Effects Of Low Protein Diet With Nitrogen Balance On Performance,Digestion And Metabolism And Meat Quality Of Tan Sheep

In this experiment,the fermentation rate of OM and the degradation rate of CP of common feed materials for tan sheep were determined,and the values of FOM,RDP and RENB were calculated,the purpose of this study was to develop a low-protein diet based on the principle of rumen energy-nitrogen balance:on the basis of in vitro experiments,the growth performance of Tan sheep fed a low-protein diet was studied by feeding test,digestion and metabolism test and slaughtering test,the effects of digestion and metabolism and meat quality.Thirty-six healthy three-month-old tan sheep were randomly divided into 4 groups with 9 sheep in each group.On the premise of energy and nitrogen balance,the Diet of control group was formulated according to "Feeding standard for meat sheep"(NY/t 816-2004)and combined with Tan sheep production.Group Ⅰ,Group Ⅱ and Group Ⅲ were fed diets with energy-nitrogen balance that decreased by 1,2 and 3 percentage points compared with the control protein levels,respectively.The main findings are as follows:(1)The results showed that corn,soybean meal,alfalfa and Bran had higher FOM values,while Tofu Dregs had the lowest FOM values.The RDP value of soybean meal and flax meal was higher,while the tofu residue was the lowest.(2)The apparent digestibility of nutrients was increased by feeding low protein diet based on energy-nitrogen balance,and the apparent digestibility of neutral washing fiber was relatively higher in group I(P>0.05).(3)ILow protein diet based on energy-nitrogen balance had significant effects on rumen fermentation and nitrogen emission of tan sheep.The low protein diet(12CP%)could improve the rumen internal environment,decrease the content of NH3-N in rumen,and reduce the nitrogen emission,and increase the biological value of nitrogen deposition and nitrogen(P>0.05).Low protein diets reduced nitrogen emission and increased nitrogen deposition rate.Relatively,12%low CP diet was more favorable for nitrogen deposition.(4)There was no significant difference in the contents of ALB,HDL-C and TG,but the activities of GSH-Px and T-SOD in serum increased gradually,the content of GSH-PX in Test Group I was higher than that in other groups(P>0.05),the content of MDA was decreased gradually,the anti-oxidation ability of tan sheep was improved,the content of IgM in test group I was significantly higher than that in other groups(P<0.05),the immunity of Tan sheep was improved,reduce the incidence of disease.(5)Low protein diet based on energy-nitrogen balance had no significant effect on head,hoof and bone weight of tan sheep(P>0.05),but had no significant effect on GR,eye muscle area and tail fat(P>0.05).The dressing rate of group I was higher than that of the other three groups(P>0.05),and the flesh color of Group III was significantly higher than that of the control group(P<0.05).