Influence of clomiphene citrate on induced ovarian hyperstimulation and subsequent fertility in Damascus goats

Abstract

Efficiency of substituting conventional gonadotropin-based superovulation with a clomiphene-based regimen in goats was investigated. Forty pluriparous Damascus does were synchronized for estrus by double doses of PGF2α, 125 μg each, 10 days apart and were randomly divided into 3 groups. The first group served as control (n = 12), whereas superovulation was induced in the second group (n = 14) by 600 mg oral administration of clomiphene. The third group (n = 14) received 600 i.u eCG intramuscularly. Both superovulation treatments were delivered in serial equal doses over 3 consecutive days. Ovarian follicular activity was daily monitored by trans-rectal ultrasonography until the follicle(s) reached the pre-ovulatory phase (Ø ≥ 5 mm), where ovulation was promoted by 20 μg GnRH i.m. Estrus occurrence was observed, and does that exhibited estrus were naturally mated soon after GnRH treatment and 24 h later. The changes in reproductive hormones, blood metabolites and enzymatic activities were also monitored alongside ovarian ultrasonography. Ultrasound examination was conducted 72 h after GnRH treatment to confirm ovulation, as well at day 35 post mating for early pregnancy diagnosis. Reproductive performance indices; i.e. estrus response, ovulation rate, conception rate, kidding rate, litter size and sex ratio were also showed. The results recorded 100% estrus response in all goat groups. The highest (P < 0.05) ovarian activity was observed in both superovulated groups at T96, along with increased estradiol levels, compared to those of control. Only blood glucose and total cholesterol levels were affected (P < 0.05) by ovarian dynamics and estrus activities. Additionally, clomiphene-treated goats recorded the highest (P < 0.05) conception rate (100%) and litter size (1.85) compared to eCG-treated and control goats. None of the delivered kids recorded postnatal mortality during the first week post-partum reflecting normal health status. These results point to efficient utilization of clomiphene as a reliable substitute to traditional superovulation in goat genetic improvement programs.