Effect of Radix Astragali Complex Chinese Herbal Medicinal Additive on Anti-heat Stress and Mechanism in Dairy Cow

This experiment was conducted to study the effect of Radix Astragali Complex(RAC),Chinese herbal medicinal additive,on heat stressed dairy cow.12 multiparous Holstein cows,with similar parity,body weight and milk production,were allocated in a single factor design and were assigned randomly to control and treatment group,with 6 cattle per group.Cows in control group were fed basal diet,and in treatment group were fed basal diet supplemented with 200 g RAC additives.The results indicated that feed intake of treatment group was lower(P0.05) than that of control group before week 2,and gradually exceed(P0.05) the control group in week 4.Compared to control group,milk production of treatment group was higher(P0.05) from week 5 to 6.Serum T4 level and total SOD activity in treatment group were significantly higher(P0.05) than that of control group on d 40Serum GSH-Px activity in treatment group was higher than that in control group on d 20(P0.05) and d 40(P0.01),respectively.No difference(P0.05) were found on Serum GSH-Px activity between the 2 groups before d 20.Compared with control group,serum concentration of endotoxin and heat shock protein 70 in treatment group decreased by 20.53% and 6.27% on d 40,respectively,but not different(P0.05) between the 2 groups on d 40.Serum MDA level of treatment group was the same(P0.05) as that in control group before d 40,but lower(P0.05) than that in control group on d 40.Results suggested that herbal additive may increase milk yield by increasing serum T4 level and antioxidase activity,decreasing endotoxin,heat shock protein 70 and MDA level.