The Variations of Hormone Levels During the Estrous Cycle in Qinchuan Cattle and Parity Differences
Low reproductive efficiency in beef cattle remains a critical factor limiting the industry's develop-ment.Although the use of exogenous reproductive hormones can regulate the estrous cycle and improve fertility,the differences in the hormonal response between the cows with different parities during estrous regulation and superovu-lation have been observed.In this study,we employed the ELISA method to measure hormone levels,monitoring the concentrations of follicle-stimulating hormone(FSH),luteinizing hormone(LH),estradiol(E2),and pro-gesterone(P4)in QinChuan cows throughout their estrous cycles.The results showed that the FSH concentration in young cows on day 15 was significantly higher than that in multiparous cows(P＜0.05).Similarly,the E2 con-centration was significantly higher in young cows on days 0 and 20(P＜0.05),while the P4 concentration was sig-nificantly elevated in young cows on days 5,10,15,and 20(P＜0.05).Furthermore,LH concentration was con-sistently higher in young cows throughout the entire estrous cycle(P＜0.05).These findings provide a basis for developing parity-based hormone treatment strategies,thereby improving reproductive efficiency in beef cattle.
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