Production and composition of milk by dairy cows fed lupin grain or blood meal as protein supplements to hay- or silage-based diets in early lactation

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In 2 concurrent experiments, milk production and composition were measured for 56 days in Holstein-Friesian cows fed concentrate rations based on a mixture of either lupin and barley grains or lupin grain, barley grain and blood meal. In experiment 1, 26 cows were fed 9 kg/day of isonitrogenous concentrate mixtures comprising either 50% barley grain and 50% lupin grain or 70% barley grain, 24% lupin grain and 6% blood meal, together with pasture silage ad libitum. In experiment 2, 32 cows were fed 9 kg/day of isonitrogenous concentrate mixtures comprising either 34% barley grain and 66% lupin grain or 54% barley grain, 40% lupin grain and 6% blood meal, together with pasture hay ad libitum. In both experiments, there were no significant differences between the treatments in the production and composition of milk, or in liveweight and liveweight change. In experiment 1, mean milk yield (L/day), protein content (g/kg), fat content (g/kg), liveweight (kg) and liveweight change (kg/day) were 28.2, 28.5, 40.8, 530 and 0.3, respectively. The corresponding means in experiment 2 were 30.8, 28.6, 39.5, 553 and -0.1. The rate and extent of degradation of nitrogen in the protein supplements incubated in dacron bags in the rumen of steers were lower for blood meal than for lupin grain. It was concluded that, under the conditions in these experiments, when cows were offered a high level of grain concentrate based on barley and lupin grains, as supplements to high quality conserved fodders, there were no benefits to production by replacement of part of the lupin grain by isonitrogenous amounts of blood meal, as a source of undegraded dietary protein.