Nitrogen emission and lactation characteristics of Holstein-Friesian dairy cattle fed low-protein diets with and without branched-chain volatile fatty acid supplementation

O were not affected by dietary CP content. Hence, it can be concluded that when the dietary CP content decreased from 167 to 154 g/kg DM, BCVFA supplementation did not counteract the negative effects of protein-limitation on milk and component yields. This may suggest that the low-protein diet may not have provided adequate rumen N to support increased microbial protein synthesis from BCVFA or that the effect of a lower metabolizable protein supply overruled any effect of supplemental BCVFA.