Effect Of Rice Straw Steam On Rumen Fermentation In Vitro And Nutrient Disappearance Rate Of Yanbian Yellow Cattle

As an important energy source,biomass energy has always been favored by researchers at home and abroad,and is likely to become an important role in the sustainable energy group in the future.As one of the biomass energy,the annual output of crop straw is very rich in our country which can reach hundreds of millions.However,its comprehensive utilization rate is not proportional to its yield.in many applications of straw processing,feed utilization has always been the mainstream.In this paper,the effects of different steam time on rumen fermentation and nutrient disappearance rate of rumen were studied,so as to provide reference for the application of straw as feed in ruminants.In this experiment,rice straw was cut into small sections and cooked in a steamer.After different steam time,samples were taken for two experim ents.Two healthy Yanbian yellow cattle with rumen fistula were selected.Sufficient rumen fluid was collected before morning feeding,put in a culture bottle and divided into control group(untreated)and experim ental group 1(steam treatment 30min)according to the steam time of rice straw added in the substrate.Test group 2(steam treatment 40min),experiment group 3(steam treatment 50min),experiment group 4(steam treatment 60min),each group had 3 repeats.At 0h,4h,8h,12h,48h,the rumen pH,NH3-N concentration,total VFA,acetic acid concentration,propionic acid concentration and butyric acid concentration were measured.At the same time,weigh the sample,put it in a nylon bag,tie it and weigh it.Twelve nylon bags divided into 4 time points were put into the fermentor at one time,and 3 parallel samples were tied together with nylon rope at each time point,and put into the rumen in vitro simulation device with automatic rotation at 39 ℃ to simulate the rumen environment and peristalsis process.Three nylon bags were taken from each tank at 24 h and 48 h respectively,and the disappearance rate of DM,NDF and ADF of acid detergent fiber were measured.The results showed that in the experiment of the effect of rice straw steam time on rumen environment the rumen pH of 50min was significantly decreased(P<0.05),the concentrations of acetic acid and propionic acid in rumen fluid were significantly increased(P<0.05),and the contents of total volatile fatty acids in rumen fluid of 40min and 50min were significantly increased(P<0.05).In the experiment of the effect of rice straw staem time on Rumen in vitro disappearance rate,the dry matter loss rate of 50 min and 60 min steam treatment was significantly increased(P<0.05),the disappearance rate of neutral detergent fiber in 60 min steam treatment was significantly increased(P<0.05),and the acid detergent fiber loss rate of 50 min steam treatment was significantly increased(P<0.05).In summary,combined with the above two experiments it is concluded that the steam time of 50min is more appropriate,which can not only improve the rumen environment,but also promote rumen digestibility.