Study On The Effects Of Rumen-protected Methionine On Amino Acid Metabolism Of Small-fat-tail Sheep

The study was conducted to investigate the effect of different addition levels of rumen-protected methionine on the ruminal fermentation, the apparent digestilities of nutrientsubstance, the blood parameters and the nitrogen metabolism of small-fat-tail sheep. Digestible trial of artificial saliva and nylon bag technique were used to study the stability of rumen-protected methionine in the rumen. Five growing small-fat-tail sheep, fitted with fistula in the rumen, were used in the study. The experiments were performed in Latin square design.The results of digestible trial of artificial saliva and nylon bag technique showed that the stability of RPMet-â… , RPMet-â…¡ and RPMet-â…¢ was better than that of By-pass Met and DL-Met, the effect of different proportion of grease was significant (P < 0.05), the effect of RPMet-â…¡ was best.The different addition levels of rumen-protected methionine did not have a remarkable effect on the ruminal pH and ruminal concentration of NH₃-N, total VFA, proportions of VFA (P > 0.05). The change rule of the ruminal pH and ruminal concentration of NH₃-N, total VFA, proportions of VFA of rumen-protected methionine groups was the same with the control groups. The mean of ruminal NH₃-N concentration of group â…£(the supplementation of RPMet was 0.728%) was significantly lower than that of group â…  (P < 0.05), the bacterial N concentration of group â…£(the supplementation of RPMet was 0.728%) was significantly lower than that of control groups (P < 0.05), the other groups were not significant compared with that of control groups (P > 0.05).The results showed that supplemental rumen-protected methionine increased the retained nitrogen and the nitrogen biological value by decreasing the amount of urine nitrogen and urine urea nitrogen, and the rate of urine urea nitrogen and intake nitrogen. The retained nitrogen of group III(the supplementation of RPMet was 0.485%) was significantly improved by rumen-protected methionine supplementation (P < 0.01).The results showed that the effect of different addition levels of rumen-protected methionine on the apparent digestibility of DM, ADF and NDF was not significant (P > 0.05). The plasma urea-N contents of group III(the supplementation of RPMet was 0.485%) was significantly decreased (P < 0.05) at 4h after feeding. The contents of plasma free Met, He, Leu, Lys, His, BCAA, EAA, and TAA were effected significantly (P < 0.05) as a result of the different addition levels of rumen-protected methionine.The results indicated that methionine was the limited amino acid of the corn-soybean meal diet and the optimal supplementation of rumen-protected methionine in the corn-soybean meal diet under present experiment was 0.485%.