Blood and Milk Protein Polymorphisms in Relation to Feed Efficiency and Production Traits of Dairy Cattle

Abstract

The relationship was studied between 14 biochemical polymorphisms, including 9 blood antigens, serum transferrin, and 4 milk protein systems, and 8 quantitative traits consisting of measures of milk composition, feed efficiency, and consumption of dry matter. Data from 184 Holstein cows fed experimentally during their first lactation were over 10 year-seasons from 14 sire groups on 4 different rations. In all cases, ration differences were large (P<.01). Sire differences were next most important and nearly all significant (P<.05). Season was relatively unimportant as a cause of variation in feed efficiency but showed significant differences (P<.05) in most other traits. A difference in dry matter consumption of 163kg between F antigen genotypes and 193kg between M genotypes was significant (P<.05). Differences in feed efficiency up to 3.4% for S antigen genotypes and up to 2.4% for Lg genotypes were significant (P<.05). Analysis with dry matter consumption as a covariate revealed significant genotype differences (P<.05) of up to 542kg milk, 43kg solids-not-fat, 58kg total solids, 45kg fat-corrected milk yield and 2.4% efficiency for the Lg system. Squared coefficients of correlation revealed a contribution of genotype from 0 to 4.9% of the variation in traits.