Effects Of Concentrate Supplementing Level On Performance And Ruminal Environmental Parameters Of Fattening Tibetan Sheep

In a single factorial arrangement of treatments, twenty-four eighteen-month old castrated Tibetan sheep with similar live weight were randomly divided into three groups (Ⅰ,Ⅱ,Ⅲ). Tibetan sheep were given a basal diet(oat hay)with concentrate supplied at 150g/d, 300g/d, 450g/d respectively to study the effects of different concentrate supplementing levels on the production performance, digestion and metabolism of diet nutrients and changes of rumen enviroment.The results showed as follows:1.With increasing dietary concentrate level,the intake of diet and average daily gain(ADG) were increased significantly(P<0.05). Whereas no significant change was found in oat hay intake(P>0.05). The concentrate and diet conversion efficiency reached highest point at 300g/d concentrate level. The daily gain of each group tended to decrease at the latter fattening period. The days of fattening Tibetan sheep should be 45d to 50d at different concentrate level. Gain profit of groupⅡ was highest among three groups.2.With increased concentrate level, apparent digestibities of DM,OM,nitrogen,Ca and P were increased. The intake of nitrogen ,fecal and urinary nitrogen ,retention rate of nitrogen were increased. Retention rate of nitrogen was no significant difference between 300g/d and 450g/d concentrate level(P>0.05). While concentrate level rised(P<0.05), the daily intake, apparent digestibity and retention rate of energy were increased. Apparent digestibity and retention rate of energy was no significant difference between 300g/d and 450g/d concentrate level(P>0.05). Fecal energy was lowest at 300g/d concentrate level. With increasing dietary concentrate level, apparent digestibity of ADF was decreased.3.The range of pH value in the rumen fluid was 6.09～7.28. With increasing dietary concentrate level,average pH value in the rumen fluid was decreased. The range of ammonia N concentration was 20.97～32.18. As the level of dietary concentrate increased, average Ammonia N concentration and total VFA concentration in the rumen fluid was improved significantly (P<0.05), ruminal acetate,propionate and butyrate concentration were increased and the ration acetate to propionate was decreased, but there was on significant difference among each group(P>0.05).4.Based on the results of experiment , the production performance and economic benefit of Tibetan sheep under house feeding condition is best at 300g/d concentrate leve.