Partitioning of nitrogen net fluxes across the portal-drained viscera in sheep: effect of dietary protein rumen degradability

摘要

Increasing dietary protein supply usually results in a greater portal absorption of amino acids, as long as the energy supply is adequate to support rumen microbial protein synthesis (Raggio et al., 2004). The specific effect of dietary protein rumendegradability is less documented. Initial studies failed in demonstrating a significant effect of an increase in rumen undegradable protein (RUP) on portal a-amino N net release in steers (Huntington, 1987). More recently, an increase in RUP content of the diet increased the portal absorption of amino acids in lactating cows (Blouin et al, 2002), but decreased it in steers (Han et al, 2001). The present study was aimed at determining the effect of a shift in dietary protein digestion from the rumen to the small intestine on N transactions across the different segments of the gut.