Lack of association between bovine major histocompatibility complex class II polymorphism and production traits.

The relationship between bovine major histocompatibility class II polymorphism and fertility, growth, and milk production traits was investigated. A group of 196 young breeding bulls of the Swedish Red and White breed, selected from the yearly batches of bulls undergoing progeny testing, was typed for polymorphism in the class II DQ subregion using restriction fragment length analyses. The fertility traits included the bull's own fertility, measured as relative nonreturn rates, daughter fertility, measured as number of inseminations per service period, and daughters' frequency of veterinary treatment of cystic ovaries. Milk production traits included milk production and percentages of fat and protein measured on daughters during first lactation. In addition, measures of individual growth rate of the bulls were included. Despite the relatively large amount of data analyzed and the accurate measures on milk production traits, no convincing association was revealed between DQ polymorphism and any of the traits investigated. The results suggest that the bovine class II polymorphism is selectively neutral in relation to the analyzed growth, fertility, and milk production traits.