Effect of Short-Term Glycerin Supplementation on Follicle Dynamics and Pregnancy Rate in Goats

Abstract

We investigated the effects of short-term glycerin supplementation on follicular dynamics and pregnancy rates. Twenty-five goats with synchronized estrus and follicular waves with three injections of a prostaglandin analog every 7 days were used. Two days after the second injection, 13 goats were randomly chosen to receive an oral drench of 200 mL of glycerin (glycerin group [GG], n = 13) for 6 days, whereas the remaining 12 animals received an oral drench of saline (control group [CG], n = 12). At 24 and 48 h after the third injection, the goats mated. The animals were kept in a collective stall and received the same diet. The GG had higher blood glucose levels during the supplementation period than the CG (76.4 ± 1.9 vs. 50.3 ± 0.7 mg/dL; p < 0.01). The glycemic peak was recorded 4 h after the glycerin administration (102.3 ± 5.1 mg/dL) and remained higher than that in the CG 8 and 12 h later. The GG goats had a higher rectal temperature, heart rate, and respiratory rate than the CG goats and showed an increase in these parameters 4, 8, and 12 h after glycerin drenching. The GG animals also exhibited increased stress, urination, and drinking behaviors and reduced rumination. The ultrasonographic analysis showed a higher number of follicles with a diameter >4 mm (p < 0.05) and a greater follicular diameter (p < 0.01) in the waves before and after ovulation induction. The pregnancy and twinning rates and litter size at parturition were not different between the groups. Short-term supplementation with glycerin positively affects ovarian stimulation but has no effect on the reproductive response after mating.