Effect Of Dietary Supplementation Of Biochemical Fulvic Acid On Production Performance And Blood Indexes Of Cows During Heat Stress

Heat stress of dairy cows will greatly reduce the production performance of dairy cows,affect the health of dairy cows,and bring huge economic losses to the dairy industry.Biochemical fulvic acid(Biochemical fulvic acid,BFA)is a complex of various biologically active substances with fulvic acid as the main component,which is produced by artificially simulating natural conditions,using crop straws as raw materials and fermented by specific microorganisms.A polymer of a polyvalent phenolic aromatic compound and a nitrogen compound.As a green feed additive in livestock and poultry production,BFA has high biological functions such as ion exchange capacity,antioxidant capacity and metal chelation capacity,and can improve the growth performance and meat quality of livestock and poultry.Previous studies have shown that adding BFA to the diet can increase the feed intake,milk production and antioxidant capacity of dairy cows.Therefore,this study explored the effects of different doses of BFA in dairy cow diets on dairy cow performance,blood biochemical indicators and antioxidant capacity during heat stress,in order to provide a certain theoretical basis for the application of BFA in dairy cow production.In this experiment,40 healthy Holstein cows with consistent parity,body condition,milk production,and lactation days were selected and divided into control group and BFA supplemented group.The experimental control group was fed a basic diet(CK group);the BFA supplemented group was supplemented with biochemical fulvic acid 40 g/d,80 g/d and 120 g/d on the basis of the basic diet(respectively for the test Group I,Group II and Group III).The test time was from June to September2017,and the test period was 10 weeks,of which the pre-test period was 2 weeks and the trial period was 8 weeks.During the experiment,the physiological indexes,production performance,milk quality,blood biochemical indexes and antioxidant indexes of dairy cows were measured.By recording the temperature and humidity of the barn during the test,and calculating the THI according to the formula,it was confirmed that the cows were under heat stress during the test.The determination of physiological indicators ofdairy cows further proves that dairy cows were under heat stress during the experiment.In addition,the rectal temperature and respiratory rate of the cows gradually increaseed as the time the cow was under heat stress increases.During the test,the rectal temperature and breathing rate of the cows in each group reached38.5℃ and 80 breaths/min,respectively,indicating that the cows were in a heat stress state during the test.In the 35-56 d test,the rectal temperature and respiratory rate of the dairy cows in the test II and III groups were significantly lower than those in the CK group.Adding BFA to the diet also increases the feed intake and milk production of dairy cows,and improves milk quality.Compared with the CK group,during the test period,the feed intake of the dairy cows in the test II group and the test III group increased significantly.And during the test period,the milk production,lactose,milk fat and milk protein of the dairy cows in the test II and III groups were significantly higher than those in the CK group,while the number of somatic cells in the milk was significantly lower than that in the CK group.During the test period,the feed intake,milk production,lactose rate and non-fat solid content of the dairy cows in the test I group were not significantly different from those in the CK group.The addition of BFA in the diet also changed the blood biochemical indexes and antioxidant indexes of dairy cows.Compared with the CK group,the addition of BFA to the diet significantly reduced the content of creatinine and non-fatty acid in the blood of cows,and significantly increased the content of total protein and glucose in the blood of cows.In addition,adding BFA to the diet also significantly increased the activities of T-AOC,SOD and GSH-Px in the blood of dairy cows,and significantly reduced the content of MDA in the blood of dairy cows.In summary,feeding BFA to dairy cows can effectively alleviate heat stress of dairy cows,increase the intake and milk production of dairy cows,improve milk quality and health of dairy cows,and increase their antioxidant capacity.Therefore,BFA can be added to dairy cow diets in summer to alleviate the negative effects of heat stress,and this study recommends 80 g/d per cow.