Wageningen Livestock Research, 6700 AH Wageningen, the Netherlands.
ForFarmers, Kwinkweerd 12, 7241 CW Lochem, the Netherlands.
Poult Sci. 2019 Oct 1;98(10):4868-4877. doi: 10.3382/ps/pez229.
A study with 884 Ross 308 male broilers, housed in 68 floor pens (0.75 m2) from 0 to 35 days of age was conducted to evaluate the effects of low crude protein (CP) diets, with partial replacement of soybean meal by free amino acids (AA), on performance, slaughter yields, litter quality and footpad lesions. During the first 11 d, all broilers received the same control starter diet (216 g/kg CP, 11.5 g/kg apparent fecal digestible (AFD) lysine, and 2900 kcal/kg AMEn). Thereafter, four experimental feeding programs with different levels of dietary CP (control and control with 1% (CP-1%), 2% (CP-2%) and 3% (CP-3%) less CP units) were provided in both the grower and finisher phase. In the control grower and finisher diet, the CP content was 208 and 198 g/kg, respectively. All diets were formulated to meet or exceed the recommendations concerning AFD AA, and to be iso-caloric within each feeding phase. Feed and water were provided for ad libitum intake during the entire experimental period. None of the low CP feeding programs affected body weight gain, feed intake or mortality from 0 to 35 d. However, CP conversion was improved with the reduction of CP content of the diet. Broilers fed the CP-2% or CP-3% feeding program had an improved feed conversion ratio. Broilers fed the low CP protein feeding programs had a better litter quality and less footpad lesions, compared to broilers fed the control feeding program. Broilers fed the CP-3% feeding program had a lower breast meat yield than broilers fed the control feeding program. Slaughter yields of broilers fed CP-1% or CP-2% feeding program did not differ from the control feeding program. This study demonstrated that the CP content of grower and finisher diets can be reduced by 2.2-2.3% units without adverse effects on growth performance of broilers, while CP reduction seems promising to reduce nitrogen excretion from broiler houses, improve bird welfare, and reduces dependence on vegetable protein sources.
一项针对 884 只罗斯 308 雄性肉鸡的研究，这些肉鸡在 0 至 35 日龄时被饲养在 68 个地板围栏中（0.75 平方米），以评估低粗蛋白（CP）日粮的效果，其中大豆粉被部分用游离氨基酸（AA）替代，对生产性能、屠宰产量、垫料质量和脚垫病变的影响。在最初的 11 天里，所有肉鸡都接受相同的对照起始日粮（216 g/kg CP、11.5 g/kg 表观粪便可消化赖氨酸和 2900 千卡/kg AMEn）。此后，在生长和育肥阶段提供了四个不同 CP 水平的实验饲养方案（对照和对照+1%（CP-1%）、2%（CP-2%）和 3%（CP-3%）CP 单位较少）。在对照生长和育肥日粮中，CP 含量分别为 208 和 198 g/kg。所有日粮的配制均满足或超过了有关 AA 的 AFD 推荐值，并在每个饲养阶段保持等热量。在整个实验期间，饲料和水都可以自由摄入。从 0 至 35 日龄，低 CP 饲养方案均未影响体重增加、饲料摄入或死亡率。然而，随着日粮 CP 含量的降低，CP 转化率得到提高。饲喂 CP-2%或 CP-3%饲养方案的肉鸡，饲料转化率得到改善。与饲喂对照饲养方案的肉鸡相比，饲喂低 CP 蛋白质饲养方案的肉鸡垫料质量更好，脚垫病变更少。饲喂 CP-3%饲养方案的肉鸡的胸肉产量低于饲喂对照饲养方案的肉鸡。饲喂 CP-1%或 CP-2%饲养方案的肉鸡的屠宰产量与对照饲养方案没有差异。本研究表明，生长和育肥日粮的 CP 含量可以降低 2.2-2.3%单位，而不会对肉鸡的生长性能产生不利影响，而 CP 减少似乎有望减少肉鸡舍的氮排泄，改善鸟类福利，并减少对植物蛋白源的依赖。
