The Effects Of Active Dry Yeast On Rumen Fermentation Performance And Feed Degradation Of Qinchuan Cattle

The aim of the study was to research the effects of adding active dry yeast to diet on the feed degradation,rumen fermentation,rumen cellulolytic enzyme activity and blood biochemical index of Qinchuan cattle.Three Qinchuan cattle with permanent rumen fistula were used as experimental animal,fed with the same basal diet.The experiment consisted of three periods.Three cattle in each period were treated with three yeast supplementation levels(0,30,60g/d),and lasted 30 days then separated 5 days for adjustment.Nylon bag method were used to determine changes of dynamic degradation rate of DM,CP,NDF and ADF of four kinds of roughage(corn silage,alfalfa,wheat straw,distiller’s grains)and three kinds of protein feed(soybean meal,rapeseed meal,cottonseed meal)in the rumen,the fermentation parameters such as rumen pH,ammonia nitrogen concentration,cellulase activity and volatile fatty acids,and blood biochemical indexes.The results show that:(1)Adding active dry yeast can increase the degradation rate of DM,CP,NDF and ADF.The addition of active dry yeast could increase the rapid fermentation ratio of dry matter of different forages(corn silage,alfalfa hay,rapeseed meal)(P < 0.05)which is favorable for improving the degradation rate of rumen.The CP degradation of alfalfa,soybean meal,rapeseed meal and cottonseed meal at different time were significantly increased(P < 0.05),which is beneficial to improve the utilization efficiency of feed protein.The utilization rate of NDF and ADF of different feeds increased in different degrees,which is conducive to improve the rumen degradation rate of crude fiber.(2)The addition of active dry yeast can improve the rumen fermentation parameters.Adding active dry yeast could increase rumen pH significantly by 0.43(P < 0.05),reduce the ammonia nitrogen concentration significantly by 1.26 mg/100mL(P < 0.05),increase the concentration of total volatile fatty acids significantly by 34.27 mmol/L(P < 0.05),increase the molar ratio of acetic acid significantly by 2.88%(P< 0.05)and reduce the molality of propionic acid significantly by 2.94%(P < 0.05),then change the type of fermentation in rumen to acetic acid type.(3)The addition of active dry yeast can improve the ruminal cellulase activity.Adding of active dry yeast increases β-glucosidase,carboxymethyl cellulose enzyme and xylanase in rumen significantly by 0.13 U,0.06 U and 1.00 U respectively(P<0.05).Adding of active dry yeast increases paper filter enzymes,microcrystalline cellulase and pectinase insignificantly(P > 0.05).(4)The effect of adding active dry yeast on blood biochemical indicators is not significant.There is no significant difference in alanine aminotransferase,γ-glutamyl transpeptidase,total protein,albumin,globulin,glucose and triglyceride to add with active dry yeast respectively.There is no significant effect in body energy metabolism,lipid metabolism,immune system and so on.Aspartate aminotransferase decreased with increasing yeast addition significantly by 13.7 mmol/L(P<0.05).Urea nitrogen decreased with increasing yeast addition significantly by 0.76 mmol/L(P<0.05).It’s beneficial to improve nitrogen utilization of body.In conclusion,adding active dry yeast to diet can increase the degradation rate of cellulose in the beef cattle rumen,increase the digestibility and utilization of protein in diet,stabilize rumen pH,promote rumen fermentation and improve rumen environment.It can improve the utilization rate of digestibility and degradation of feed.