Effect of oral drenching of glycerin as a source of pre mating energetic supplementation on reproductive response in goats
The availability of glycerol has increased because of the biofuels industry, and glycerol can have a significant effect on reproductive efficiency when used as an alternative energy source in animal feeds. The aim of this study was to investigate the effects of pre mating oral drenching of glycerin on ovarian and fertility responses in goats. Sixty Anglonubian mixed breed goats were submitted to estrus synchronization by CIDR prostaglandin PGF2a treatment and mated. At CIDR removal, onset of estrus, and 24 h after estrus behavior, the animals received 150 ml of saline solution (control group, n 20) 150 ml of glycerol (150 ml group, n 20) or 300 ml of glycerol (300 ml group, n 20) The administration of glycerin increased plasma glucose in the 300 ml group (P 0.05) and the insulin concentration at 12 h after glycerin drenching in both treated groups. Goats from the 300 ml group showed a lower ovulation rate when compared to the control group (1.15 0.08 vs. 0.89 0.14; P 0.05) but exhibited larger follicles at 48, 24, and 12 h prior to ovulation (P 0.05) Administration of 300 ml of glycerol was also associated with a significant reduction in the pregnancy rate (80.00% vs. 38.89% P 0.05) and in pregnant animals it was associated with lower growth of embryonic vesicles (1.78 0.07 mm/day vs. 1.31 0.07 mm/day; P 0.05) compared to the control treatment. Gestational losses in the 300 ml group occurred between mating and the 45th day of pregnancy. No differences were found for the reproductive parameters analyzed in the study between the 150 ml and control groups. In conclusion, the supplementation with glycerol before the mating did not appear to be a viable alternative to increase reproductive efficiency of adult does.