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The role of breeding and genetics
in animal welfare
T. Bas Rodenburg, Animal Breeding & Genomics Centre
Simon P. Turner, Scottish Agricultural College (SAC)
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Introduction
Domestication startedthousands of years ago
Past 50-60 years:
intensive selection forincreased production
Genetic selection
● Contributed to welfare issues: lameness broilers
● Can also be used to alleviate welfare issues
(Rauw et al., 1998)
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Variation between species
Domestic species vary greatly in:
● Traits under selection
● Selection intensity
● Application of breeding technologies
Intensive versus extensive systems
Differences in genetic progress
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Focus on intensive sectors
Breeding-related welfare challenges
● Mainly associated with the
highly selected poultry,
dairy and pig sectors
Also play a role in the extensivelymanaged breeds
● Increased lambing rate:
reduction in lamb survival
●
Calving difficultiesin beef cattle
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Variation within species
Breeds and hybrids
Generalist- versus specialist-type
● Intensive production: generalist-type
● Rare breeds: specialist-type
Rare breeds more hardy inspecific environments
● Easy care sheep
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High-yield crosses
Pigs and poultry: pure-bred lines used for selection
● Commercial product is a hybrid cross (4 lines)
● Female lines: reproductive traits
Male line: fast growth, low feed conversion
Sheep production: low-maintenance ewes
● Mated to less hardy,
but more productive sires
● Crossbreds for fatteningon lower ground
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Selection for increased growth in broilers
Extremely successful:
● 25 to 100 grams/day
Increased incidences of● Lameness
● Ascites
● Sudden death syndrome
(Knowles et al., 2008)
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0
5
10
15
20
25
30
35
40
1 6 14 16 21 29 42 49
Age (days)
T e m p e r
a t u r e
Control
Test
Van Horne et al., 2004
Suboptimal conditions
(van Horne et al., 2004)
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Slow growing Fastgrowing
A B C
Sudden Death 0 1.7 1.7 0
Heart Failure 0 0 1.7 1.3
Ascites 0 0 0.8 13.8
Total Heart +
circulation
0 1.7 4.2 15.0
Van Horne et al., 2004
Mortality
(van Horne et al., 2004)
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Slower growing broilers
Grow to slaughter weight in 56 rather than 42 days
Much less welfare issues
●
Reduced mortality● Reduced lameness
● Reduced footpad dermatitis
Limited feed restriction required inparent stock (dwarf mothers)
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Dairy cows
Selection for increased milk yield
● Decreased fertility and longevity
● Increased lameness
● Increased metabolic problems
● A higher incidence of mastitis
Future: automatic collection ofdata in/around milking parlour
● Incorporate informationin breeding program
(Oltenacu and Broom, 2010)
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Selection enhancing undesired behaviour
Genetic correlation tail biting with (Breuer et al., 2005):
● Lean tissue growth rate (0.27)
● Backfat thickness (-0.28)
Selection for early sexual maturation laying hens
● Correlated to increased feather pecking
(Jensen et al., 2005)
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Selection for improved welfare
Direct selection against undesired behaviours feasible
● Aggression in pigs (Turner, 2011)
● Feather pecking in laying hens
(Kjaer et al., 2001)
Helpful in understandingbehaviours
● Unravel underlying
mechanisms0
1
2
3
4
5
0 1 2 3
Generation
F r e q u
e n c y
o f f e a t h e r p e c k i n g
High feather
pecking
Low feather
pecking
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Breeding for improved group performance
Traditional: focus onindividual performance
Risk to select animalsthat are harmfulfor group performance
Alternative methods needed that take groupperformance into account
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23 5.7
15 15
19 6.3
26 6.5
Group Selected
Per
cagePer
individual
Eggs
Individual Selected
Group selection (Muir, 1996)
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Cumulative mortality (Muir, 1996)
0
50
100
150
200
250
300
350
400
450
1 8 2 1 2 4 2 7 3 0 3 3 3 6 3 9 4 2 4 5 4 8 5 1 5 4 5 7
AGE (WEEKS)
CONTROL
GROUP SELECTED 7
COMMERCIAL
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New methods
Kin selection method
● Combine individual performance
with information from sisters in
group housing (Ellen et al., 2007)
Social breeding values
● Estimate the genetic effect an animal
has on the performance of its group mates
(Muir, 2005; Bijma et al., 2007)
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Kin selection on low mortality
White leghorn line
(Ellen et al., 2007)
Control line:• Selection candidate individual• Selection on production
Low mortality line• Selection candidate individual• Selection on production• Full sisters in group (4)• Selection on low mortality
Non-beak trimmed in cages:mortality due to cannibalism
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Results after one generation
0
10
20
30
40
50
Control Low
M o r t a l i t y %
Generation 1
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Effects on behaviour
Birds selected on low mortality:
● Less fearful
● Young age
● Adult age
● Reduced stress response
● Less cannibalistic pecking
● Changes in the serotonergic system
compared with control birds
(Bolhuis et al., 2009; Rodenburg et al, 2009ab;Nordquist et al., 2011)
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Role of the serotonergic system
Feather pecking is redirected foraging
● In response to fear and stress inducing stimuli
The serotonergic (5-HT) system central role:
● Involved in coping with fear and stress,
● Involved in foraging and in feather pecking(van Hierden et al., 2004)
Selection for low mortality: changes in the peripheralserotonergic (5-HT) system (Bolhuis et al., 2009)
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FP and the serotonergic system
Associations between feather pecking and genesinvolved in the serotonergic system
Comparison of lines selected
for high an low FP
Frequency differenceDEAF1 polymorphisms
● Regulatory gene
serotonergic system
(Flisikowski et al., 2009)
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FP and the serotonergic system
Association study onfeather damage
●
Nine different linesof laying hens
● Brown and white lines
●
Association between feather damage and HTR2C● Receptor gene serotonergic system
0
0.2
0.4
0.6
0.8
1
Brown White
A l l e l e
f r e q u e n c y
(after Biscarini et al., 2010)
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Plumage condition
(after Uitdehaag et al., 2008)
4
4.5
5
5.5
Brown White
P l u m a g e c o n d i t i o n
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Fearfulness
(after Uitdehaag et al., 2008)
0
0.1
0.2
0.3
0.4
23 46 69
P r o b a b i l i t y
o f s h o w i n g a
f e a r f u l r e s p o n s e
Age (weeks)
BrownWhite
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Coherent with selection experiment
Birds selected on low mortality
● Less fearful
● Reduced stress response
● Less cannibalistic pecking
●
Changes in the serotonergic systemcompared with control birds
Further developing genetic fingerprint associated with FPwill enhance possibilities for genetic selection
(Bolhuis et al., 2009; Rodenburg et al, 2009ab;Nordquist et al., 2011)
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Aggression in pigs
Observed after mixing but also under stable conditions
● Mixing is a routine procedure
Results in skin lesions
Aggression can negativelyaffect performance
(Turner et al., 2006)
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Breeding against aggression
Technically possible
● Fighting and bullying have
moderate heritabilities in pigs
(between 0.17 and 0.43)
● Number of resulting skin lesions(between 0.21 and 0.26)
(Lovendahl et al., 2005; Turner et al., 2006; 2009)
Genetic correlations indicate that skin lesions can be
used as an indicator of being aggressive
(Turner et al., 2006)
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Effects of selection
Genetic correlation between aggression around mixingand under stable conditions: selection reduces both
Associated changes in:
● Genes involved in coping
with stress (HPA-axis)
● Brain gene expression
vasopressin and serotonin
●
Altered cholesterol metabolism
(Murani et al., 2010, 2011; D’Eath et al., 2005)
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Effects of selection
Selection might alter basic pathways that govern a rangeof biological functions
● Aggressive animals also
faster to enter weighing
scale (D’Eath et al., 2009)
No differences in general activitylevels to underlie reduced aggressiveness
● No adverse effects on lean tissue growth
(Turner et al., 2006)
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Social breeding values
Traditional selection methods lack attention for socialinteractions
Social genetic effects contribute profoundly to geneticvariance in growth rate in pigs
(Bergsma et al. 2008)
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Number of lesions
De Vries, unpublished results
Post mixing Steady situation
HighSBV
Low SBV High SBV Low SBV
Anterior 17.03a 11.59b ** 4.27 4.77Middle 7.80 7.46 1.84 2.33
Rear 1.95 2.10 0.90 1.28
Back - - 1.08a 1.63b *
* p < 0.05, ** p < 0.01
Similar results found by Canario et al. (2008)
(Rodenburg et al. 2010, Canario et al. 2008)
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Effects on manipulative behaviour
High SBV pigs showed:● Showed 15% more
comfort behaviour
● Spent 14% less time
on ear biting
● Spent 35% less time
on chewing objects
● Had less tail damage
This may indicate that low SBV pigs have a strongertendency to perform oral manipulation
(Camerlink et al. 2012, Ursinus et al. 2012)
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Conclusion selection experiments
Scope to use novel selection methodsto improve welfare of group-housedanimals
● Kin selection laying hens
● Social breeding value pigs
Progress may be slower than expected
● Hens: easier to select for increased damage
● Pigs: realised genetic progress relatively small
Increased understanding of genetics of social behaviour
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General conclusion
Breeding and genetics: important role in the welfare ofdomestic animals
If focused only on
increasing production:● Clear risk of increasing
welfare problems
Wider perspective is needed that encompasses both
production and welfare traits
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General conclusion
Genomics era could offer opportunities● More precise information on the biological
impact of certain breeding decisions
Help breeders to make more informedchoices in their selection programs
● Facilitate selection for complex
behavioural traits:
5-HT polymorphisms
● Genetic fingerprint: targeted
genomic selection approaches
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Open to collaboration!
Main topic:
● Improving social behaviour in group-housedanimals by genetic selection and improvingearly-life conditions
Future position (from 1 August):
● Assistant Professor Behavioural Ecology at WUR
● Focus on research + teaching
applied animal behaviour and welfare
●
Centre of Animal Welfare and Adaptation(CAWA)
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Thank you!
This paper will be published in theJuly 2012 issue of Animal Frontiers
(special issue on Animal Welfare,edited by Don Lay)
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