Effects Of Grazing Regime On Feed Intake And Apparent Digestibility Of Yak And Tibetan Sheep

Bos grunniens and Ovis Aries are the two most important grazing animals unique to the Tibetan plateau.Grazing is the most economical and effective way to use the alpine grassland in the Qinghai-Tibet plateau.The knowledge of forage intake of livestock and apparent digestibility of livestock to pasture is critical for determining yak and Tibetan sheep grazing regimes(Yak grazing alone,Tibetan sheep grazing alone,yak and Tibetan sheep mixed grazing in different proportions)on the Tibetan Plateau.To explore the effect of grazing regimes(Yak grazing,YG,Sheep grazing,SG,Mixedlivestock grazing with ratios of yak to Tibetan sheep as1:2,MG 1:2,(Mixed-livestock grazing with ratios of yak to Tibetan sheep as1:4,MG 1:4,Mixed-livestock grazing with ratios of yak to Tibetan sheep as1:6,MG 1:6))and a control trial on forage intake of livestock and apparent digestibility of livestock to pasture by measuring the endogenous indicators(4-n acid insoluble ash)and the conventional nutrients in the forage and faeces of yak and Tibetan sheep,a manipulated grazing experiment was conducted on an alpine grassland in the Qinghai Lake basin.And to study the effects of grazing mode on food intake and apparent digestibility of yak and Tibetan sheep,and to provide basic data for scientific management and rational utilization of alpine grassland.The results showed that:1.Mixed grazing can promote the food intake of yak and Tibetan sheep: in summer,autumn and winter,the food intake of yak and Tibetan sheep is the lowest under single grazing.Yaks had higher food intake at MG 1:6mg 1:2 and MG 1:4.The intake of Tibetan sheep was the highest at MG 1:2.2.Validation fecal nitrogen index method is used to determine each season grazing the applicability of the yak and Tibetan sheep intake: Lukas fecal nitrogen index method 2 is used in the summer(a2 = 0.7976)than manure nitrogen index method 1(a1 = 0.7286)to predict grazing feed intake of high accuracy,in the autumn and winter use Lukas fecal nitrogen index method 1(a1 = 0.7286)predicts grazing feed intake is relatively accurate,in the autumn cheng-jie wang fecal nitrogen index method is used to predict Tibetan sheep grazing feed intake is relatively accurate,in the summer and winter cheng-jie wang fecal nitrogen index method is used to predict Tibetan sheep grazing feed intake of low accuracy.3.Mixed grazing can promote the forage intake of yaks and Tibetan sheep with higher nutrition: the forage intake of yaks and Tibetan sheep with higher nutrition and the daily intake of each nutrient at MG 1:2 and MG 1:6.4.Mixed grazing can promote the apparent digestibility of yaks and Tibetan sheep to herbage: the digestibility of yaks under MG 1:6 to forage nutrients is higher in winter,the digestibility of Tibetan sheep under MG 1:6 to forage nutrients is higher in summer,and the digestibility of Tibetan sheep under MG 1:6 to forage nutrients is higher in autumn.In conclusion,mixed grazing can improve the food intake of yaks and Tibetan sheep,promote the intake of higher nutritive herbage and apparent digestibility of nutritive herbage by yaks and Tibetan sheep.Considering the feed intake of grazing livestock,it is reasonable for yak to use MG 1:4 to graze Tibetan sheep and MG 1:2 to graze them.Considering the forage nutrition,it is reasonable for yak to graze Tibetan sheep at MG 1:2 and MG 1:6.Considering the apparent digestibility of livestock to forage,it is reasonable to use MG 1:4 and MG 1:6 for yak and MG 1:2 for Tibetan sheep.Considering the forage intake of yaks and Tibetan sheep,forage nutrient and the apparent digestibility of herbage under different grazing modes,the researcher suggested that the grazing mode of MG1:2 and MG 1:6 should be adopted.