Growth, immune competence and resistance to Escherichia coli in White Leghorn chicks as influenced by dietary energy levels

An experiment was conducted to measure growth, immunocompetence, and resistance to Fscherichia coli in layer chicks from 0–8 weeks of age. At day old, two hundred and seventy White Leghorn layer chicks were weighed, wing banded and distributed randomly into three dietary groups of fifteen replicates in each. Each replicate contained six chicks comprising of three from either sex. The chicks were fed with diet containing three different levels of energy i.e. 2500, 2600 and 2700 Kcal ME/kg diet and these diets were referred as low. medium and high energy diet respectively. At 14 and 28 days of age, the body weight of chicks were significantly higher in the medium and high energy dietary group as compared to that of low energy. At 42 and 56 days of age the body weights of chicks were significantly higher in medium energy diet as compared to low energy diet. For 0–14 days and 0–42 days the feed conversion ratio of chicks were significantly improved in the high and medium energy diet as compared to that of low energy diet, however no difference was observed among the dietary groups for 0–28 day. For 0–56 days of age, the feed conversion ratio was significantly improved in the high-cnergy dietmy group compared to that of low energy, however no difference was observed between medium and high energy dietmy group. The antibody titre in response to SRBC inoculation and percent relative weight of bursa and spleen did not differ signilicantly among the dietmy groups. The CBH response and phagocytic index was significantly higher in the high and medium energy dietary groups as compared to that of low energy dietary group. The effect of different level of dietary energy on lesion score in response to E. coli inoculation and % relative weight of spleen and bursa were found to be non significant.