Liver Abscesses in Feedlot Cattle

TechTALK
Scientific Update from Elanco Animal Health
Liver Abscesses in Feedlot Cattle
Liver abscesses: causes and prevalence
Liver abscesses are lesions found within the liver. These lesions are
scattered throughout the liver and vary in size and number. A typical
liver will have between two and ten abscesses, ranging in size from
less than one inch to more than six inches in diameter. While the
lesions are distributed throughout the liver, larger abscesses tend
to be located close to the portal entry.1
Liver abscess classification
Abscesses are scored 0, A or A+. Livers are removed at harvest and
evaluated for abscess size and number. Livers exhibiting the most
severe abscesses are graded A+. Livers with fewer, smaller and
inactive abscesses are graded A.
Because cattle with liver abscesses often do not show any clinical
signs, abscesses are not detected until harvest.2 Though extremely
rare, a rupture or perforation can lead to massive infection of other
organs and eventually death.2 In most cases, animals will not show
specific clinical signs. However, reduced feed intake, reduced weight
gain and decreased feed efficiency are all results of liver abscesses.2
Incidence factors and management impacts
O
no abscesses
Liver abscesses result from the entry, growth and establishment of
pyogenic bacteria. Bacteria enter the liver through the portal vein, the
hepatic artery, the umbilical vein (only in newborns), the bile duct or
by an infection.
In feedlot cattle, entry via portal vein is by far the most common
route due to the large volume of blood flow and the proximity to the
gastrointestinal tract, a major source of bacteria.3 Liver abscesses can
occur at all ages and in all types of cattle, including dairy cows.2
A
Factors affecting the incidence
of liver abscesses:
• Days on feed (DOF)
• Roughage level in the diet
• Grain type
(barley or wheat, corn, sorghum)
• Duration of grain feeding
• Feed additives
• Bunk management practices
• Steers vs. heifers
• Seasonal and weather conditions
• Geography
A+
one or two small, unorganized
abscesses, or two to four wellorganized abscesses, or abscess scars
one or more large or multiple small,
active abscesses
Figure 1: Bacterial flora of liver abscesses3
Figure 2: The effect of dietary roughage levels on the incidence of liver
abscesses in grain-fed cattle4
40
33
30
26
20
20
10
Fusobacterium
necrophorum
95-100
Arcanobacterium
pyogenes
48
50
Abscesses (%)
Studies have shown that the primary bacterium causing liver
abscesses is Fusobacterium necrophorum, previously named
Sphaerophorus necrophorus.3 In addition to liver abscesses,
Fusobacterium is associated with necrotic laryngitis (calf
diphtheria), foot rot and foot abscesses in cattle.2 The rumen is a
natural environment for the pathogen and can be found not only
in ingested contents, but in the bacterial flora of the ruminal wall.
The second most frequent pathogen isolated from liver abscesses
is Arcanobacterium pyogenes, previously called Actinomyces or
Corynebacterium pyogenes.3
5
0
0
5
10
15
>15
Roughage level
32
Prevalence and factors affecting prevalence
49
0
20
40
60
80 100
Percent
Liver abscesses are secondary to acidosis and rumenitis in the
rumen.4 There has been a correlation shown with rumenitis from
acidosis as an influencing factor for liver abscesses. This means
feeding practices or inconsistent bunk management may prompt
acidosis and rumenitis and eventually lead to a higher incidence of
liver abscesses.3 Rapidly increasing dietary energy through high-grain
feeding, low-roughage diets, and poor bunk management through
irregular feeding (including feed amounts and feed timing) are all
directly linked to higher abscess prevalence.2 Once acidosis has
occurred and damaged the rumen wall, the animal becomes more
susceptible to pathogenic colonies.3
Inclusion of roughage can decrease day-to-day variation in feed
intakes, thereby lowering the occurrence of acidosis and rumenitis,
although not all studies have shown prevalence tied directly to
roughage levels.4 Grains and grain processing that have, or result
in, high rates of starch fermentation, promote greater fluctuations
in rumen pH and intake, leading to acidosis, rumenitis and,
consequently, liver abscesses.3 Examples of these feed types include
wheat, barley and high-moisture or steam-flaked corn.
The prevalence of liver abscesses is approximately 1% to 3% higher
in feedlot steers than heifers, and Holsteins have a greater incidence
than beef breeds.3 This is believed to be based on feed intake. Steers
generally consume more dry matter than heifers, and heifers
generally mature and finish earlier than comparable weight steers,
while Holsteins are typically on feed much longer, with higher total
feed intake.2 Liver abscess incidence can be increased by seasonality
and weather, including heat stress, mud and cold, with the highest
incidence occurring in spring-harvested cattle.
Figure 3: Effect of diet on ruminal F. necrophorum concentration3
70c
70
60
50
MPNx105/g
Others
40
30bc
30
30bc
20
10
10ab
7a
0
Day 0
2
3
17
30
Forage 70% Concentrate 85% Concentrate Forage
(P < 0.05).
abc
Bunk management, including adding feed additives to assist in intake
variation and feed efficiency in high-concentrate diets, can be an
effective tool in limiting acidosis and therefore liver abscesses. Cattle
fed Tylan®, an Elanco feed additive, have shown a 72.5% reduction
in total liver abscesses, while gaining 2.3% faster and converting
feed- to-gain 2.4% more efficiently than cattle not fed Tylan.5 Tylan’s
mode of action has an inhibitory effect on F. necrophorum, primarily
in the rumen. When included in the bunk, Tylan prevents the increase
in ruminal populations of F. necrophorum typically associated with
high-grain diets.5
Liver abscess prevalence in feedlot cattle:2
• Ranges from 1% to 2% to as high as 90% to 95%
Typical feedlot prevalence:
• Between 12% and 32%
Liver abscess prevalance averages for Tylan-fed cattle:6
• Steers
12% – 15%
• Heifers
10% – 13%
• Holsteins 14% – 30%
• (Range: 0% – 95%)
As noted in the section on incidence factors, basic cattle biology
affects the prevalence of abscesses. The cattle’s sex and feeding patterns will greatly impact the prevalence level. As a group, these key
areas have shown the largest correlation with prevalence.
Economic impact
It’s not just a packer issue — liver abscesses reduce feedlot cattle
performance. Abscesses are the leading cause of liver condemnation in the United States. While the liver itself is not a significant
financial loss to a producer, reduced animal performance and
carcass yield have a large economic impact. Cattle with abscessed
livers have reduced feed intake, reduced weight gain and decreased
feed efficiency, leading to a reduced carcass dressing percentage.
Most often, these effects are evident in cattle with the most severe
abscesses.6
Cattle with severe liver abscesses have significantly lower live
weight, carcass weight and dressing percentage, as well as higher
carcass trim. Additional carcass trimming, due to abscess adhesion to the diaphragm and surrounding organs, may be required.
In some instances, condemnation of the entire viscera may be necessary. Accidental rupture of an abscess and carcass contamination can interrupt carcass flow, costing time and labor.6
Holsteins have a greater prevalence because they
Warm carcass weight (lb)
Figure 5: Carcass characteristics of commercially-fed cattle, grouped by
liver abscess score7
Abscess prevalence varies based on:
• Cattle sex (steers or heifers)
• Cattle type
• Feeding behavior
• Maturity
• Retained as replacements
700
695
690
685
680
675
have higher total feed intake than beef steers
(an average of 12% higher).
2
Figure 4: 10-year average of liver abscesses in Elanco-checked cattle
(2003 ­– 2013)6
Dressing percentage (%)
are normally on feed much longer and generally
0
A
A+
0
A
A+
A
A+
64
63
62
61
60
18.5
Total carcass trim due to
abscess (%)
Abscesses (%)
18
17.5
17
16.5
16
15.5
0.4
0.3
0.2
0.1
0
0
Liver abscess score
Holsteins
Heifers
Steers
Industry trends have shown that liver abscesses develop throughout a calf’s life; however, lower incidence levels are observed early
in the feeding period, with abscesses resolving in less than 60
days. In the final 60 days of the feeding period, a higher incidence
of abscess development has been seen. While animal maturity is
a factor affecting prevalence, especially when considering days on
feed, abscesses can form any time after a bout of acidosis causing
rumenitis and F. necrophorum bloom.2
For more information on management practices and Tylan, please
contact your Elanco sales representative. For industry data trends
on liver abscesses, visit www.elanco.us.
The label contains complete use information, including cautions and warnings. Always
read, understand and follow the label and use directions.
Tylan
For reduction of incidence of liver abscesses: Feed continuously
at 8 to 10 g/ton of tylosin (90% DM basis) to provide 60 to 90 mg/hd/d.
Nagaraja, T.G., and M.M. Chengappa. Liver Abscesses in Feedlot Cattle: A Review. J. Anim. Sci. 1998. 76:287-298.
Nagaraja, T.G., K.F. Lechtenberg. Liver abscesses in feedlot cattle. Vet Clin Food Anim. 2007. 23: 351–369.
Nagaraja, T.G., S.B. Laudert, J.C. Parrott. Liver abscesses in feedlot cattle. Part I. Causes, pathogenesis, pathology and diagnosis.
Compendium on Continuing Education for the Practicing Veterinarian. 1996; 18:S230-41.
4
Foster, L. and W. Woods. 1970. Influences of liver abscesses on animal performance. J. Anim. Sci. 31:241.
5
Elanco Study CR-0509. Data on file.
6
Elanco Liver Check Service. Data on file.
7
White, D., and T. Montgomery. The Influence of Liver Abscesses Upon Beef Carcass Yields. Special Technical Bulletin.
Dept. of An. Sci. West Texas State University. 2009.
1
2
3
Tylan® is a trademark for Elanco’s brand of tylosin.
Elanco, Full Value Beef, Tylan® and the diagonal bar are trademarks owned or licensed by Eli Lilly and Company, its subsidiaries or affiliates.
© 2014 Elanco Animal Health.
RUTY 30572-4
USBBUTPX00082