Study On Behavior,Physiology And Molecular Mechanism Of Postpartum Estrus In Small Tail Han Sheep

The purpose of this paper is to study the distribution of daily behavior,the secretion of major reproductive hormones and the expression of hormone receptors in Small-tailed Han sheep at different intervals from delivery to first estrus.In this study,11 20-month-old pregnant ewes were selected as the research object.The time interval from delivery to first estrus was divided into five parts:the early stage after delivery,the middle and early stage after delivery,the middle stage after delivery,the middle and late stage after delivery,and the late stage after delivery.Ten ewes had different intervals from delivery to first estrus.Ten ewes were divided into two groups Ⅰ(44 ± 6 days)and Ⅱ(64 ± 6 days)according to the length of the interval.Then,the daily behavior of ewes in the two groups,including standing,moving,feeding,exploring,lying,ruminating and watching,was observed by scanning sampling observation method.The results showed that in the interval from the time of delivery to the first estrus,the ewes in group Ⅰ had the most rest and standing,and the ewes in group Ⅱhad the most rest and intake;the feeding of the ewes in both groups increased first and then decreased.But in the final stage of the observation period(group Ⅰ 22～30d,group Ⅱ 42-50d),the feeding of group Ⅰ ewes increased,while the group Ⅱ ewes decreased;within the first 30 days after childbirth,the standing of ewes in group Ⅰ was generally higher than that of ewes in group Ⅱ,and the difference was significant at the 6th and 10th days(P<0.05).The exploring of ewes in group Ⅰ were generally more common than the ewes in group Ⅱ,and the difference was significant at the 10th day after childbirth(P<0.05);The change trend of exploring and feeding of ewes in groupⅠ was consistent,but that of ewes in group Ⅱ was just the opposite.Secondly,the levels of FSH,LH,E2,P4 and MLT hormones in feces were detected by ELISA.It was found that the reproductive hormone MLT in feces of ewes in group Ⅰ was lower than that of ewes in group Ⅱ in the first 30 days after delivery or in the five stages of interval time,and the difference was significant at the 10th,22nd and 30th days after delivery(P<0.05).Finally,after estrus identification,the ewes were slaughtered and ovarian tissues were taken.The expression of FSHR,LHR,ESR1 and PGR genes was detected by Q-PCR.The results showed that in the first estrus period after delivery,the expression of FSHR and LHR genes of ewes in group Ⅰ was higher than that of ewes in group Ⅱ,and the expression of ESR1 and PGR genes were lower than those of ewes in group Ⅱ,but the difference was not significant(P>0.05).In summary,the behavioral performance of the ewes MLT secretion level of ewes in group Ⅰ may contribute to their early estrus,while the ewes in group Ⅱ have relatively late estrus.