Effects Of Compound Feed Additives On Blood Physiological And Biochemical Indexes And Rumen Microflora Of Jersey Cattle Against Cold Stress

At present,there are many studies on stress at home and abroad,but there are few studies on anti-cold stress in ruminants.Some nutrients such as vitamins,amino acids,Chinese herbal medicines and trace elements can participate in the cold regulation of animal bodies,improve their growth performance and immune function,and reduce mortality.According to the comprehensive research from all walks of life,the research results of adding a single anti-cold stress nutritional additive to the feed are more significant,but the reports of synergistic compound nutritional additives are relatively few.Therefore,the purpose of this experiment is to study the effects of adding different additives in the diet of Jersey cows on feed intake,milk yield,apparent digestibility of nutrients,serum biochemical indexes,rumen fermentation parameters and the number and diversity of microbial flora,so as to provide practical reference for evaluating the anti-cold stress effect of different additives on dairy cows.In this experiment,30 Jersey cows with similar milk yield and consistent lactation days（160±20d）were randomly divided into 3 groups:CON group（basal diet）,HE group（basal diet+Chinese herbal extract compound 50g/head/d）and HEVY group（HE group+yeast culture 25g/head/d+50%vitamin E2g/head/d）.The experiment lasted for 60 days at an average maximum temperature of-5°C and an average minimum temperature of-15°C in the barn.Feed,feces,milk and blood samples and rumen fluid were collected regularly for measurement and statistical analysis.The results show that:1.Compared with the CON group,the feed intake of Jersey cows in the HE group and the HEVY group was significantly increased by 1.66 kg/d and 2.70 kg/d（P<0.05）,and the apparent digestibility of dietary ADF and NDF was significantly increased（P<0.05）.There was no significant difference between the HE group and the HEVY group（P>0.05）,and the milk yield of the HEVY group was significantly higher than that of the CON group and the HE group.On the 15 th day of the experiment,the milk fat rate of the HEVY group was significantly lower than that of the CON group by22.11%（P<0.05）;at 30-60 days,the lactose rate of HE group and HEVY group increased significantly by 8.86%and 7.53%compared with CON group（P<0.05）.On the 60 th day of the experiment,the SCC of HE group and HEVY group decreased significantly by 24.97%and 39.21%compared with CON group（P<0.05）,especially in HEVY group.2.Compared with CON group,the serum LDH of Jersey cows in HE group and HEVY group was significantly increased by 27.36%and 18.64%（P<0.01）.On the 15th day of the experiment,the serum Hsp-70 in HE group and HEVY group was significantly higher than that in CON group by 4.89%and 6.17%（P<0.05）;on the30 th day of the experiment,the serum Na ions in HE group and HEVY group were significantly higher than those in CON group by 34.01%and 42.83%（P<0.01）,and the serum Ca ions in HEVY group were significantly higher than those in CON group by16.22%（P<0.05）.On the 60 th day of the experiment,the serum T₃content in the HEVY group was significantly increased by 10.31%compared with the HE group（P<0.05）,and the serum T₄and GH contents in the HEVY group were significantly increased by 22.07%and 7.66%compared with the CON group（P<0.05）.3.Compared with the CON group,the s CD4 content in the serum of the HE group was significantly increased by 12.56%（P<0.05）.On the 15 th day of the experiment,the CAT content in the serum of the HE group and the HEVY group was significantly reduced by 21.68%and 18.92%（P<0.05）,and the SOD content in the serum of the HEVY group was significantly increased by 34.12%（P<0.05）;on the 30 th day of the experiment,the serum IL-1 in HE group was significantly higher than that in CON group and HEVY group by 5.12%and 11.01%（P<0.05）.On the 60 th day of the experiment,compared with the CON group,the serum TNF-αin the HE group and the HEVY group was significantly increased by 22.97%and 26.07%,respectively（P<0.01）.The serum Ig A in the HE group and the HEVY group was significantly decreased by 16.75%and 12.15%,respectively（P<0.05）.The serum MDA content in the HE group and the HEVY group was significantly decreased by 18.93%and 20.50%,respectively（P<0.05）.4.Compared with CON group,HE group and HEVY group increased the content of NH₃-N in rumen fluid of Jersey cows by 10.58%and 17.56%,respectively,but the difference was not significant（P>0.05）.The ratio of acetate to propionate in HE group was significantly higher than that in HEVY group by 52.16%（P<0.05）.The OTU number of rumen bacteria in HE group was 116 more than that in HEVY group,and the species coverage rate of rumen in three different treatment groups was more than 99%.There was no significant difference in Chao1 index,ACE index,Faith index,Shannon index and Simpson index（P>0.05）.The dominant bacteria in different treatment groups of Jersey cows were Bacteroidetes and Firmicutes,and the dominant genus was Prevotella.In summary,dietary supplementation of Chinese herbal medicine extract,yeast culture and vitamin E can improve the production performance of cold-stressed Jersey cows,increase the apparent digestibility of nutrients,enhance the immune and antioxidant capacity,enrich the rumen bacterial community structure,and have a certain alleviating effect on cold stress.