Abstract #261

# 261
ASAS-EAAP Speaker Exchange Presentation: Statistical approaches to increase resilience of animals towards environmental challenges and to increase homogeneity of animal products.
Han A. Mulder*1, Ewa Sell-Kubiak1, Juanma Herrero-Medrano1,2, Pramod K. Mathur2, Egbert F. Knol2, 1Animal Breeding and Genomics Centre, Wageningen University, Wageningen, the Netherlands, 2TOPIGS Norsvin BV, Beuningen, the Netherlands.

In animal husbandry, there is a growing demand for animals that need less labor and are capable to handle diseases or other environmental challenges. For various markets, homogeneity of animal products is desired and uniform animals would ease management, e.g., less fluctuation in production in spite of challenges. Furthermore, due to globalization of breeding programs animals need to be capable to perform in a wide range of environments. Here we show 2 statistical approaches that can be used to breed for resilience and uniformity: a reaction norm model to breed for resilience and a double hierarchical generalized linear model (DHGLM) to breed for uniformity. Both were applied to reproduction traits such as total number of born piglets and number of piglets born alive in sow lines. For the reaction norm model, we first developed a challenge load indicator to estimate the level of challenge, based on drops in production. Subsequently, we used this challenge load indicator as a covariate in the reaction norm analysis. We found genetic correlations of 0.5–0.85 between healthy and diseased periods indicating substantial reranking of animals, or in other words genetic variation in resilience. We applied a DHGLM to total number born and found substantial genetic variation in residual variance of litter size with a genetic coefficient of variation at variance level of 0.17. Using deregressed variance EBV, we found a few highly significant genomic regions affecting the variance of litter size. These genomic regions could be utilized in genomic selection. Both statistical approaches can yield breeding values that could be used to select for increased resilience and uniformity of animal production. Due to its low heritability, accuracies of breeding values for resilience and uniformity are low, though substantial genetic variation is present. Accuracy of breeding values for these traits can be enhanced by genomic selection.

Key Words: statistical modeling, resilience, uniformity

Speaker Bio
Dr Han Mulder was born in 1979 in the Netherlands. He grew up on a dairy farm where he got interested in animal breeding. He studied Animal Science at the Wageningen University and completed his PhD in Animal Breeding and Genetics in 2007 with Prof. Johan Van Arendonk, Dr Piter Bijma at Wageningen University and Prof. William Hill at University of Edinburgh. After obtaining his PhD, he worked four years as a researcher at the Wageningen UR Livestock Research, mainly on development of software for breeding value estimation. Currently, he is Assistant Professor Animal Breeding and Genetics at Wageningen University and is involved in teaching at BSc, MSc and PhD level. Currently, he is supervising three PhD-students. His research interests are quantitative genetics, optimization of breeding programs and genomic selection. He is particularly interested in unravelling the genetics of genotype by environment interactions, disease resilience and environmental variance. Statistical modelling is a key element in his research. To unravel the genetic architecture of complex traits such as resilience and environmental variance, genome-wide association studies are performed. In his research, he is collaborating with various international scientists and researchers at breeding companies in cattle, pigs and poultry. He is furthermore Vice-President of the Genetics Commission of EAAP.