Optimal dArg to dLys ratio of male broilers from 28 to 42 days of age during a constant, elevated temperature

The effects of environmental temperatures on live performance and carcass characteristics of broilers have been well documented [1, 2, 3]. In addition, Cahaner et al. [4] reported that nutritional requirements are affected by variations in ambient temperature. Amino acid requirements and digestibility in broilers and laying hens at high temperatures is known to vary from those that are raised at ambient temperatures (5, 6, 7, 8). In order to alleviate the effects of high environmental temperatures, research has focused on environmental approaches such as ventilation [9] and stocking density [10] and nutritional approaches such as increasing the nutrient density of the diet [1], decreasing protein concentration [11], fortifying rations with vitamins and minerals [12] and increasing the digestible arginine to digestible lysine ratio (dArg:dLys) of the diet [13]. Research reports by Cuca and Jensen [14] and Labadan et al. [15] addressed the arginine (Arg) needs of broilers throughout the grow-out period. Additional research has evaluated the Arg requirements of young broilers at different environmental temperatures [16, 17], the ileal digestibility of Lys and Arg in heat stressed broilers [8], the effects of varying Arg:Lys ratios and source of methionine at high environmental temperatures [3, 18], and the influence of dietary lysine and dArg:dLys ratio on live performance of broilers [19]. However, very few reports have addressed the optimum dArg:dLys ratio for performance, carcass and breast meat yield at high temperature regimens, particularly in a feeding period close to slaughter.