Effect Of Feeding Yeast Culture On Milking Performance,Serum And Rumen Fermentation Index Of Dairy Cows

In order to explore the effects of feeding different yeast cultures on the milking performance,serum biochemical indexes and rumen fermentation indexes of dairy cows at the early stage of lactation,45Holstein cows with lactation days of 20±3 days and parity 3.20±0.84 were selected,15 cows per group to ensure that there is no significant difference in parity and milk volume at the beginning of the experiment（P>0.05）.No yeast culture products were added to the diet of the control group.The test group I was fed with No.1 yeast culture（YC-1）at 30 g/d per head,and the test group II was fed with No.2 yeast culture（YC-2）at 30 g/d each.The pre-trial period is 7 days,and the trial period is 90 days.The test cows were fed with an automatic trough feeding system,and the feed intake of each cow was recorded.Record the milk volume of each cow per shift,and measure the milk composition,serum biochemical indicators and rumen fermentation indicators every 15 days.The effect of feeding different yeast cultures on DMI,milk yield and milk composition:Compared with the control group,the DMI of the test group I increased by 0.55 kg/d,and the DMI of the test group II increased by 0.82 kg/d,but the difference was not significant（P>0.05）;The milk fat production of test group II was significantly higher than that of the control group（P<0.05）;the 4%FCM of test group I increased by 0.79 kg/d compared with the control group,and the 4%FCM of test group II increased by1.26 kg/d d,but the difference was not significant（P>0.05）.The apparent digestibility of DM in the test group II was significantly higher than that of the control group and the test group I（P<0.05）.The apparent digestibility of CP,the apparent digestibility of NDF and the digestibility of ADF in the test group II were significantly higher than those of the control group（P<0.05）.Feeding YC-2 can increase the apparent digestibility of DM,CP,NDF and ADF;increase milk fat production and milk production;feeding YC-1 can increase milk production.Feeding YC can reduce SCC in milk.Effects on serum biochemical indicators:The BUN concentration of test group I and test group II were significantly higher than that of the control group（P<0.05）;the ALB content of test group II was significantly higher than that of the control group（P<0.05）.The GSH-Px activity of test group I and test groupⅡincreased by 0.67μmol/L（P=0.09）and 0.73μmol/L（P=0.07）,respectively,and both have a rising trend（0.05≤P<0.10）.Feeding YC can increase the degradable protein in the rumen of dairy cows,which has a positive effect on improving the antioxidant performance of dairy cows;it has no significant effect on the liver function of dairy cows.Feeding YC-2 can increase the protein intake of dairy cows.Effect on the rumen fermentation indexes of dairy cows:the concentration of NH₃-N in the test group II decreased by 3.89 mg/d L（P=0.09）,compared with the control group（0.05≤P<0.10）;the acetic acid in the test group II The concentrations of propionic acid and TVFA were significantly higher than those of the control group and the test group I（P<0.05）.The butyric acid concentration of the test group II increased by 0.98 mmol/L（P=0.09）compared with the control group.There is a rising trend（0.05≤P<0.10）;the ratio of acetic acid/propionic acid in the test group II was significantly lower than that of the control group（P<0.05）,and the ratio of acetic acid/propionic acid in the test group I was lower than the control group by 0.13（P=0.07）Compared with the control group,there is a decreasing trend（0.05≤P<0.10）.Feeding YC can increase milk yield,has a positive effect on improving antioxidant performance and improving rumen fermentation,and YC-2 feeding effect is better.