Impact of crude protein content in silage and concentrate on protein and fatty acid profiles in bovine milk

摘要

Two concentrates, one protein-rich and one based on cereals, were combined with two silages with a crude protein content of 17 and 13% of dry matter (DM), respectively to give four different diets for dairy cows. Milk content of caseins (α_S1-, α_S2-, β-, and κ-casein) and whey proteins (α-lactalbumin (α-LA) and β-lactoglobulin (β-LG)) and the fatty acid profile of milk were analyzed before the start and on four occasions during the experiment. Milk analyses showed that diet had no influence on the protein profile of the milk. However, a significant increase of α-linolenic acid, 13 and 39%, was obtained on the high protein concentrate feed and on the silage higher in crude protein, respectively. Cows on the protein-rich concentrate diet increased the proportion of conjugated linoleic acid by 53%. Linoleic acid was not affected by the diet.