Suitability of lupin and pea seeds as a substitute for soybean meal in high-producing dairy cow feed

Abstract

Two experiments were conducted to investigate the substitution of soybean meal by coarsely ground lupin and/or pea seeds in high-producing dairy cow feed. In experiment 1 (Exp. 1), four Holstein dairy cows (35.9 2.2 Ld -1 milk) were put on a control diet consisting of 50% maize silage, 11% grass silage and 36% concentrates on a dry-matter (DM) basis. Soybean meal was partially replaced (75%) by lupin, pea and a mixture (1/1, DM) of lupin and pea on a DM basis, following a 4 4 Latin square design. Milk production was lower with pea seeds, intermediate with a lupin/ pea seed mixture and higher with lupin and soybean meal diets. Milk fat percentage increased with the lupin diet, which induced a lower proportion of medium-chain fatty acids and a higher proportion of long-chain fatty acids in the milk compared to the pea diet. In experiment 2 (Exp. 2), six Holstein dairy cows (36.0 4.9 Ld -1 milk) were put on a control diet consisting of 47% maize silage, 7% grass silage and 42% concentrates on a DM basis. Soybean meal was totally replaced by lupin or a lupin/pea mixture (1/1, N) on a nitrogen basis, following a duplicated Latin square design (6 animals 3 diets). Standard milk production did not differ with the dietary protein source but milk fat percentage was reduced with the lupin diet. This effect, not observed in Exp. 1, was probably related to the lipid content of the lupin diet. Nitrogen efficiency was not modified by the protein source. The results also showed that a high ingestion of lupin seeds induced a lower milk 6/3 ratio and C 18:2 content. In conclusion, coarsely ground lupin seeds can efficiently replace soybean meal in high-producing dairy cow feed.