At Wednesday June 3, Setegn Worku Alemu successfully defended his PhD-thesis, entitled “Indirect Genetic Effects in Group-housed Animals”. During his study, Setegn investigated the possibilities to breed against aggressive interactions in group housed animals. Applying the resulting methods to a population of mink gave promising results. His thesis is a joint thesis of Aarhus University (Denmark) and Wageningen University, and the first joint PhD-thesis at Wageningen University.
Genetic improvement of group-housed animals
In his thesis, Setegn investigated methods for genetic improvement of group-housed animals, in which social interactions may affect productivity and welfare of animals. Resulting methods were applied to a population of group housed mink. In group-housed mink, aggressive interactions and biting behaviour reduce the welfare of the animals. Biting behaviour results in bite marks on the pelts, which can be scored as an indicator of aggressive interactions. Results show that the number of bite marks shows substantial genetic variation, which originates both from the genotype of the victim (so-called direct genetic effects) and from the genotypes of its group mates (so-called indirect genetic effects). These results demonstrate that breeding against aggressive interactions in mink is promising.
Setegn also investigated methods that discriminate between social interactions among closely related individuals versus unfamiliar individuals, and investigated genomic prediction for socially affected traits in laying hens. Results show that statistical models need to discriminate between relatives and unfamiliar individuals, to avoid bias in estimated genetic parameters.