The effect of protein supplements on the production and composition of milk from dairy cows fed high levels of grain with pasture silage in early lactation

Abstract

Milk production and composition were measured for 42 days in 76 Holstein-Friesian dairy cattle in early lactation fed a 3 : 1 barley-lupin grain mixture with protein supplements of lupins, meat meal, blood meal, or cottonseed meal. The crude protein content of all grain-protein supplement mixtures was 21%. The cows were fed 9 kglday of the grain-protein supplement mixtures, and perennial ryegrass-subterranean clover pasture silage was available ad libitum. When data from all cows were analysed, no significant differences were recorded in the production and composition of milk from cows fed the different protein supplements. However, analysing only data from those cows producing >25 L/day, there was a significant (P<0.05) difference in the production per day by cows fed blood meal (29.6 L milk, 0.81 kg protein) compared with those fed lupins (27.0, 0.76), meat meal (26.9, 0.75), or cottonseed meal (27.6, 0.75). The rate and extent of degradation of nitrogen in the protein supplements incubated in dacron bags in the rumen of steers was significantly (P<0.05) less for blood meal than for the other protein supplements. Under the conditions of this experiment, blood meal was a more suitable protein supplement than lupins for the production of milk and milk protein in dairy cows in early lactation producing >25 L milk/day.