Influence of dietary energy on growth, immunecompetence and carcass characteristics of coloured broiler chickens

An experiment was conducted to assess growth performance, immunecompetence and carcass traits in coloured (Krishibro, PDP, ICAR) broiler chickens (n = 270) fed three isonitrogenous diets (20% CP) but varied in energy levels viz. 2600 (low), 2700 (medium) and 2800 (high) kcal ME/kg diet. Data on biweekly body weight gain were recorded and feed conversion ratio was calculated. On d 42 and 56 of age, chicks from three replicates (15 birds) in each dietary group were injected with sheep red blood cells (SRBC) to measure humoral immune response. On 56d of age, other two replicates from each diet were inoculated with E. coli (serotype O2). The response to SRBC and E. coli inoculation was measured after 5days of inoculation. At 43d of age, chicks from another two replicates (10 birds) under each dietary group were injected intradermally in wattle with phytohaemagglutinin-P (PHA-P) and thickness was measured 24h post inoculation to assess cutaneous basophilic hypersensitivity (CBH) response. On 57th day, 10 birds from each dietary group were slaughtered and data on carcass traits were recorded. The body weight gain increased and feed conversion ratio improved significantly (P<0.05) in chicks fed medium (2700 kcal/kg) energy diet as compared to the lower (2600 kcal/kg) energy diet both at 42 and 56days of age, however, no difference could be found between medium and high (2800kcal/kg) energy diet. The humoral immune response to SRBC, CBH response to PHA-P, lesion scores to E. coli inoculation and carcass characteristics did not differ significantly due to variation in dietary energy (2600 to 2800 kcal ME/kg). It is concluded that 2700 kcal ME/kg diet is adequate for optimum performance of coloured (Krishibro) broiler chickens during 0 to 56 days of age.