Effect of Different Preservation Time of Chilled Semen on the Fertility of Field Indigenous Ewes

Abstract

Background: Artificial insemination (AI), among all the fundamental systems of animal breeding, has proved to be the best and efficient method for the rapid improvement of livestock for maximum use of superior genetic merit of males on numerous dams. The frozen AI in sheep is, to date, not fulfilling the farmer’s need. Therefore, the present study aimed to determine the pregnancy rate in indigenous ewes with chilled semen preserved at different hours. Methods: Semen was collected from three indigenous rams using an artificial vagina and evaluated for its quality both in the fresh and chilled stage at 12 h, 24 h and 48 h before insemination. Trans-cervical insemination was performed in PGF2α synchronized ewes. Pregnancy was confirmed by ultrasonography at 50-60 days of gestation. Result: The motility, viability and normal sperm values of chilled semen decreased significantly (p<0.01) with increasing the duration of preservation. However, the quality of chilled semen was acceptable level for insemination. The pregnancy rate was significantly varied (p<0.01) and the higher pregnancy rate (64.28%) was achieved when AI was performed using semen stored at 4∘C for 12 h than 24 h (58.33%) and 48 h (50%), respectively. Therefore, increased the duration of preservation time of different chilling process negatively affect the semen quality and the pregnancy rates.