Effect of in ovo copper and iron feeding on post-hatch growth and differential expression of growth or immunity related genes in broiler chickens

A study was undertaken to investigate the role of in ovo feeding of copper (Cu) or iron (Fe) supplementation on embryonic, posthatch growth and expression profile of growth and immunity related genes in broiler chickens. In ovo injections (n=300) were carried out on 14^th day of incubation, into the yolk sac/amnion of the developing embryo. In ovo injection of Cu or Fe did not affect the hatchability. No difference (P<0.05) was observed in the day-old or 14^th day post-hatch (PH) chick weight but Fe injected chicks had higher body weight on 42^nd day. Additionally, Fe injection had higher expression of chicken growth hormone (cGH) at 18^th embryonic day (ED) and 7^th day PH, while Cu injection had higher expression of insulin like growth factor- II (IGF-II) at 20^th ED. Expression of IGF-II gene was also higher at 7^th day post-hatch in Fe injected chicks. Higher thymus weight was recorded in Cu and Fe injected chicks at hatch. In vivo response to SRBC (humoral) and PHAP (cellular) was significantly better (P<0.05) in Cu injected chicks. Up regulation of IL-6 gene expression was seen in Cu or Fe injected chicks, while TNFα gene expression was higher only in Fe injected chicks than in control. Cu injected chicks had significantly higher (P<0.05) expression of IL-12 gene, while no variation was observed in iNOS gene expression. It was concluded that in ovo feeding of Fe might help in improving the growth performance and that of Cu could enhance the immune response in broilers.