| Development of rumen-protected methionine（RPMet）and slow-release urea（SRU）were made of Met,urea,Acrylic resinⅣ,ethyecellulose and pregelatinized starch by orthogonal experimental design.The degradation rates of RPMet products were determined in rumen and abomasum with Nylon bag method in vivo,and three-step enzymatic hydrolysis in vitro.The release rates of SRU products were determined in different time in vitro through water dissolved method and constant temperature water bath urea enzyme hydrolysis,and the development methods were optimized and the best products were selected.Twelve Little Tail Han-sheep with fistla were selected for 4×4 repeat latin square design,the four dietary treatments with combination RPMet and SRU were:A（0:0）g/kg,B（1.7:3.4）g/kg,C（3.4:3.4）g/kg,D（3.4:3.4）g/kg respectively.The rumen fermentation and nitrogen metabolism indecis were determined.The result show that:（1）The best combination of RPMet was 3 g of the coated materal（Acrylic resinⅣ:ethyecellulose=3:1）and 20 g of the DL-Met materal.Methionine content was 60.00%.（2）The content of the SRU（urea:Acrylic resinⅣ:pregelatinized starch=14:15:5）was 41.18%,with the hydrolysis degree of 60.06%after 120min in water,and the ammonia-release rate was NH3-N 260.01 mg/g SRU during 120 min by urea enzyme in constant temperature water bath.（3）When RPMet and SRU were mixed with different proportion feeding Little Tail Han-sheep,the ruminal concentration of VFA and BCP had no significant different（P>0.05）.The treatment C with RPMet of 3.4 g/kg and SRU of 3.4g/kg was superior to other treatments in these pars of the concentration of NH3-N and pH,as well as different significantly among all groups（P<0.05）.（4）Compared with control group,the nitrogen output was reduced to 14.93%and the retention rate of nitrogen was increased to23.20%in different treatments were fed complex additives of RPMet and SRU.The group C was the best among all treatments with 3.4 g/kg of RPMet and 3.4 g/kg SRU in dietary. |
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