Effects of Melatonin on Estrus Synchronization and Conception Rate in Beef Cattle
The aim of this study was to investigate the metabolism of melatonin(MT)in beef cattle and the effects of MT on the synchronous estrus rate,conception,blood antioxidant level and reproductive hormones.In this study,firstly,twelve beef cattle were randomly divided into four groups,0 mg,0.464 mg,4.64 mg and 46.4 mg melatonin were injected at 8 o'clock in the morning and the melatonin concentra-tions at different time pionts were measured.Then,eighty beef cattle were randomly divided into four groups,melatonin of 0 mg,0.464 mg,4.64 mg or 46.4 mg was injected during the second injection of clo-prostenol sodium and artificial insemination in the treatment,and estrus rate and estrus conception rate were counted.The blood was collected for the determination of plasma antioxidant level and reproductive hormone content.Results showed that after different doses of melatonin injected subcutaneously,plasma melatonin was at a high value and significantly higher than the control group at 0.5 h(P＜0.01),then it begen to decline.0.464 mg melatonin injected subcutaneously into beef cattle was metabolized to the nor-mal level through 8 h,while 4.64 mg or 46.4 mg melatonin to the normal level through 14 h.When me-latonin was injected subcutaneously during estrus synchronization,46.4 mg melatonin injected subcutane-ously could significantly improve the estrus rate of beef cattle(P＜0.05),and the conception was higher than that of the control group.4.64 mg or 46.4 mg melatonin could significantly reduce the content of MDA(P＜0.05),increase the content of GSH-PX(P＜0.05),and significantly increase the content of SOD(P＜0.01).46.4 mg melatonin could significantly increase the concentration of FSH and LH in plas-ma during mating(P＜0.05).4.64 mg melatonin could significantly increase the concentration of FSH and E2 during mating(P＜0.05),and can increase the P4 content on the 7th day after insemination(P＜0.05).This study shows that exogenous melatonin can enhance the synchronous estrus rate and conception in two cloprostenol sodium treatments by improving antioxidant level and reproductive hormone concentration of beef cattle,and the effect is best when 46.4mg melatonin is injected subcutaneously into beef cattle.
万方数据
维普
