Individual and combined effects of in-ovo injection of creatine monohydrate and glucose on somatic characteristics, energy status, and posthatch performance of broiler embryos and hatchlings

Two trials were conducted to investigate the individual and combined effects of in-ovo injection of creatine monohydrate ( CMH: ) and glucose on the somatic characteristics and energy status of broiler embryos and hatchlings and the growth performance of chicks during the first wk posthatch. In trial 1, 550 17.5-day-old living, fertile eggs were randomly assigned to 1 of 5 treatment groups, including 1) a noninjected control, 2) a 0.4 mL diluent-injected control, or 0.4 mL diluents containing 3) 6 mg CMH, 4) 25 mg glucose, or 5) a combination of 6 mg CMH and 25 mg glucose (identified as CMH+G: ). In trial 2, after hatch, 48 hatchlings with individual body weight ( BW: ) close to the average BW of their incubation group were randomly selected and placed in 6 replicates of 8 birds each to evaluate their growth performance during the first wk posthatch. Compared with the noninjected and the 0.4-mL diluent-injected control groups, individual injection of CMH or glucose did not affect the hatching time, hatchability, somatic characteristics, or concentrations of glycogen and glucose in the liver and pectoralis major ( PM: ) muscle, although injection of CMH increased (P < 0.05) concentrations of creatine ( CR: ) and phosphocreatine ( PCR: ) in the PM muscle on d 19 of incubation (E19.5). However, the CMH+G treatment increased (P < 0.05) BW relative to set egg weight ( SEW: ) on E19.5, as well as residual yolk sac weight on the day of hatch. Moreover, the CMH+G treatment also increased (P < 0.05) concentrations of glycogen and glucose in the liver and concentrations of Cr and PCr in the PM muscle on E19.5. Chicks in the CMH+G group also exhibited higher BW gain during the first wk than controls (P < 0.05). These results indicate that combined injection of CMH and glucose during the last stage of incubation have a synergistic effect on improvement of the energy status of embryos and hatchlings, which is useful for enhancing embryo development, and subsequently improving chick growth during the early posthatch stages.