Nitrogen (N) excreted by poultry is converted to ammonia (NH₃), presenting an environmental risk and a health risk to the farmer and animals. A study was performed to investigate the effect of reduced CP and feed form on broiler performance and welfare, meat and litter quality, N utilization, and NH₃ concentrations at litter level. A total of 2,232 Ross 308 male broilers was divided into 6 treatments and 6 replicates, which was fed diets in both pellet and mash forms with different CP levels of 205.0 g/kg (H, high), 187.5 g/kg (M, intermediate) and 175.0 g/kg (L, low) in the grower phase and 195.0 g/kg (H), 180.0 g/kg (M) and 165.6 g/kg (L) in the finisher phase. Individual amino acids (AA) were supplemented to maintain digestible AA-to-digestible lysine ratios. Decreasing dietary CP content to 187.5 g/kg in the grower phase and 180.0 g/kg in the finisher phase reduced NH₃ concentrations at litter level (P < 0.001), but a further reduction in dietary CP had no additional effect. Mash treatments had better litter qualities and lower incidences of foot and hock lesions than pellet treatments at d 38 (P < 0.001). In addition, treatments with reduced CP had lower incidence of foot lesions at d 38 (P < 0.001). Broilers fed pelleted diets had higher ADFI, ADG, and final BW, improved feed conversion ratio (FCR), and heavier carcasses (P < 0.001) than those fed mash diets over a production period of 39 d. Performance could not be maintained when birds were fed L CP pelleted diets. This study demonstrated that, with the supplementation of AA to meet requirements, the concentration of dietary CP can be reduced to 187.5 and 180.0 g/kg in the grower and finisher phases respectively, without impairing broiler performance, meat yield and quality. Mash diets were favorable when considering the overall litter quality and welfare of the birds. However, they could not maintain the same broiler performance and slaughter yield as pelleted diets. Results from the present study may assist the poultry sector towards a socially acceptable low-emission farming system.

家禽排泄的氮（N）转化为氨（NH ₃），对农民和动物带来环境风险和健康风险。进行了一项研究，以调查减少 CP 和饲料形式对肉鸡生产性能和福利、肉和垫料质量、N 利用率和 NH _3的影响垫料水平的浓度。将 2,232 头 Ross 308 雄性肉鸡分为 6 个处理和 6 个重复，分别饲喂颗粒和糊状日粮，不同 CP 水平分别为 205.0 g/kg（H，高）、187.5 g/kg（M，中) 和 175.0 g/kg (L, low) 在生长阶段和 195.0 g/kg (H)、180.0 g/kg (M) 和 165.6 g/kg (L) 在育肥阶段。补充单个氨基酸 (AA) 以维持可消化的 AA 与可消化赖氨酸的比例。在生长阶段将日粮 CP 含量降低至 187.5 g/kg 和在育肥阶段降低 180.0 g/kg 会降低垫料水平的 NH ₃浓度（P < 0.001)，但日粮 CP 的进一步降低没有额外的影响。在第 38 天，与颗粒处理相比，醪处理具有更好的垫料质量和更低的足部和飞节损伤发生率（P  < 0.001）。此外，降低 CP 的治疗在 38 天时足部病变的发生率较低（P  < 0.001）。饲喂颗粒饲料的肉鸡具有更高的 ADFI、ADG 和最终体重，提高了饲料转化率 (FCR)，并且胴体更重（P < 0.001) 在 39 天的生产周期内比饲喂醪饲料的那些。当饲喂 L CP 颗粒饲料时，鸡的性能无法保持。本研究表明，在满足要求的情况下，添加 AA 后，日粮 CP 浓度在生长和育肥阶段可分别降低至 187.5 和 180.0 g/kg，而不会影响肉鸡生产性能、肉产量和质量。考虑到鸡的整体垫料质量和福利时，醪饲料是有利的。然而，它们无法保持与颗粒饲料相同的肉鸡性能和屠宰产量。本研究的结果可能有助于家禽部门建立一个社会可接受的低排放养殖系统。