Abstract

Somatic cell count is often used as an indirect selection criterion for improving mastitis resistance. However, it may be possible to provide more reliable mastitis breeding values by combining clinical mastitis, and indicator traits; somatic cell count, udder type traits, and milking speed in a multi-trait model. Predictor traits that had genetic correlations with mastitis of >0.20 were selected for the multi-trait analysis. Pedigree and genomic analysis had similar trends in reliabilities for each model tested. When only clinical mastitis was in the model, reliabilities for bulls with pedigree and genomics were 9% and 6% respectively. Adding 305-day somatic cell count to the model increased reliability to 18-37%. Among udder traits, udder depth and rear udder attachment width are the best predictors of mastitis and increase the reliability (21-48%) further when added. The best model included clinical mastitis, average 305 somatic cell count, udder depth and rear udder attachment width. This study opens up for the Australian industry the opportunity to have a more accurate mastitis breeding value to improve mastitis resistance through selection. Keywords: mastitis, somatic cell count, udder, multi-trait, genomic, reliability

Mary Abdelsayed, Mekonnen Haile-Mariam, Jennie Pryce

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume Electronic Poster Session - Biology & Species - Bovine (dairy) 1, , 177, 2018
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