Department of Poultry Science, Nutrition and Health Promotion, Mississippi State University, Mississippi State, MS 39762, USA.
Department of Food Science, Nutrition and Health Promotion, Mississippi State University, Mississippi State, MS 39762, USA.
Poult Sci. 2020 Jun;99(6):3266-3279. doi: 10.1016/j.psj.2020.03.024. Epub 2020 Apr 11.
Genetic selection in broilers has resulted in improved growth performance, meat yield, and feed conversion efficiency. However, consumers have become increasingly concerned about modern broiler welfare that is related to their rapid growth rate, which may be alleviated by nutrient dilution. This study was conducted to investigate the effects of dietary amino acid (AA) reduction on the growth performance and internal organ development of different genetic strains of broilers. A randomized completed block design with a factorial arrangement of 10 treatments (5 strains × 2 AA levels) was used. The 5 different strains of broilers were fed either a control diet, with digestible AA (lysine, total sulfur AA, and threonine) at the highest recommended levels for the 5 strains, or an AA-reduced diet, with the digestible AA being 20% lower than the control diet. Feed conversion ratio was increased by AA reduction in all 5 strains during day 0-14, 14-28, and 28-41 but was not affected from day 41-55. Body weight and feed intake responses to AA reduction varied in the different strains and ages of birds. Liver weight relative to BW on day 40, and weights of the duodenum and jejunum relative to BW on day 60 were increased by decreasing the dietary AA concentration. These results indicate that the birds had adjusted their organ growth and metabolism in response to increases in digestion, absorption, and utilization efficiency to accommodate a decrease in dietary AA content. Surprisingly, the cost of feed required to produce the same BW was decreased in 4 of 5 strains on both day 41 and 55, which was largely because of the lower price of the diets containing reduced AA levels and the later compensatory growth experienced by the birds fed AA-reduced diets. In the future, when dietary AA levels need to be adjusted to control growth rate and improve welfare status, the genetic strain, age of the birds, and targeted goals need to be taken into consideration.
肉鸡的遗传选择导致其生长性能、肉质产量和饲料转化率得到了提高。然而，消费者越来越关注现代肉鸡的福利问题，这与它们的快速生长速度有关，而通过营养稀释可以缓解这一问题。本研究旨在探讨饲粮氨基酸（AA）降低对不同遗传品系肉鸡生长性能和内脏器官发育的影响。采用完全随机区组设计，设 10 个处理（5 个品系×2 个 AA 水平）的析因试验设计。5 个不同品系的肉鸡分别饲喂基础日粮（可消化赖氨酸、总含硫氨基酸和苏氨酸满足 5 个品系的最高推荐水平）或 AA 降低日粮（可消化 AA 比基础日粮低 20%）。在 0-14 日龄、14-28 日龄和 28-41 日龄，所有 5 个品系的肉鸡饲粮 AA 降低都会导致饲料转化率升高，但在 41-55 日龄没有影响。不同品系和日龄的肉鸡对 AA 降低的体重和采食量反应不同。40 日龄时，肝重与 BW 的比值以及 60 日龄时十二指肠和空肠重与 BW 的比值随 AA 浓度的降低而增加。这些结果表明，鸡通过调整器官生长和代谢来适应消化、吸收和利用效率的提高，以适应饲粮 AA 含量的降低。令人惊讶的是，在 5 个品系中，有 4 个品系在 41 日龄和 55 日龄时，生产相同 BW 的饲料成本降低，这主要是由于含较低 AA 水平的日粮价格较低，以及饲喂 AA 降低日粮的鸡只后期的补偿性生长。在未来，当需要调整饲粮 AA 水平来控制生长速度和改善福利状况时，需要考虑遗传品系、鸡的日龄和目标。
