In ovo administration of recombinant human insulin-like growth factor-I alters postnatal growth and development of the broiler chicken

Two experiments assessed the efficacy of in ovo administration of insulin-l ike growth factor-I (IGF-I) to enhance skeletal muscle development and impr ove feed efficiency of broilers. Hatching eggs were divided into three grou ps: uninjected control, vehicle-injected control, and recombinant human (rh ) IGF-I (100 ng per embryo). Eggs in Experiment 1 were injected on Day 1, 4 , or one of Day 7 through 18 of incubation. Growth rates for Days 1 and 4 r esulted in the greatest response to treatment (P < 0.01, P < 0.06 respectiv ely). Based on these results, Experiment 2 focused on Days 1 to 4 of incuba tion. Results from Experiment 2 showed that there was no significant differ ence in hatchability among control and rh IGF-I treatment groups. Injection on Day 3 resulted in the greatest response for increased live (P < 0.035) and leg (P < 0.02) weights in both sexes. Feed efficiencies of all rh IGF-I groups were significantly (P < 0.01) improved for the first 3 wk. In ovo a dministration of rh IGF-I on Day 3 increased feed efficiency (6.65%; P < 0. 009) in pens of mixed-sex broilers. In addition, live weights (12.3%; P < 0 .002), leg weights (11.7%; P < 0.01), breast weights (9.9%; P < 0.04), and heart weights (11.4%; P < 0.02) were increased in males. These results demo nstrate that in ovo administration of rh IGF-I alters feed efficiency, grow th, and tissue development. This finding lends itself to significant improv ements in broiler production efficiency and profitability.