Influence of continuous intravenous lysine and methionine infusion onN-balance in growing sheep fed diets that differ in ruminal degradableprotein

摘要

The effect of continuously infused lysine and methionine with glucose on nitrogen retention in young wethers (average liveweight 31.3 kg) fed diets with different protein degradation in the rumen in two 4 x 4 Latin squares design was investigated. The wethers of a particular Latin square were fed at a level of 1.2-times their maintenance energy requirement either with a diet based on ground barley and urea (B+U), with high degradable intake protein (HDIP) or a diet based on cracked maize and maize gluten meal (M+MGM), with high undegradable intake protein (HUIP). The wethers of each Latin square were continuously infused (jugular) with control solution (Control), or with L-lysine (Lys), DL-methionine (Met) or their combination (Lys+Met). Infusion rates for the above mentioned amino acids were 3.0, 1.5 and 3.0 g+1.5 g lamb(-1) day(-1), respectively, estimated to be about 50% of maintenance. Glycine was added to the infusion solutions to equalise the total N infused. Glucose(12 g kg BW(0.75)d(-1)) was also supplemented in the infusion solution to minimise endogenous gluconeogenesis.