Abstract

The association between b-lactoglobulin (β-LG) variants and milk composition throughout lactation was determined by sampling from 44 Friesian cows (22 homozygous for b-LG AA and 22 homozygous for b-LG BB) in early (day 6 postpartum), established (1-3 months postpartum) and late lactation (on the day of drying off). Results indicated that differences between β-LG AA and BB phenotype milk (expressed as a percentage of the level in phenotype AA) in concentrations of bovine serum albumin (BSA; -15.9%, -32.0%, -42.5%) and b-LG (5.9%, 16.0%, 32.2%), in early, established and late lactation respectively, increased steadily as lactation progressed. The differences in a-lactalbumin concentrations were less variable (1.2%, -9.0%, -9.1%). These results provide new evidence that compositional differences are not seen between b-LG AA and BB phenotype milk until established lactation.

S-A, Turner, MJ Auldist, PC Molan, and CG Prosser

Proceedings of the New Zealand Society of Animal Production, Volume 58, , 52-54, 1998