Effects Of Astragalus Polysaccharide On Performance,serum Biochemical Indices And Gastrointestinal Microflora Of Dairy Cows

This experiment was conducted to investigate the effects of Astragalus polysaccharides on performance,milk quality,serum biochemical indices,rumen fermentation,nutrient apparent digestibility and gastrointestinal microflora of dairy cows.Forty-four healthy Chinese Holstein dairy cows with similar body weight（600±50.00 kg）,lactation days（40±15 d）,parity（2.70±0.93 fetuses）and similar lactation production were randomly divided into four groups:CK group,APS20 group,APS55group and APS90 group.All experimental cows were fed the basic diet.On the basis,the experimental groups was gavaged 20 g,55 g and 90 g APS solution 200 m L per day,respectively,for 70days（pre-feeding period of 10 days,and positive feeding period of 60 days）.Effects of APS administration on milk yield,milk composition,somatic cell score and flavor substances in milk:there were no significant differences in milk yield and milk composition between experimental group and CK group（P>0.05）.During the whole experiment period,the somatic cell score in APS55 group was significantly higher than that in CK group（P<0.05）.The contents of volatile organic compounds of flavor substances alcohols,acids and hydrocarbons in the milk of the experimental group was extremely significantly higher than that of the CK group（P<0.01）.These results suggest that administration of APS can increase the content of lipid-flavored flavor substances in milk and reduce the number of cells in the milk,and the effect is better in APS55 group.Effects of APS administration on serum biochemical indices of dairy cows:During the whole experiment period,the serum IL-2 content in APS55 group was extremely significantly higher than that in CK group（P<0.01）;On day 60,the IL-6 content in APS55 group was significantly higher than that in CK group（P<0.05）;In the whole experiment period,the CAT concentration in experimental group was extremely significantly higher than that in CK group（P<0.01）;On day 60,compared with CK group,GSH-Px concentration in APS20 group,APS55 group and APS90 group was significantly increased（P<0.05）,and T-AOC concentration in APS55 and APS90 groups was extremely significantly increased（P<0.01）;On day 60,the CREA content in APS55 group was significantly lower than that in CK group（P<0.05）.These results suggest that APS can improve immune function and antioxidant function,improve lipid metabolism and promote protein deposition of dairy cows,but have no significant effect on liver and kidney function,and the effect of APS55 group is better.Effects of APS administration on rumen fermentation and nutrient apparent digestibility of Dairy Cows:The acetic acid concentration in APS55 group was significantly higher than that in CK group（P<0.05）;The concentrations of propionic acid and butyric acid in APS55 group were extremely significantly higher than those in CK group（P<0.01）;The NH₃-N concentration in APS55 group was significantly higher than that in APS90 group（P<0.05）,The MCP content in APS55 group was extremely significantly higher than that in APS90 group（P<0.01）.Compared with CK group,DM digestibility in APS55 group was significantly increased（P<0.05）;The Ash digestibility in APS55 group was extremely significantly higher than that in CK group（P<0.01）.These results suggest that APS administration can promote rumen fermentation,improve rumen fermentation pattern,change the concentration of NH₃-N and VFA,and improve nutrient digestibility,and APS55 group has a better effect.Effects of APS administration on gastrointestinal microflora of dairy cows:at the level of phylum,in rumen,Firmicutes in APS55 group was extremely significantly higher than CK group（P<0.01）;The intestinal Firmicutes level in APS55 group was extremely significantly higher than that in CK group（P<0.01）.At the rumen level,compared with CK group,the Prevotellaceae YAB2003 group level in experimental group was significantly decreased（P<0.05）,the Lachnospiraceae NK3A20 group level in APS55 group was significantly increased（P<0.05）,and the Prevotellaceae UCG-004 level in APS55group was significantly increased（P<0.05）.In intestinal tract,compared with CK group,prevotella level in APS55 group was significantly decreased（P<0.05）,and the Lachnospiraceae NK3A20 group in APS55 group was extremely significantly increased（P<0.01）.The Succiniclasticum level in APS55group was extremely significantly increased（P<0.01）.These results suggest that oral administration of APS can stabilize the rumen environment,increase the relative abundance of cellulose-degrading bacteria in the rumen,maintain intestinal health,and regulate the relative abundance of bacteria related to intestinal inflammation,and the effect of APS55 group is better.In conclusion,in this experiment,APS administration of 55 g/d can effectively improve milk quality,promote lipid metabolism and protein deposition,improve immune and antioxidant capacity,improve rumen fermentation,improve nutrient digestion ability,and increase the richness and diversity of bacteria in gastrointestinal tract of dairy cows.Increase the relative abundance of cellulose-degrading bacteria in the rumen,maintain intestinal health,and regulate the relative abundance of bacteria related to intestinal inflammation.