Abstract

Two trials were conducted to define the variation in concentrations of b-lactoglobulin (b-LG) in bovine milk following different milking intervals. In the first, milk samples were collected from three herds of 20 cows. At the time of sampling in early summer, one herd was in each of early, mid and late lactation (30, 120 and 210 days post calving, respectively). Average b-LG concentrations were 41, 37 and 50% higher (p<0.05) after a 16h than 8h milking interval for early, mid and late lactation, respectively. In the second trial, bulk milk was sampled from four herds of 12 cows. All cows were at the same stage of lactation and the milking interval was 16:8h. Samples were collected on three separate occasions when cows were on unrestricted pasture intake and once when intake was restricted by 50%. On unrestricted pasture intake, concentrations of b-LG were 11% higher in milk collected after 16h than 8h milking interval, whilst on restricted intake, concentrations were 44% higher. There were no differences in concentrations of a-lactalbumin (a-LA). Both trials show a significant difference in b-LG levels in milk collected after 16h versus 8h milking interval, although only 71% of all samples collected in the first trial exhibited this difference and it was less in the second trial using bulk milk.

RD, McLaren, MJ Auldist, and CG Prosser

Proceedings of the New Zealand Society of Animal Production, Volume 58, , 49-51, 1998