Hatchability rate and embryonic growth of broiler chicks following in ovo injection royal jelly.

1. The objectives of this study were to compare the hatchability, chick body and internal organs weights and plasma testosterone concentration of hatchlings after in ovo administration of royal jelly (RJ) on d 7 of incubation. 2. Fertile eggs (n = 150) were injected into the air sac or yolk sac with 0.5 ml normal saline solution or normal saline and pure RJ. The eggs were randomly divided into 5 groups of 30 eggs each: NC, control eggs receiving no injection; ASA, air sac-injected eggs given normal saline solution; ARJ, air sac-injected eggs injected with pure RJ; YSA, yolk sac-injected eggs receiving normal saline solution and YRJ, yolk sac-injected eggs given pure RJ. 3. Injection of RJ significantly decreased hatchability (46.7%) compared with injection of saline solution (68.3%). Hatchability was lower in ARJ (33.3 %) and YRJ (60.0%) groups than in the NC group (90.0%). Hatchability in ASA (70.0%) and YSA (66.66%) groups were comparable to the NC group. 4. In ovo injection of RJ into both sacs increased chicks' absolute and relative body, heart, liver and testes weights compared to the control group whereas plasma testosterone concentration was similar among the different groups. 5. It was concluded that in ovo injection of RJ may be an effective method to increase the body weight of hatched chicks as an absolute value (CWT) and chicks' internal organ weights.