The Effects Of RPAA On Digestion And Metabolism And Their Optimal Supplementation Of Beef Cattle

The study were conducted to investigate the effects of duodenal DL-Met gradient infusion on the digestion and metabolism of steers and optimal dosage of Met, the stability and metabolism of DL-Met, MHA, adsorptive-MHA (A-MHA), grease-embedded-Met (G-Met) and fatty-acid-embedded-Met (FA-Met) in the rumen and post rumen, the effect of Met administration in the rumen on the digestion and metabolism of steers and optimal administration dosage of RP-Lys. Crossbred (LimousinxLuxi) steers, fitted with fistula in the rumen, the proximal duodenum and dismal ileum, were used in the study. The experiments were performed in Latin square design.The results showed that the apparent digestibility of nitrogen in the small intestine.the retainded efficiency of nitrogen and ADG were significantly increased while plasma urea-N contents were significantly decreased (P < .05) by duodenal DL-Met gradient infusion. When different quantity Met were infused into the duodenum the contents of plasma free Ser Met Ile Leu Lys and Cys would be effected significantly(P < .05). When the dosage of Met that infused into the duodenum in a gradient manner was 13 g/d, there were obvious increase(P < .05) in Met, Cys, Pro, Lys, EAA and TAA flows in the duodenum, the apparent digestilities of Asp, Thr, Ser, Glu, phe. His, Arg in the small intestine could also be increased(P < .05), while the apparent digestility of Pro in the small intestine should be decreasd(P< .05). The apparent digestibilities of EAA such as Lys, Met, Leu, Ile, His, Val, Arg, Thr were greater than NEAA. So we can see that duodenal DL-Met gradient infusion can improve the balance of amino acid and the utilization of amino acid. At the same time, it led to higher RN. As limited amino acid the optimal accession quantity of DL-Met under present experiment was 13g/d.Small-nylon-bag method was used to study the stability and metabolism of DL-Met, MHA, adsorptive-MHA (A-MHA), grease-embedded-Met (G-Met), and fatty-acid-embedded-Met (FA-Met) in the rumen and post rumen. The results indicated that DL-Met was not suit for feeding ruminant animals directly; the stability of FA-Met was better than that of DL-Met. A-MHA and G-Met were better than FA-Met. The disappearance rates of different RP-Met in post rumen, small intestine, large intestine, whole gastrointestinal tract were similar, and so were the utilization rates of different G-Met in the gastrointestinal tract.The steers were administrated with DL-Met( II), G-Met(III) and A-MHA(IV) in the rumen respectively. The results showed that ADG, DN, RN and RN/DN of group III were greater (P < .05) than those of groups. The apparent digestibilities of Thr, Ile, Tyr, Phe, Pro, Cys in group III were greater (P < .05) than those of group I , while Ala was lower (P < .05) than those of group I ;the contents of plasma urea-N, plasma TAA, EAA, BCAA, Ser, and Met were lower (P < .05) than those of group I .The Phe and Met in rumen liquid microorganism and the Leu and Ile in rumen chyme microorganism of group III and group IV were greater (P < .05) than those of group I . From the above it revealed that the balance of amino acid in the small intestine and the utilization of amino acid and the contents of part EAA in rumen liquid MCP were improved by rumen RP-Met administration. The optimal RP-Met under present experiment was the G-Met.Under the condition of the requirement of Met being contented, the steers administrated with 15 g/d RPLys in the rumen had the highest (P < .05) ADG, RN, DN, RN/NI, and RN/DN and urine urea nitrogen vice versa; As limited amino acid the optimal dosage of RP-Lys may be 15 g/d.