Effects Of Supplementing Betaine On Milk Performance, Serum Parameters And Hsp70Level Of Cows Under Heat Stress

This study was conducted to study the effect of feeding betaine on milk performance, serum parameters and HSP70level of cows under heat stress. The object of this study was to approach the mechanism that betaine may possibly reduce heat stress of cows. Thirty-two lactating Holstein cows were randomly divided into4treatments (8cows/treatment) according to the age, stage of lactation and milk yield:one of four supplements was blended into the TMR to produce4dietary treatments:1) control,2)10g/d of betaine,3)15g/d of betaine, and4)20g/d of betaine.. The research included three experiments.Experiment1was conducted to determine the effects of feeding betaine on milk performance of cows under heat stress. The results showed that:(1) The average temperature-humidity index (THI) was78.6units, it means the cows are suffer from moderate heat stress.(2) Supplemental betaine did not affect the body weight, rectal temperature, respiration rate and also pulse of dairy cows (P>0.05).(3) feed intake in â…¡ fed cows was significantly higher than that in control group (P<0.05); Milk yield was higher in â…¡ and â…¢ fed cows (P<0.05) compared with C and â…  fed cows; Milk lactose percentage was higher in â…¡ fed cows (P<0.05) compared with C and â…¢ fed cows, and milk lactose percentage of both â…  and â…¢ fed cows had increased (P<0.05) compared with C fed cows, but no effect of diet shown on milk fat; Milk protein percentage was higher (P<0.05) in â…¡ fed cows compared with C fed cows; No significance of somatic cell count was shown among basic diets (P>0.05), but it had decreased in treatments group than C fed cows.Experiment2was conducted to determine the effects of feeding betaine on serum parameters of cows under heat stress. The results indicated that:(1) No difference was observed in ALT or LDH activity (P>0.05) among dietary groups. CPK in group â…¢ was higher (P<0.05) than in group C, BUN, GLU, TC or TG did not differ among groups (P>0.05).(2) Total antioxidant capacity tended to increase in â… , â…¡ and â…¢ fed cows compared with C fed cows, but not significantly (P>0.05); the activity of GSH-Px was higher in â…¡ fed cows than other groups especially compared with â…¢. MDA in â…¢ fed cows was higher compared with C and â…  fed cows, but not significantly (P>0.05). Superoxide dismutase was higher (P<0.05) in â…¢ fed cows than other groups.(3) T3and T4did not differ among groups (P>0.05); Cortisol was higher in group â…¢ fed cows (P<0.05) compared with C fed cows.Experiment3was conducted to determine the effects of feeding betaine on HSP70protein and HSP70mRNA level of cows under heat stress. These findings suggest that:(1) HSP70protein did not differ among groups (P>0.05) of cows before the test, but in the end in group â…¡ was lower compared with C and â…¢ fed cows (P<0.05).(2) HSP70mRNA level of cows did not differ among groups (P>0.05) before the test, and in the end in betaine fed cows was lower compared with C fed cows, but not significantly (P>0.05).In conclusion, supplementary of betaine can improve the milk performance of cows under heat stress, and group â…¡ is better; add betaine also improved the antioxidant capacity but did not influence the physiological status of cows, and thus help the cows relief from the heat stress. Among all the treatment, treatment â…¡ showed the most effective influence and better to reduce heat stress.