Selecting for Robustness in Pigs Pramod Mathur, Saskia Bloemhof, Hamed Rashidi, Egbert Knol NSIF: Nov 2012
Why robustness? Globalization of pork production Global warming Easier spread of diseases and reduction of antibiotics Feed and Labor shortage and costs Genotype x environment interactions Environmental sensitivity
How to define robustness? A number of factors Changes in climate, feed, labor, Variation in production: Within sow Between sows Between weeks / seasons Diseases or health challenges Heat stress.
How to measure robustness? Adaptability to stressors Parasite burden Immune parameters Heat load Metabolic rate Productive adaptability to stressors Ability to keep up production in spite of stressors Fitness (reproduction) Production
Disease tolerance as an indicator trait for robustness
How to identify disease phases? Most farms: No data on: virus load lymphocyte count immune parameters Lots of data Production and reproduction
Weekly production 14 12 Number piglets born alive 10 8 6 4 2 Number piglets born alive 0 2004 2005 2006 2007 2008 2009 2010 2011 2012 Year-weeks
Outbreak detection NBA: Number of piglets born alive
Outbreak detection 14 12 Number piglets born alive 10 8 6 4 2 Healthy Diseased 0 2004 2005 2006 2007 2008 2009 2010 2011 2012 Year-weeks
Outbreak detection 14 12 Number piglets born alive 10 8 6 4 2 Healthy Diseased Virus isolation 0 2004 2005 2006 2007 2008 2009 2010 2011 2012 Year-weeks
Relationship between performance in healthy and disease phases Variance components Number piglets Born Alive Mummified piglets Still-born piglets Bivar. Reac. Norm Bivar. Reac. Norm Bivar. Reac. Norm Healthy phases 10.42 10.43 0.88 0.84 1.61 1.54 Disease phases 21.03 20.11 1.02 0.94 6.78 4.10 Correlation 0.89 0.87 0.85 0.84 0.64 0.64 Bivariate model: Performance in healthy and disease phases as different traits Reaction norm: Quantification of severity of the disease
Disease tolerance Disease outbreaks can be detected using data models Disease leads to higher variance Higher host genetic variation available Opportunities for selection to reduce losses
Heat tolerance as an indicator trait for robustness
Farrowing rates of two lines 32,631 records from 11,935 sows in Spain Source: Bloemhof et al., JAS 2008
Genotype x environment interactions Line Constant UCT Slope D 0.84 19.2-0.01 I - - - Source: Bloemhof et al., JAS 2008
Selection in a different environment Correlations between performance at different production levels Example: Litter size Reaction norms approach and genomic selection
Robustness to heat stress Differences between genetic lines in heat tolerance Significant genotype x environment interactions Selection in a different environment can lead to reduction in performance
Robustness: Undisturbed production
Problem free finisher production Birth Weaning 1 2 Finishing Problem free finishing = 100% 1. Survival from birth to Weaning = 100% 2. Survival from weaning to finishing = 100%
Problem Free Sow Production 1 2 4 3
Merry go round Producers like sows that keep up producing from one cycle to the next without problems
Problem Free Sow Producton Problem freeness = 100 when: 1. Interval weaning first insemination <= 7 days 2. Non-return rate = 100 % 3. Farrowing rate = 100 % 4. Selection for next cycle = Yes Else: problem freeness = 0
Heritability estimates Trait: Heritability (S.E) Problem free sow production 0.06 ±0.01 1. Timely in heat 0.18 ±0.02 2. Non return to estrus 0.06 ±0.02 3. Farrowing rate 0.08 ±0.02 4. Selected for next cycle 0.04 ±0.01 Total number born 0.10 ±0.01 Born alive 0.08 ±0.01 % Born alive 0.04 ±0.01 Number still born 0.06 ±0.01
Genetic correlation Problem free sow production No heat stress Heat stress Heritability 0.05 ±0.01 0.08 ±0.01 Genetic variance 0.06 ±0.02 0.12 ±0.02 Phenotypic variance 1.25 ±0.02 1.51 ±0.02 Genetic correlation 0.93 ±0.07
Concluding remarks Robustness in pigs can be measured as productive adaptability to stressors There is evidence for strong genotype x environment interactions Selection in a different environment can lead to reduction in performance Need to consider robustness in breeding goals
Health Selection and for Environment robustness Platform Breed pigs with enhanced ability to keep up performance in spite of challenges Thanks..!