Effect of Valine to Lysine Ratios on Growth Performance, Carcass Characteristics, and Immune Response in Broiler Chickens

The present study aimed to investigate the effect of dietary valine supplementation on growth, carcass characteristics, and immune response in broilers. One day old eight hundred and forty broiler chicks were raised on iso-nitrogenous and iso-calorie diets (starter (1-10 days) CP 22%, ME 2975 kcal/kg), grower (11-21 days) CP 20%, ME 3025 kcal/kg) and finisher (22-35 days) CP 19%, ME 3100 kcal/kg) respectively. These birds were randomly consigned to one negative control group (V:L68, 68% valine to lysine ratio), one control group (V:L73, 73% valine to lysine ratio) and four treatments; V:L78 (78% valine to lysine ratio), V:L83 (83% valine to lysine ratio), V:L88 (88% valine to lysine ratio), V:L93 (93% valine to lysine ratio) with seven replication per treatment and 20 birds per replicate. During both the starter (0-3 weeks) and finisher phase (4-5 weeks), parameters such as body weight (BW), average daily gain (ADG), average daily feed intake (ADFI), and FCR remained unaffected (P > 0.05) by treatments in ration diet. However, during the overall period (0-35 days) average daily feed intake (ADFI) was higher (P < 0.05) of birds fed V:L88 (88% valine to lysine ratio) diets compared to other treatments (V:L68, V:L73, V:L78, V:L83, V:L93). Dressing percentage and relative thymus weight were higher (P < 0.05) in birds offered V:L88 diets than in the respective treatments. Both on days 17 and 35 Antibody titer averse to Newcastle disease (ND) virus was better (P < 0.05) in birds receiving V:L93 (93% valine to lysine ratio) diets than the rest of the treatments. Birds offered V:L93 diets had higher (P < 0.05) Ca and P concentrations in bones than in other treatments. Overall, enhancing valine to lysine ratio than the recommendation of Cobb-Vantress did not improve growth performance, or carcass characteristics, however, it improved bone mineralization and immune status in broilers.