Optimum site for in ovo amino acid injection in broiler breeder eggs

Three experiments were conducted to evaluate the effect of differences in i n ovo amino acid (AA) injection sites in broiler breeder eggs on subsequent hatchability and BW of chicks. In Experiment 1, an AA solution was injecte d into eggs with 13-mm. or 19-mm, 27-ga. needles. Uninjected eggs served as controls. Hatchability was decreased (P < 0.05) in eggs receiving AA injec tions with the 19-mm needle in comparison to the control and 13-mm-injected groups. However, BW of chicks increased (P < 0.05) relative to pre-incubat ional egg weight by AA injection with the 13-mm. needle. In order to evalua te the in ovo location of AA injections from Experiment 1, India ink was in jected into eggs in Experiment 2 with a 13-or 19-mm needle. Immediately aft er injection, the air cell end of the egg was windowed in order to observe effects of injection site. Windowing of eggs was accomplished by removing a piece of the eggshell over the air cell and the underlying membrane at Day 7 of incubation. The amount of injected India ink was higher in the extra- embryonic coelom in eggs treated by both needles, However, the occurrence o f India ink in the extra embryonic coelom was higher (P < 0.05) in the grou p injected with AA solution using a 13-mm needle as compared to that after injection using a 19-mm needle. The observation of India ink in the amnioti c cavity was higher (P < 0.05) in the group injected with AA solution using a 19-mm needle rather than that using a 13-mm. needle. In Experiment 3, tr eatments consisted of control (uninjected eggs) or windowed eggs. Windowed eggs received AA to the chorioallantoic membrane, the yolk, extra-embryonic coelom, or amniotic cavity at Day 7 of incubation. Hatchability was reduce d, but chicks hatched when eggs were windowed and when AA were injected int o the yolk sac or extra-embryonic coelom. However, chicks did not hatch whe n AA were administered to the chorioallantoic membrane or into the amniotic cavity. These results suggest that the best AA injection sites in ovo may be the yolk and extra-embryonic coelom.