Responses of broiler chicks raised under constant relatively high ambient temperature to enzymes, amino acid supplementations, or a high-nutrient diet

The objective of this work was to elucidate the responses of growth performance, carcass characteristics, internal organs, carcasses composition, apparent digestibility of nutrients, and efficiency of nutrient retentions of broiler chicks raised under constant relatively high ambient temperature to enzymes (multi-enzymes vs. phytase), or increased SAA level, or arginine level, or increased nutrient concentration (high-nutrient diet). 360 male, 14 d old broiler chicks (ROSS) were assigned to 6 isonitrogenous dietary treatments. The control diet was fed with or without 1 g multi-enzymes/kg diet or 500 FTU phytase/kg diet, or 10% increased concentration of SAA by DL-methionine, or 10% increased concentration of arginine, or 10% increased dietary density including ME, SAA, lysine, Ca, P, trace minerals and vitamins. Each treatment was replicated six times with 10 broilers each. The experimental period lasted from 14-35 d of age. The temperature averaged 33.1°C with 41.9% RH, 30.1°C with 42.8% RH and 29.1°C with 53.4% RH during 14-21, 22-28, and 29-35 d of age, respectively. Feeding diets with 10% increased nutrient concentration (except crude protein) improved growth, FCR, protein retention efficiency, and protein efficiency ratio by 8.0, 7.6, 8.7, and 8.5%, respectively, with no negative impact on carcass characteristics, internal organs, chemical composition, and plasma constituents compared with the control group. The dietary supplementation with either multi-enzymes supplementation, or increased dietary SAA, or arginine by 10% had no positive effect on growth performance, carcass characteristics, chemical composition of carcasses, and apparent digestibility of nutrients and efficiency of nutrient retentions. Phytase addition showed similar effects, except that it significantly improved phosphorus retention by 21.4% and reduced excrement phosphorus by 21.9%, which can contribute to reduce phosphorus related environmental pollution in hot regions.