Department of Animal Sciences, Purdue University, West Lafayette, IN 47907-2054, USA.
Poult Sci. 2012 Apr;91(4):899-907. doi: 10.3382/ps.2011-01777.
The effects of mild coccidial vaccine (5× dose) challenge and fiber levels on ileal endogenous amino acid (EAA) losses was determined in 26-d-old broiler chickens using the regression method. Birds were fed semipurified diets containing 3 levels of casein (40, 80, or 120 g/kg of diet) as the only source of dietary protein at 2 levels of fiber (purified cellulose at 25 or 75 g/kg of diet). One half of the experimental birds were gavaged with coccidial vaccine on d 20. The 3 levels of casein were used to determine EAA losses for each replicate cage of birds. The design of the study was a randomized complete block employing a factorial arrangement of treatments with 2 levels of coccidial challenge (control or unchallenged, and challenged) and 2 levels of fiber, with 6 replicate cages per treatment and 8 birds per cage. Birds were killed on d 26 and contents from the entire ileum were flushed with distilled water and stored at -20°C until processed. Ileal EAA losses were determined from the ordinate intercept, at zero amino acid (AA) intake, of the regression of ileal digesta AA concentration in milligrams per kilogram of DM intake against dietary AA intake in milligrams per kilogram of DM. The effect of fiber level on EAA losses, expressed in milligrams per kilogram of DM intake, were higher (P < 0.05) for most of the AA in birds fed 25 g of fiber/kg of diet. Coccidial vaccine challenge decreased (P < 0.05) EAA losses for 8 of the 18 AA. A significant interaction between fiber level and coccidial vaccine challenge was obtained for all AA except His and Lys. Coccidial vaccine challenge resulted in increased (P < 0.05) NaPi-IIb expression. The results suggest that ileal EAA loss is higher in challenged birds fed the diet containing 25 g of fiber/kg of diet. Changes in EAA losses as a result of dietary fiber level and coccidial infection are important in amino acid nutrition of the broiler chicken.
采用回归法，研究了轻度球虫疫苗（5 倍剂量）挑战和纤维水平对 26 日龄肉鸡回肠内源性氨基酸（EAA）损失的影响。试验鸡饲喂以 3 种水平的酪蛋白（日粮中 40、80 或 120g/kg）作为唯一蛋白源的半纯化日粮，日粮纤维水平分别为 25 或 75g/kg 的纯化纤维素。试验鸡的一半在第 20 天进行球虫疫苗灌胃。采用 3 种水平的酪蛋白，确定每重复鸡笼的 EAA 损失。本研究设计采用随机完全区组设计，处理因素为 2 个球虫挑战水平（对照或未挑战，以及挑战）和 2 个纤维水平，每个处理有 6 个重复鸡笼，每个鸡笼 8 只鸡。第 26 天鸡只被处死，整个回肠内容物用蒸馏水冲洗并保存在-20°C，直至处理。通过回肠食糜 AA 浓度与日粮 AA 摄入毫克数相对于 DM 摄入毫克数的回归的纵坐标截距，确定回肠 EAA 损失。在饲喂 25g/kg 纤维日粮的鸡中，大多数 AA 的纤维水平对 EAA 损失的影响更高（P＜0.05）。球虫疫苗挑战降低了 18 种 AA 中的 8 种的 EAA 损失（P＜0.05）。除 His 和 Lys 外，所有 AA 都观察到纤维水平和球虫疫苗挑战之间存在显著的相互作用。球虫疫苗挑战导致 NaPi-IIb 表达增加（P＜0.05）。结果表明，在饲喂含 25g/kg 纤维日粮的挑战鸡中，回肠 EAA 损失更高。日粮纤维水平和球虫感染引起的 EAA 损失变化对肉鸡的氨基酸营养很重要。
