.4
Not
cor
rected
for
Cor
rected
for
wt.
per
1000
per
lbs.
FCM
cow
gain
120
75
106
132
83
85
89
89
96
119
55
159
123
67
102
123
94
118
131
876
887
890
898
002
910
915
935
936
989
1013
1046
1071
13.8
14.0
13.6
14.9
13.6
16.8
14.5
16.0
15.3
13.4
12.3
14.8
15.0
14.7
15.4
15.2
14.8
16.2
18.6
13.7
17.6
18.6
15.9
15.8
14.3
13.0
30.9 -.414
25.4
.048
24.1 -.333
29.4 -.184
25.6 -.364
27.0 -.060
22.5
.113
18.5
.198
26.7 -.036
30.0 -.161
28.4 -.143
26.2 -.097
21.1
.143
23.2 -.010
30.1 -.225
21.1
.017
29.2 -.025
23.5 -.080
23.1 -.500
26.0 -.311
24.3
.101
24.6
.018
25.6 -.214
24.0 -.082
22.0 -.103
23.0
.071
23.8 -.131
30.9 -.036
37.0
.024
18.0
.036
31.3 -.074
28.8 -.113
26.1
.250
23.2 -.009
20.4
.148
15.4
.077
40.9
31.1
38.5
31.3
31.2
35.1
35.6
36.5
32.8
36.0
37.7
36.9
30.3
23.0
30.1
34.7
38.1
36.2
26.4
31.9
33.5
27.3
34.2
28.8
32.3
39.6
30.7
30.9
32.7
32.5
26.8
28.5
30.1
35.6
37.1
24.6
33.3
28.9
30.7
27.5
26.8
22.1
30.8
23.6
30.0
34.0
37.3
35.7
27.0
31.8
32.6
27.3
34.1
28.5
30.0
37.6
31.2
30.8
31.8
32.1
26.4
28.8
29.6
35.5
37.2
24.7
33.0
28.6
31.8
27.4
27.4
22.4
148
102
100
131
117
122
88
52
104
131
131
117
72
94
128
75
126
88
95
122
96
98
107
99
.76
85
93
136
168
56
132
108
103
83
71
41
13.1
11.6
11.4
12.2
12.5
12.4
10.7
7.8
10.7
12.0
12.6
12.2
9.4
11.1
11.6
9.8
11.8
10.2
11.3
12.9
10.8
10.9
11.4
11.3
9.4
10.1
10.7
12.1
12.5
8.5
11.5
10.3
10.8
9.8
9.5
7.3
20.0
18.1
34.3
29.9
.000
.019
32.1
30.9
32.1
29.9
140
119
11.2
10.9
96
84
119
26
76
10.6
10.1
11.4
6.8
9.6
7
57
-5
49
2.0
7.5
-1.3
6.6
54
64
42
51
24
8.3
9.0
6.7
7.3
4.9
Eckles' Jerseys, 5
807
824
899
902
952
12.4
11.0
13.8
11.7
9.5
11.6
12.1
10.9
12.7
12.6
14.2
15.3
13.8
15.3
12.7
13.7
14.0
15.1
16.6
16.2
1056
1319
11.4
13.2
10.9
10.3
11.2
10.7
11.2
11.8
9.2
809
809
811
811
817
817
820
820
824
833
836
838
843
845
849
854
855
856
858
859
861
863
867
Eckles' Holsteins, 2
Haecker's Jerseys, 55
634
683
706
734
735
735
752
752
754
758
760
778
782
783
dollars*
Milk
Haecker's Jerseys, 55 Continued
52
90
91
84
98
124
123
84
129
140
141
80
63
67
162
97
33.9.
28.2
30.5
35.8
20.7
31.4
39.4
Profit
per year,
Effic.
wt.
Haecker's Holsteins, 27
781
817
844
872
877
880
887
888
880
006
919
923
975
976
978
985
1086
1095
1106
1114
1117
1128
1137
1273
1292
1298
1315
Energetic
gain
Haecker's Guernseys, 16
766
766
782
790
801
840
Feed
TDN, FCM,
lbs./ lbs./
wt.,
day
day
lbs.
Live
Cor
rected
for
851
15.5
14.9
16.4
9.2
15.0
24.8
22.8
28.6
10.5
21.7
.041
.137
.044
.049
.000
30.0
28.6
32.7
21.3
27.1
30.1
29.2
32.9
21.5
27.1
Hills' Holsteins, 4
1184
1317
1341
1390
11.2
17.2
16.2
18.4
9.4
20.7
11.4
20.5
.487
.752
.893
.307
15.7
22.5
13.2
20.9
17.3
23.4
14.9
21.6
-
Hills' Jerseys, 5
-
885
899
920
929
978
14.0
14.2
15.2
16.6
13.7
17.9
19.4
17.2
19.4
13.6
.627
.548
.613
.410
.458
24.0
25.6
21.1
22.0
18.6
26.6
27.9
22.8
23.2
20.0
852
Table 21.7
Aver
age
Live
wt.,
lbs.
Feed
Milk
TDN. FCM,
lbs./ lbs./
day
day
Live
Profit
per year,
Effic.
dollars*
for
wt.
gain
Live
Cor
wt.
wt.,
lbs.
per
cow
gain
19.4
16.2
19.6
18.9
20.0
16.5
18.9
18.9
19.2
23.1
17.4
20.5
16.6
18.8
22.2
18.4
18.6
22.0
22.3
16.6
21.7
18.1
18.2
19.6
19.3
20.9
16.9
16.1
16.8
19.1
17.9
16.8
20.4
16.2
18.3
20.0
19.7
18.9.
19.7
19.4
19.0
19.5
18.2
20.9
17.7.
19.6
20.4
18.7
17.4
18.6
20.8
20.1
34.5
22.2
32.8
31.3
32.8
24.4
28.4
28.1
30.7
43.2
22.7
34.3
20.1
29.6
41.9
25.9
29.3
41.0
41.0
15.1
39.4
23.3
27.2
31.6
28.4
34.0
22.6
23.4
26.8
28.0
26.4
23.4
33.2
25.1
26.4
38.2
28.7
26.5
31.6
32.3
27.1
31.6
29.6
36.0
23.7
31.2
33.8
27.2
20.6
30.5
34.9
29.2
.155
.192
.075
.367
-.150
.425
-.376
.214
.711
.169
.432
-.316
.335
-.078
.171
.244
.004
.120
-.026
.120
-.030
.530
.150
.398
.384
-.184
.756
.004
.188
1.053
-.489
.249
.087
-.200
-.278
.074
.102
.466
.188
-.278
.015
-.188
-.049
.155
.282
.455
-.116
.587
.327
.098
.216
.470
33.4
25.6
31.4
31.1
30.8
27.7
28.2
27.8
28.9
35.1
24.4
31.4
22.7
29.7
35.4
26.4
29.5
35.0
34.5
21.6
34.0
24.1
28.0
30.1
27.6
30.5
25.0
27.2
30.0
27.5
27.7
26.1
30.5
29.1
27.0
35.7
27.4
26.3
30.1
31.2
26.7
30.3
30.4
32.4
25.1
29.9
31.0
27.4
22.2
30.7
31.4
27.2
33.9
26.3
31.7
32.5
30.3
29.3
27.1
28.5
31.3
35.6
25.7
30.4
23.7
29.4
36.0
27.2
29.6
35.4
34.4
21.9
23.9
25.7
28.5
31.5
28.8
29.9
27.6
27.2
30.8
31.1
26.1
26.9
30.7
28.4
26.2
36.0
28.0
27.8
30.7
30.3
26.7
29.7
30.2
32.9
25.9
31.5
30.6
29.3
23.1
31.1
32.1
28.6
Live
Milk
Feed
Ener
El
TDN, FCM,
lbs./ lbs./
day
day
rear,
ars*
wt.
gain,
lbs./
Not
day
rected
for
wt.
cor
lbs.
FCM
Cor
rected
for
146
73
132
125
130
87
104
102
119
189
70
138
56
115
184
88
112
179
177
49
169
71
99
123
101
134
72
82
139
100
95
78
130
95
92
169
102
90
123
130
94
123
116
149
76
121
134
97
55
121
141
103
Per
cow
wt.
lbs.
FCM
gain
gain
Harrison and Savage's Holsteins, 103
1081
1120
1134
1138
1154
1159
1162
1163
1170
1170
1172
1173
1181
1182
1184
1187
1192
1195
1195
1196
1203
1203
1210
1215
1217
1219
1220
1220
1223
1224
1227
1230
1232
1234
1238
1239
1239
1248
1250
1251
1251
1254
1255
1261
1266
1267
1270
1271
1272
1272
1272
1275
Aver
age
Not
lbs./ cor rected
day rected for
Profit
Gross
Gross
Energetic
wt.
gain,
Continued
Harrison and Savage's Holsteins, 103
11.6
9.0
11.0
10.9
10.8
9.8
10.0
10.0
10.6
12.0
8.5
11.0
7.6
10.6
12.0
9.3
10.5
12.0
11.8
7.0
11.8
8.3
10.0
10.7
9.8
10.8
8.8
9.6
11.4
9.8
9.8
9.2
10.7
10.4
9.6
12.1
9.7
9.3
10.7
11.0
9.5
10.7
10.7
11.3
8.8
10.6
11.0
9.7
7.3
10.9
11.1
9.6
1275
1283
1285
1286
1287
1292
1295
1296
1297
1298
1298
1301
1305
1306
1308
1320
1323
1323
1327
1327
1331
1332
1332
1333
1337
1338
1340
1340
1341
1344
1344
1346
1364
1366
1368
1375
1379
1379
1382
1384
1386
1388
1389
1394
1398
1404
1428
1436
1453
1494
1500
20.7
17.5
20.4
17.9
19.7
20.7
19.5
19.1
20.7
20.4
21.0
21.5
20.8
18.5
17.5
19.6
19.7
20.6
20.8
17.6
21.7
17.3
17.9
21.5
19.4
20.8
18.7
18.0
20.0
18.1
18.8
21.0
18.4
19.5
18.9
19.3
19.1
19.6
18.6
20.9
21.3
21.8
19.9
21.3
20.9
15.8
19.2
19.2
18.4
21.5
21.1
34.6
22.8
32.8
23.2
31.9
35.1
30.4
26.5
32.6
34.9
36.4
39.2
32.4
27.8
22.7
30.8
33.9
32.3
34.1
22.8
39.7
19.8
20.2
35.6
33.5
35.3
26.1
32.8
33.4
22.0
33.8
33.8
26.6
27.6
33.5
29.2
30.6
33.9
22.8
33.3
41.0
38.8
31.7
40.1
35.1
22.9
28.6
28.6
27.4
38.7
36.4
31.3
24.3
30.1
24.3
30.3
31.8
29.2
26.0
29.5
32.1
32.5
34.1
29.2
28.1
24.3
29.4
32.3
29.3
30.7
24.3
34.3
21.4
21.2
31.1
32.5
31.8
26.1
34.1
31.4
22.8
32.8
.443
.244
.229
.105
.169
.045
.263
.131
.470
.613
.065
.090
.384
.511
.756
.131
.176
.214
.128
.150
-.237
-.011
.688
.261
.351
.004
-.045
.327
.192
.853
-.331
.343
.421
.518
.053
.004
.147
-.131
.150
.286
.016
.265
.447
-.690
.271
.637
-.387
.082
29.4
27.1
26.6
32.3
28.4
30.0
32.4
24.3
29.9
36.1
33.3
29.9
35.3
31.5
27.1
27.9
27.8
27.9
33.8
32.3
.494
-.327
-.019
139
32.8
25.1
70
128
30.8
24.6
71
125
30.9
143
32.0
30.0
115
89
26.4
31.0
125
143
34.3
150
32.7
34.4
168
30.4
123
101
29.9
26.8 » 70
29.8
117
140
32.9
123
30.0
31.1
135
24.7
70
33.5
171
50
21.4
23.1
50
31.9
143
139
33.8
144
31.8
26.0
88
35.4
140
32.0
135
.25.3
61
31.6
137
125
30.4
28.5
94
28.2
95
32.5
134
28.4
107
119
29.5
31.9
140
24.7
70
129
30.8
183
36.1
164
34.2
123
31.4
33.0
176
142
32.4
80
29.6
104
26.8
103
28.1
29.5
99
165
32.7
150
32.2
11.0
8.5
10.7
8.4 •
10.7
11.2
10.4
9.2
10.5
11.2
11.4
11.8
10.4
12.7
9.4
10.4
11.3
10.4
10.8
8.4
11.8
6.9
6.7
11.1
11.4
11.2
9.2
11.7
11.1
7.6
11.4
10.4
9.7
9.4
10.3
10.0
10.7
11.3
8.4
10.6
12.2
11.6
10.6
12.1
11.1
9.6
10.0
9.9
9.4
11.5
11.3
* Assuming that price of feed is $1.50 per 100lbs. TDN; price of milk is $2.00 per 100lbs. FCM.
Table 21.8.
Days
Composition of Cow Blood During Fast.
Liîn
Total
fatty
acids
10.0
10.4
10.3
10.1
200
214
Fast
Sterol
Sterol
Iron
Sugar
60
37
66
40
43
37
68
69
48
44
62
65
66
46
61
62
62
Esters
Amino
Acid
N
Mg/100 Cc Blood
Organic
In-
or^nic
acidsoluble P
Ca
C1
3
2.4
7
7
6.4
6.8
6.6
6.4
6.8
267
261
266
279
276
280
276
*
0
u
2i
3^
4^
5^
6
9.6
9.6
9.4
224
186
201
204
95
96
99
96
91
88
88
46
41
7.1
6.1
4
4.9
4.7
4.9
6.8
6.2
6.1
6.1
4.9
4.6
7
3.3
3.2
3.1
3.0
2.6

Milk: Nutritional, Social, and Physiological Aspects

Transcription

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