Effect of the level of feed intake on nitrogen entering the small intestine of dairy cows

Abstract

The effect of the level of feed intake on the quantity of protein entering the small intestine was studied in re-entrant cannulated dairy cows fed mixed diets with varying N contents. The degradation of dietary protein in the forestomachs was estimated by two methods, one based on the use of diaminopimelic acid (DAPA) as a microbial marker, the other based on regression techniques. At the higher level of intake, the flow of N into the small intestine as a proportion of the N ingested was higher than at the lower level of intake. This difference could be explained by a decreased degradation of dietary N at the higher level of feed intake. This was thought to be the result of an increased rate of passage of digesta through the forestomachs at a higher level of feed intake.