Optimizing metabolizable energy and crude protein levels for enhanced Zootechnical performance, Immune response and Biochemical health indices in CARI-Shyama chickens under tropical conditions

The poultry sector in India plays a vital role in rural income and nutritional security, with increasing focus on improved indigenous breeds like CARI-Shyama which is cross of Kadaknath and CARI Red, noted for their adaptability, black meat and disease resistance. Despite their growing importance, there is limited information on the optimal dietary energy and protein requirements for this breed, particularly concerning growth performance, serum biochemistry, and immune parameters. This research aimed to fill this gap by systematically evaluating the effects of varying dietary metabolizable energy (ME) and crude protein (CP) levels on these parameters in growing CARI-Shyama chickens. A 14-week feeding trial was conducted using 360-day old CARI Shyama chicks assigned to nine dietary treatments in a 3×3 factorial design. The treatments combined three levels of energy (2500, 2700, and 2900 kcal/kg ME) with three levels of protein (16%, 18%, and 20% CP). Growth performance metrics, serum biochemical profiles, and immune responses were assessed using standard analytical and immunological assays. Results revealed that birds fed a diet containing energy (2500 kcal/kg ME) and crude protein (16% CP) exhibited optimum cumulative body weight gain, despite increased feed intake and a slightly higher feed conversion ratio (FCR), compared to higher energy and protein diets. Serum biochemical parameters indicated enhanced protein utilization at higher protein levels, while immune function, assessed via cell-mediated and humoral responses, remained unaffected across dietary treatments. In conclusion, a dietary regimen comprising 2500 kcal/kg ME and 16% CP adequately support growth, metabolic health, and immune competence in CARI Shyama chickens. These findings provide valuable insights for developing cost-effective, nutritionally balanced feeding strategies suitable for this slow-growing indigenous genotype, promoting sustainable backyard poultry production in India.