The effects of in-ovo injection of leptin in broiler breeder eggs on hatchability and broiler performance

This study was conducted to determine the effects of in-ovo leptin injection on hatching parameters and broiler performance. A total of 1000 fertile eggs were obtained from a broiler breeder flock (Ross 308) and divided into 4 treatment groups. Two groups were used as sham control (injected with 1 ml phosphate buffer solution) an un-injected control. Other two groups were injected with 1 µg leptin before setting (L1 group) and at the 5th day of the incubation (L5 group). Hatchability, embryonic mortality, chick quality characteristics were evaluated. The hatched chicks from each group (except sham control group) were randomly assigned to 4 replication and reared under standard condition. Broiler performance (body weight, feed efficiency, viability) were determined. It was obtained that in-ovo leptin injection significantly affected hatchability, hatching time, embryonic mortality, chick weight, chick length and yolk sac weight. However, there were no significant differences between treatment groups in yolk free chick weight. Hatchability was decreased by in-ovo leptin injection rather than controls. The earliest hatching, the heaviest chick weight, the longest chick length and the heaviest yolk sac weight were obtained in the L5 group. Final body weight (42d) of L5 group was not different from that of control group. However, L1 group had lower final body weight than the controls. In-ovo leptin injection caused a significant decrease in food consumption and feed efficiency increased considerably. As a result, in-ovo leptin injection caused some decreases in hatchability of fertile eggs but improved chick quality and reduced feed consumption without a significant decrease in final body weight. In conclusion, it seems to be possible that in-ovo leptin injection at 5th day of incubation can be used to decrease feed consumption without adverse effect on growth performance in broiler chicken. Keywords: leptin, in-ovo injection, hatchability, broiler performance, feed intake, feed efficiency