Glycerol inoculation in eggs of young broiler breeders at different embryonic periods

Small eggs have lesser amounts of nutrients to be used by the embryo, and the yolk glycerol is the main substrate for glycogen production, which is the main energy source in the last days of incubation. Thus, the present study aimed to assess the effect of a glycerol injection in light weight eggs at 2 different days of incubation. To this end, 336 light eggs (55.6 to 58.6 g) from 32-wk-old broiler breeders were incubated. The eggs were divided into 3 treatment groups: 1 group inoculated with saline solution on the 17th d of embryonic development (E17) (control group), the second group injected with a 6 mg glycerol/mL solution at E17, and the third group injected with 6 mg glycerol/mL on the 18th d of incubation (E18). Incubation parameters, liver and muscle glycogen, and broilers performance at 7 d of age were evaluated. Glycerol administration in ovo did not influence hatchability, period of embryonic death or early hatching. Chicks exposed to glycerol in ovo feeding (IOF) used more yolk than birds inoculated with saline solution. Glycerol inoculation at E18 enhanced liver glycogen deposition (P = 0.001) and also improved broilers performance at 7 d, although this improvement in performance and glycogen reserves was not observed when eggs were inoculated at 17 d of incubation. Birds receiving glycerol IOF at E18 showed higher feed intake and body weight gain when compared to the control group and the group inoculated at E17. It was found that glycerol inoculation in light eggs at the 18th d of incubation contributed to raise liver glycerol levels and also to improve broilers performance at 7 d.