A Study On The Effects Of Betaine And Chromium-Yeast On Heat Stress Resistance In Cattle

Heat stress have important effects of on growth performance of animals with feed intake reduced, feed efficiency reduced, growth slowed down, and even metabolism disorder and death, which bright enormous economic losses to the animal production. There are some reports about the active effects of betaine to resist heat stress on simple stomach animal, but little on ruminant. There is little study about chromium-yeast to resist heat stress on beef cattle, although active effects have been reported on cow. For the above, there are two experiments respectively to study the effects of betaine on cow and betaine or chromium-yeast on heat stress resistance in cattle to roundly research anti-heat stress of betaine and chromium-yeast.Experiment1:An experiment was conducted using thirty-two Chinese mid-lactation Holstein cows with same parity, lactation days, day milk yield and similar weight under hot environment, dividing four groups basal with the same basal diets-TMR supplemented in random, to determine the effects of the basal diets supplemented with 0.75 g/kg,1.25 g/kg,1.75 g/kg betaine each cow on performance, biochemical and physiological parameters. The process is 50 days. The results showed 1) Betaine had no significant effect on the respiratory rate and rectal temperature (P>0.05); 2)Compared with control group, supplemental betaine had no significant effect on lactation (P>0.05),but supplement with 0.75 g/kg betaine could decreased milk protein3.34%(P＜0.05) and milk fat 18.02%(P＜0.01) respectively.3) Compared with control group, betaine had no significant effect on ALT, TP, Na+, Cl", K+,GLO, AST, T3,COR and insulin (P>0.05),but supplement with 0.75 g/kg and1.25 g/kg betaine made the content of serum T4 respectively decreased by 25.78%(P＜0.01) and 30.08%(P＜0.01) respectively.4) Supplemental betaine had no significant effect on GSH-Px, HSP, SOD and MDA (P>0.05).Experiment2:Purpose of this experiment was to study the effect of betaine and yeast chromium on production performance and physiological and biochemical indexes of beef cattle under heat stress.32 with similar initial weight of the Chinese Simmental cattle were randomly divided into 4 groups. Control group was fed the basal diet. 1.0g/kg betaine,0.8 mg/kg chromium-yeast, mixture of 1.0 g/kg betaine and 0.8 mg/kg chromium-yeast was respectively added into the basic diet. Experimental period was 42 days. The results show that: (1) Betaine or chromium-yeast have no evidently effect on respiratory rate and rectal temperature of beef cattle (P>0.05); (2) Compared with the control group, the average feed intake of cattle in group betaine and betaine-chromium-yeast respectively raised by 17.22%, 4.38%, group chromium-yeast decreased by 1.81%, but all not significantly (P>0.05); daily gain of betaine group, chromium-yeast group and betaine-chromium-yeast group respectively raised by 39.66%,31.03% and 8.93%,but all not significantly (P>0.05); meat feed ratio of group betaine, chromium-yeast and betaine-chromium-yeast respectively decreased by 16.04%,25.07%(P<0.05) and 0.79%. (3) Betaine can make the level of blood HSP-70 decreased(P<0.05), while TC increased(P<0.05).Yeast-chromium and mixture of yeast-chromium and betaine can also make HSP-70 levels of blood decreased, and TC increased, but both did not reach significant level (P>0.05). Yeast-chromium could make significant urea level of blood raised (P<0.05).In summary, although betaine could bright level of serum T4 of cow down under heat stress to some extent, but overall heat stress could not be relieved by additive of betaine. Betaine and chromium-yeast both had no significant effect on rectal temperature and respiratory rate of beef cattle under heat stress, but they were able to improve the daily gain and feed conversion efficiency of beef cattle under heat stress to some extent, and chromium-yeast could significantly improve the feed conversion efficiency. Chromium-yeast and betaine both could bright down the level of serum HSP-70, and could partially alleviate heat stress of beef cattle. Betaine has some active effect on the beef, but no obvious effect on the cow. Chromium-yeast could significantly alleviate the heat stress of beef cattle. Mixture of betaine add chromium-yeast might enhance the heat stress. The mechanism need further invesigations.