Effect of exogenous insulin administration on ovarian function, embryo/fetal development during pregnancy in goats

Abstract

The effect of insulin was investigated on ovarian follicle population, ovulation rate, hormonal profiles and embryo/fetal development during pregnancy using transrectal ultrasonography in goats. Twelve goats synchronized in estrus were selected for the experiment. They were divided into two groups, viz. (untreated control, n = 6) and (insulin treated, n = 6). In treated group long acting bovine insulin was administered @ 0.2 IU/kg body weight subcutaneously for three consecutive days, i.e. days 7–9 of estrous cycle. Thereafter, weekly single injection of insulin was continued for rest of the experiment. However, in control group only normal saline was injected as placebo. Breeding was allowed by natural service in both the groups. The does were subjected to B-mode transrectal ultrasound scanning of ovary and uterus weekly up to 120 and 98 days of gestation, respectively. Blood samples were collected weekly up to 135 days of gestation for the estimation of estradiol 17β and progesterone (P4). The result revealed no difference in mean number of total follicles between the control and insulin treated groups. The diameter of medium follicle did not differ where as diameter of large follicle was comparatively higher in treated than control goats. The average number of corpus luteum (CL) was higher in insulin treated group as compared to control (1.66 vs. 1.16). However, the number as well as mean diameter of CL did not differ significantly between treated and control group. Serum concentrations of estradiol 17β and progesterone were significantly ( P < 0.01) higher in treated than control goats. Embryonic vesicle was detected by day 21 in both the groups, however, its diameter did not differ significantly (0.73 and 0.72 cm) between the groups. The twinning percentage was higher (50 vs. 16%) in insulin treated than the control goats. Placentome diameter was also higher ( P > 0.05) in treated animals. The results demonstrated beneficial effect of exogenous administration of insulin on ovarian function and twinning percentage in goats.