This research addresses the effect of substitution of imported soybean meal with locally produced yeast protein from Cyberlindnera (C.) jadinii or barley in concentrate feeds for Norwegian Red dairy cows on rumen and milk microbiota, as well as milk quality and milk fatty acid composition.

48 cows were allocated into three groups treated with different concentrate feeds, consisting of a conventional soy-based feed (S), a yeast-based feed (G) and barley-based feed (B). All cows were given grass silage ad libitum in addition to the concentrate feeds, and the feeding experiment was run over 10 weeks.