The effect of dietary carbohydrate composition on net portal appearance of nutrients and AA liver uptake in dairy cows fed low protein diets

摘要

The efficiency by which raminants transform the feed N into milk protein has been shown (Huhtanen and Hristov, 2009) to be affected by the dietary carbohydrate composition (CHO; starch vs. fiber). However, no evidences exist on the metabolic adaptations that may be involved. A sparing effect of glucogenic nutrients on amino acids (AA) has been traditionally evoked, but this has not been found at the splanchnic level in a recent study using high protein diets (18-19% CP; Larsen and Kristensen, 2012).The aim of this study was to test whether the absorbed nutrients could impact the liver uptake of essential AA (EAA) when starch replaced fiber as the main dietary carbohydrate in low CP dairy diets.