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. |