Associations of beta-lactoglobulin variants with milk production, milk composition and reproductive performance in milk sheep

RFLP analysis was used to genotype beta-lactogtobulin for 839 East Friesian milksheep from 6 flocks in Austria. Allele frequencies were: beta-lactoglo bulin A 0.82 and beta-lactoglbuliin B 0.18. Over 3 years production traits of 1.783 lactations (standardized lactation, 240-days) were measured. The r elationship of the genetic variants and yield of milk, fat, protein, age of the ewe and number of born lambs was investigated. Significant correlation s between genotype and production traits were not observed. The beta-lactog lobulin variant BE was associated with higher yields of milk and fat-protei n. AA-milk contained higher concentrations of fat. BB-animals showed the lo ngest lactation period. In the first lactation sheep with beta-lactoglobuli n variant AA were superior with higher yields of milk and fat whereas genot ype BE dominated the following milking periods (2(nd) to 6(th)).