Effect of injection of GnRH and hCG on day 5 post mating on maternal P4 concentration and reproductive performance in Afshari ewes

Embryonic mortality is a common cause of economic loss in sheep. Insufficient luteal function and low concentration of maternal progesterone is one of the major reasons of this mortality. This study was conducted to investigate the effects of GnRH and hCG administration on day 5 after mating on reproductive performance in ewes. Total of 60 synchronized ewes were mated with fertile rams and equally were assigned to four groups. Ewes in GnRH, hCG and hCGᩴ groups (n=15/group) received an i.m. injection of 25 μg GnRH analogue, 400 IU hCG and 25 μg GnRH analogue 400 IU hCG on day 5 post-mating, respectively. The ewes in the control group (n=15) did not receive any treatment. Blood samples were collected on days 7, 12, 17 and 22 post-mating. Plasma P4 concentrations were higher at days 12 and 17 and 22 postmating in GnRH, hCG and hCGᩴ treated ewes than those of control ewes (P