关键词: 驴;诱导发情;前列腺素F2α;孕马血清促性腺激素;人绒毛膜促性腺激素;受胎率;非繁殖季节

Abstract: [Objective]To assess the effect of PGF2α, PMSG and hCG with different treatment protocols on follicular growth, ovulation rate, estrus rate, conception rate and pregnancy rate of female donkeys selected from Tongliao region of Inner Mongolia during the seasonal anestrus. [Methods] A total of fifty healthy female donkeys 2-6 years of age in seasonal anestrus were randomly divided into four groups （A, B, C and D）. A hormone-induced estrus experiment with administration of PGF2α in combination with PMSG was carried out： the donkeys in groups of A, B and C were injected with 2 mL PGF2α for five consecutive days; those in group A or group B were subsequently administrated with 1 000 IU or 500 IU PMSG at the sixth day, respectively; group C received no PMSG treatment. After the hormone-induced estrus, the group A and group B were randomly allocated to groups of A1, A2 and groups of B1, B2, respectively, to perform the ovulation induction experiment： the donkeys in groups of A1, B1 and C received hCG injection （total dosage 1 500 I U） when their follicular diameters were larger than 35 mm; those in groups of A2 and B2 received no hCG treatment, and their follicles naturally developed until ovulation. The donkeys exhibiting estrous appearance were subjected to natural mating. Meanwhile, the ovarian development of the donkeys was monitored by using rectal examination and B-type ultrasound examination during the experimental period. Group D served as a control of non-hormone treatment. EResultslThe estrus rate of group C was 30% and the ovarian corpus luteum was completely regressed at the fifth day of PGF2α treatment; while there was no obvious difference in estrus rate between group A （93.33% ） and group B （86.66%）, both of them were obviously higher than group C. The ovulation rate of groups of A1, B1, A2 and B2 was 100%, 77.78%, 60.00% and 50.00%, respectively. The highest conception rate （88.89%） and pregnancy rate （80.00%） were both observed in group A1 followed by group B1（66.67% and 60.00%, respectively）. Groups of B2 and C had lower conception rate and pregnancy rate. While there was one donkey had estrous appearance in group D, no pregnancy was observed after mating. [Conclusion]Although single treatment of PGF2α had no obvious estrus-inducing effect on female donkey during non-breeding season, it had obvious effect on corpus luteum regression; the combinative treatment of PGF2α and PMSG showed satisfied estrus-inducing effect. After estrus induced by PGF2α in combination with PMSG, injection of hCG accelerated the ovulation of the dominant follicles in ovary of the female donkeys and thus elevated the ovulation rate. The optimized treatment protocol of hormone-induced estrus and ovulation for female donkey during non-breeding season was as follows： （1） injection of 2 mL PGF2α for five consecutive days, （2） administration of 500 IU PMSG at the sixth day, （3） injection of 1 500 IU hCG when the diameter of dominant follicles reached 35 mm,（4） natural mating after ovulation.