Effect Of Lonicera Japonica Extract On Lactation Performance,Antioxidant Status And Rumen Microbial Flora Structure In Heat-stressed Dairy Cows

The objective of the present study was to evaluate the effects of Lonicera japonica extract（LJE）on lactation performance,serum biochemical and hormone indices,antioxidant status,immune function and rumen microorganisms in heat-stressed dairy cows,which might provide a theoretical basis for the application of LJE in heat-stressed dairy cows.The specific contents are as follows:Experiment 1:The objective of this study was to investigate different doses of LJE on lactation performance,antioxidant status and immune function of heat-stressed dairy cows,and to explore the optimum amount of LJE to effectively alleviate heat stress in dairy cows.Twenty-four healthy Chinese Holstein dairy cows with similar milk yield,parity and days in milk were randomly assigned to 4 groups with 6 cows per group:a negative control group（without LJE supplementation;CON）and groups that received LJE at 14,28,and 56 g/d.The results showedas follows:1)Dietary supplementation with LJE significantly decreased the rectal temperature of heat-stressed dairy cows（P<0.05）,but didi not affect respiratory rate（P>0.05）.2)Dietary supplementation with LJE had no significant effects on lactation performance of heat-stressed dairy cows（P>0.05）.3)Dietary addition of LJE significantly decreased the serum creatinine content of heat-stressed dairy cows（P<0.05）.4)Dietary supplementation with LJE significantly increased the T₃ concontrations,and quadratically increased the T₄ in serum（P<0.05）.5)Supplementation with LJE enhanced the activity of T-AOC and SOD,and quadratically increased the activity of GSH-Px in serum,but decreased the concentration of MDA（P>0.05）.6)The concentrations of immunoglobulin G and interleukin-4 in serum of heat-stressed dairy cows from LJE-28 group were significantly higher than those in the CON group,but that of IL-2 decreased（P<0.05）.Dietary supplementation with LJE tended to reduce the serum heat shock protein-72 content of heat-stressed dairy cows（P=0.06）.Under the conditions of the present study,the optimal amount of supplemented LJE is 28 g/d.Experiment 2:The objective of this study was to investigate the effects of adding 28 g/d LJE on lactation performance,serum hormone indices and immune function of heat-stressed dairy cows.Twelve healthy Chinese Holstein dairy cows with similar milk yield,parity and days in milk were randomly assigned to 2 groups with 6 cows per group.Cows in CON group were fed a basal diet,and cows in LJE group were fed the basal diet supplemented with 28 g/d LJE.The results showed as follows:1)Dietary supplementation with 28 g/d LJE significantly reduced rectal temperature in heat-stressed cows（P<0.05）,but had no significant effect on respiratory rate（P>0.05）.2)Dietary supplementation with 28 g/d LJE did not affect lactation performance of heat-stressed dairy cows（P>0.05）.3)The addition of 28 g/d LJE significantly reduced the serum creatinine content of heat-stressed cows（P<0.05）,but increased the serum glucose content of heat-stressed dairy cows（P<0.05）.4)The addition of28 g/d LJE increased the T₃ and glucagon contents of heat-stressed dairy cows（P<0.05）.5)The addition of 28 g/d LJE significantly increased the IgG concentration（P<0.05）,but decreased the HSP-72 content in the serum of heat-stressed dairy cows（P<0.05）.In summary,LJE can alleviate heat stress in dairy cows by improving heat stress cow rectal temperature,immune response,antioxidant properties and endocrine activity.Experiment 3:The objective of this study was to investigate the effects of adding 28 g/d LJE on rumen fermentation parameters and rumen microorganisms of heat-stressed dairy cows.The experimental design is the same as Experiment 2.The results showed as follows:1)Dietary supplementation with 28 g/d LJE significantly reduce the rumen pH of heat-stressed dairy cows（P<0.05）and increase the concentration of acetic acid in the rumen（P<0.05）and tended to increase that of the isovaleric acid（P=0.07）in heat-stressed dairy cows.2)The addition of 28 g/d LJE significantly increased the relative abundance of Elusimicrobia,Unclassified＿Prevotellaceae,Cupriavidus,and Selenomonas in the rumen of heat-stressed dairy cows（P<0.05）.3)The addition of 28 g/d LJE had no significant effect onthe diversity and abundance of rumen Archaea（P>0.05）.In summary,LJE,to some extent,improved rumen microbial community and promoted rumen fermentation.