Abstract

Forty-two identical twinsets were milked either once (ODM) or twice (TDM) daily and offered pasture and silage, either to appetite (H) or restricted to 50-60% of this level (L) for the last 5 weeks of the 93/94 season. Pretreatment, uninfected cows produced 8.45+/-0.28 1 milk/d (mean +/- S.E) with a mean somatic cell count (SCC) of 37.1+/-3.3 x 10/3 cells/ml). Milk yields were significantly reduced (P<0.001) by L nutrition and by ODM. LogSCC was significantly increased (P<0.05) by L nutrition, due to reduced milk volumes but was not affected by ODM. Concentration of the serum-derived proteins, immunoglobulin G and bovine serum albumin, increased significantly for L nutrition and ODM. This suggests that involution had been accelerated in these animals, whose average daily milk yield was below 5 1/d. In late lactation milking should be discontinued for cows with milk yields of less than 5 1/d as involution may be initiated below this yield.

MV, Benavides, MY Young, PR Beatson, AP Maher, and TC Reid

Proceedings of the New Zealand Society of Animal Production, Volume 55, , 45, 1995