|Chitko Mckown, Carol|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: March 10, 2013
Publication Date: N/A
Technical Abstract: Infectious disease of livestock continues to be a cause of substantial economic loss and adverse welfare. Breeding for disease resistant livestock could improve both the economic burden and animal welfare. We aim to identify key genes and pathways that control variation in immune response; knowledge that may aid both breeders and vaccinologists. The herd used during this investigation (n=3500) were the product of multiple-sire matings of crossbred cows to F1 bulls of varying half-blood composition. The resulting animals consisted of variable fractions of 9 breeds: Angus, Hereford, Red Angus, Brahman, Charolais, Gelbvieh, Limousin, Simmental, and MARCIII composite (1/4 Angus, 1/4 Hereford, 1/4 Red Poll, 1/4 Pinzgauer). Each animal was vaccinated for the five major viral causes of BRD: BRSV, PI3, BVDVI/II and IBR. Multiple immune related phenotypes (counts of: white blood cells, neutrophils, lymphocytes, monocytes, eosinophils and basophils) were measured pre and post booster vaccination (a delta measurement was also calculated [post-pre]). Every animal in the herd was also genotyped with 50K SNP, with founding sires genotyped with 770k SNP, allowing the imputation of every animal to density of 770k SNP. After a genome wide association study was conducted, regions associated with the immune responses were discovered. Twenty-two SNP in the current study were associated with levels pre, post and delta basophils and post eosinophils, at the genome wide significance level. These SNP were located on 11 separate chromosomes, at least in part, highlighting the complexity of eliciting an immune response. Further, each trait had at least one SNP associated with it at the chromosome wide significance level. In addition, the estimation of SNP effects in different breeds was possible due to the multi-breed composition of the herd. We conclude that key pivotal pathways may be shared in eliciting and maintaining an immune response to differing types of antigens.