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 PGF2α 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.