The objective of this study was to investigate the effects of dietary crude protein (CP) concentrations, grain types and arginine:lysine ratios on performance parameters of broiler chickens. The 2 × 2 × 2 factorial array of dietary treatments harnessed two CP concentrations (210 and 170 g/kg), two feed grains (wheat and sorghum), and two arginine:lysine ratios (104 and 110). Each dietary treatment was offered to 7 replicates of 14 birds per floor pen, a total of 784 off-sex male, Ross 308 broilers, from 14 to 35 d post-hatch. The dietary CP reduction compromised weight gain by 10.0% (2078 versus 2310 g/bird) as a main effect and FCR by 7.51% (1.474 versus 1.371), subject to an interaction. In a three-way interaction (P = 0.008), expanded arginine:lysine ratios improved FCR by 2.30% in 170 g/kg CP, sorghum-based diets but compromised FCR by 2.12% in corresponding wheat-based diets. Sorghum was the more suitable feed grain in reduced-CP diets as sorghum generated significant advantages in weight gain of 7.59% (2154 versus 2002 g/kg) and FCR of 6.94% (1.421 versus 1.527) in birds offered 170 g/kg CP diets. Both dietary CP and feed grain generated significant and divergent impacts in apparent ileal digestibility coefficients for the majority of 16 assessed amino acids. Dietary CP reductions increased non-bound amino acid inclusions (NBAA) in wheat-based diets (48.96 versus 9.80 g/kg) to a greater extent than sorghum-based diets (35.3 versus 9.50 g/kg) and increasing dietary NBAA inclusions were linearly associated with compromised weight gain (r = −0.834; P < 0.001) and FCR (r = 0.862; P < 0.001). Increasing ratios of free arginine to lysine plasma concentrations were linearly (r = −0.466; P = 0.004) related to improvements in FCR. The implications of the observed outcomes are discussed and possible explanations are advanced.

本研究的目的是调查日粮粗蛋白 (CP) 浓度、谷物类型和精氨酸：赖氨酸比例对肉鸡生产性能参数的影响。2×2×2 日粮处理的因子阵列利用了两种CP浓度（210和170g/kg）、两种饲料谷物（小麦和高粱）以及两种精氨酸：赖氨酸比率（104和110）。孵化后 14 至 35 天，每个楼层围栏 14 只鸡，总共 784 只异性雄性肉鸡，Ross 308 只肉鸡，进行 7 个重复的饮食处理。饮食 CP 减少的主要影响是体重增加 10.0%（2078 克/只与 2310 克/只），FCR 减少 7.51%（1.474 与 1.371），存在相互作用。在三向相互作用中（P  = 0.008），在 170 g/kg CP、以高粱为基础的日粮中，扩大精氨酸：赖氨酸比例可使 FCR 提高 2.30%，但在相应的以小麦为基础的日粮中，FCR 会降低 2.12%。高粱是低CP日粮中更合适的饲料谷物，因为在提供170克/千克CP日粮的家禽中，高粱产生了显着的优势，体重增加了7.59%（2154克/千克对2002克/千克），饲料转化率达到6.94%（1.421对1.527）。 。日粮 CP 和饲料谷物对 16 种评估氨基酸中的大多数的表观回肠消化率系数产生显着且不同的影响。膳食CP减少增加了以小麦为基础的日粮中的非结合氨基酸含量（NBAA）（48.96与9.80 g/kg），其程度高于以高粱为基础的日粮（35.3与9.50 g/kg），并且膳食NBAA含量的增加呈线性关系与体重增加受损（r  = -0.834；P  < 0.001）和 FCR（r  = 0.862；P  < 0.001）相关。游离精氨酸与赖氨酸血浆浓度之比的增加 与 FCR 的改善呈线性关系（ r  = -0.466；P = 0.004）。讨论了观察到的结果的含义，并提出了可能的解释。