Milk permeate as a dietary supplement for lactating dairy cows

Abstract

Milk permeate was evaluated as a supplement to replace part of the concentrate or roughage in the diet of lactating dairy cows. The basal d i e t was 6 kg cracked sorghum grain and 6 kg ryegrass dry matter, and permeate was offered ad libitum in place of either 3 kg of sorghum or 3 kg of ryegrass. Intake of permeate stabilised at 30 kg/cow.day (1.7 kg DM) after 6 weeks, with considerable variation among replicate groups. Milk fat percentage was increased from 3.8 to 4.5% (P<0.05) when permeate replaced grain in the diet. Where permeate replaced pasture there was apparently large variation among cows in permeate intake, and this was associated with large variation in the fat and protein contents of the milk. Milk yield (volume) was reduced in proportion to the reduction in total dry matter intake (r = -0.99). With high intakes of permeate, the C18:0 acids in milk fat were reduced and the C16:0 acids increased. It was concluded that permeate could replace about 1.7 kg grain in the diet and that, at this level, there would be advantages in milk fat percentage.