Effect of defined-time artificial insemination following estrus synchronization on conception rate in cashmere goats
To compare the conception rate of defined-time artificial insemination with frozen-thawed semen following estrus synchronization in autumn in cashmere goats and define the optimal insemination time to achieve a higher conception rate,the progesterone suppository,pregnant horse serum gonadotropin(PMSG)and PGF2α were used to induce estrus and ovulation in Liaoning cashmere goats in this experinent.The does were divided into 1 control group and 4 experimental groups,which inseminated with 0.25 mL semen at 0 h,6 h,12 h,18 h and 24 h following the onset of estrus through estrus synchronization,respectively.The results showed that the estrus rates were 86.67%in the control group and 83.33%,90.00%,86.67%and 83.33%in the four experimental groups,respectively.The conception rates were 15.38%in the control group,and 56.00%,57.89%,36.00%and 4.76%in the four experimental groups,respectively,with suggesting that the optimal insemination time could be at 6-18 h following the onset of estrus.In the screening test,the does following the onset of estrus used as the control group(at 6 h)and four experimental groups(at 9 h,12 h,15 h and 18 h)for frozen semen insemination.The results showed that no significant difference in estrus rate among the control group and four experimental groups was found(P>0.05),and the conception rate was 59.25%,66.67%,57.69%,44.44%and 32.00%in the control group and in four experimental groups,respectively,suggesting that the optimal time for frozen semen insemination could be at 9 h following the onset of estrus through estrus synchronization.
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