Abstract
We investigated efficacy of in ovo application of epidermal growth factor (EGF) on intestinal expression of EGF receptor (EGFR) during embryogenesis (experiment 1) and posthatch growth performance and gastrointestinal development in broiler chickens (experiment 2). In experiment 1, 450 fertile Ross 708 eggs were allocated to 3 groups (150 eggs/group): 1) control, 2) 160 μg EGF/kg of egg, and 3) 640 μg of EGF/kg of egg. Eggs were candled for live embryos on day 16 and injected with the respective treatment solutions on day 17 and sampled for jejunal tissue from day 17 to hatch for EGFR analyses. There was no effect of EGF (P > 0.05) on EGFR expression on day 17 to 20; however, on day 21, EGF increased (P < 0.05) EGFR expression in EGF birds relative to control birds. In experiment 2, 600 fertile Ross 708 eggs were allocated to 5 treatments: 1) intact, no puncture or injection, 2) punched but not injected, 3) control, no EGF, 4) 80 μg of EGF/kg of egg, and 5) 160 μg of EGF/kg of egg. The eggs were incubated and candled for live embryos on D 19, treated, and subsequently transferred to the hatcher. Upon hatching, chicks were weighed, and 90 chicks per treatment placed in cages (15 birds/cage) and allowed free access to a standard antibiotic-free corn-soybean diet for 21 D. Feed intake and body weight were monitored on a weekly basis. Samples of birds were necropsied on D 0, 7, 14, and 21 for measurements of intestinal weight and jejunal histomorphology and excreta samples taken on D 3 to 5 and 17 to 19 for apparent retention of dry matter. There was no EGF effect (P > 0.05) on any posthatch response criteria. In conclusion, in ovo application of EGF increased EGFR expression but had no effect on posthatch growth performance, DM retention, and intestinal development. The lack of EGF effect on posthatch response was surprising but suggested in ovo application of EGF may not be a viable approach.