Wat is duurzaam fokken? Grenzen aan selectie?

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Wat is duurzaam fokken? Grenzen aan selectie?
30/10/2013
Wat is duurzaam fokken?
Grenzen aan selectie
Prof. em. E. Decuypere
6 november 2013
Motivation in the past:
increased animal production and productivity
New signal:
“cheap and safe food but not at any cost”
concern/threatening by the public:
 nature of food; food safety?
 are the new (bio)technologies applicable to man?
 animal welfare?
 predominance of economics?
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After World War II
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•
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production
efficiency of production
stock or herd size, farm dimension
specialisation, mechanisation
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Reaction on
industrialisation, specialisation and mechanisation
From animal-machine
Animals as living and sensible beings
Utilitarian approach of animal welfare
Pathocentrism: animal liberation (1975, P. Singer)
Zoocentrism (T. Regan)
condemnation / rejection of animal husbandry or any
instrumental use of animals in its most extreme form
Sustainable animal production
= livestock farming with care
Principles:
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
Health and safety of animals and man: one health
Customised care: ensuring robustness, dignity and integrity
No nuisance from environmental and societal perspective
Credible performance (from socio-economic perspective)
“Implementation of concrete measures is a challenge;
should be in relation to the different types of animal
husbandry practiced in developed and developing countries “
(from Scholten et al.; NJAS 2013)
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What is “careful” livestock farming?
• Ethical concept
• “Layered” meaning
theory of moral circles
• Chance or opportunity to reach caring, sustainable farming
(Nijland et al. NJAS, 2013)
Layers of increasing inclusivity of care on basis of social and temporal dimensions.
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Selection limits for growth and feed efficiency?
Reached because of:
• Exhaustion of genetic variability
quantitative nor molecular genetics give indication
• Unwanted correlated responses
associated with continued selection for production
efficiency
EXAMPLE: unidirectional selection in broiler production
Unwanted responses from selection
EXAMPLE: Broilers
Feed consumption:
95% slaughter population
5% breeder population
In prolific species
poultry, the majo
consumed by the
generation (95%
breeder populatio
Therefore, unwa
responses are m
occur in poultry a
in broiler product
the unidirectiona
Strong unidirectional selection:

More unwanted responses in broiler production
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Energy intake per unit meat output (MJ/kg)
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Extreme growth
Reproductive efficiency
Incompatibility growth/reproduction more pronounced in
• Species with high prolificacy
• Multiparous mammalian farm animals
Therefore:
Focus selection goals:
Slaughter generation
Breeder generation
• Growth
• Feed conversion
• Carcass quality
• Reproduction
parameters
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Further improvements cause dilemmas
3 dilemmas for broiler meat production
(apparent since 1980)
1 fast growth and feed conversion VS. changes in lean/fat tissue ratio
ponderal and energetic efficiency
VS. metabolic disorders
2 of growth and feed conversion
ration (FCR)
3
fast growth and extreme lean
tissue growth
VS. reproductive effectiveness of
the breeder
Dilemma 2: weight vs leg problems in broilers
apparently simple and direct link between
• selection for increased weight at young age
• leg problems (tibia dyschondroplasia, twisted legs, …)
BUT
not so directly mechanistically evident: next slide
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Dilemma 2: weight vs leg problems in broilers
Tibia Dyschondroplasia (TD) and body weight in
ad lib fed broilers selected for 4 generations
for feed conversion efficiency:
for growth upon ad lib feeding:
for growth upon restricted feeding:
FC-line
GL-line
GR-line
Frequency of Dyschondropplasia (TD, %)
TD score
No TD
Light TD
M
Severe TD
No TD
Light TD
Body Weight (g)
sex
F
Severe TD
FC
GL
GR
FC
GL
GR
48
11
9
1948
2138
2264
48
60
56
1998
2211
2133
3
28
35
1975
2063
1998
65
32
27
1728
1908
1913
35
61
56
1775
2006
1901
0
7
18
-
1794
1772
D1/2: Link weight – leg problems?
Appearance of
Selected
Sexe
against twisted legs
against twisted legs
+ for body weight
M
for body weight
against twisted legs
against twisted legs
+ for body weight
for body weight
F
Twisted legs (%)
Dyschondroplasia
(%)
Body weight
1.5
14.1
1808
2.5
21.3
1941
10.5
41.0
1969
0
5.2
1555
0.2
7.5
1677
3.4
15.4
1708
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D3:Fast and lean growth vs reproduction
Domestic poultry: negative relationship between body weight
and reproductive efficiency
• Selection for growth rate in broiler chickens
 reduction of the reproductive capacity of parent stocks
• Parent of meat-type poultry
 genetic potential of fast, efficient growth + reproduction
• Maximize egg and chick production
 quantitative feed restriction
 optimum degree and timing still to be elucidated
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A double broiler breeder paradox
Reproductive
efficiency
BBP
Health and
metabolic
disturbances
Productivity,
resource efficiency
welfare
Animal welfare,
and integrity
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Robustness
Selective breeding in terms of production
+ traits related to health and welfare
 improve “robustness”
Robustness =
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production potential
•
resilience to external stresses
•
physiological ability to maintain or
re-establish homeostatic state or balance
Robustness
• Should be integrated in the breeding goal
• Should not be achieved by violation of the integrity
~ “telos” of an animal
Notion of integrity is a requirement of robustness
(Star et al., 2008)
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Uit ‘De gouden kooi: over het ontstaan van het huisdier’ van A. GAUTIER
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Veranderende houding in de mens-dier relatie
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Verlichting en rationalisme
Wetenschap & Technologie
Industriële revolutie en stagnatie van de landbouw
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Vanaf 1880: impact Amerikaans graan
crisis in de landbouw, de veeteelt terug belangrijk
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Voor en vooral nà WO-II:
mechanisatie
schaalvergroting
specialisatie
intensificatie en instrumentalisatie
van dieren
Veranderende houding in de mens-dier relatie
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Dubbeldoeldieren verdwijnen (specialisatie)
Minder grondgebonden veehouderij
Kennis- en kapitaalsintensief
Aan het oog onttrokken,
Band met individuele dieren verdwijnt
Kloof tussen producent en consument van
dierproducten
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Verscheiden mens-dier relaties
Onderscheiding obv bv diergeneeskundige kosten die men
bereid is te dragen voor een dier
Indeling en definitie van :
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nutsdieren (landbouwhuisdier, proefdier, werkdieren)
gezelschapsdieren
hulpdieren
hobbydieren
schadelijke dieren
exotische dieren
wilde – en jachtdieren
Muskus rat
Paard
Schaap
Konijn
Merkwaardige gelijkenis met de bestiaria van de Middeleeuwen !
Conclusie
Er is een ambigue houding t.o.v. de verschillende
gedomesticeerde dieren, ook m.b.t. eugenetica.
“all animals are equal…but some are more equal than others”
(G. Orwell, Animal Farm)
Ofwel instrumenteel gebruik van dieren
binnen de grenzen van hun “welzijn” en/of “integriteit”
m.a.w. speciesisme is niet moreel verwerpelijk
Ofwel kunnen zij NIET ten bate van de mens worden
gebruikt, en dit voor alle huisdieren inclusief proefdieren,
gezelschapsdieren, …
(en niet opportunistisch enkel voor nutsdieren)
m.a.w. is speciesisme verwerpelijk
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Bedankt voor uw aandacht!
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