1. This study was conducted to assess the effects of graded levels of dietary corn resistant starch (RS) on growth performance, carcass traits, nutrient retention, digestive organ index, intestinal morphology, digestive enzyme activities, and mRNA expression of certain nutrient transporters in broiler chickens.2. A total of 320, 1-d-old Arbor Acres broiler chickens were randomly assigned to five dietary treatments, with eight replicates of eight birds in each. These treatments included one corn-soybean control diet, a corn-soybean based diet containing 20% corn starch, and three diets supplemented with 4%, 8% and 12% RS by replacing corn starch with 6.67%, 13.33% and 20% of Hi-Maize 260® (identified as control, RS1, RS2, RS3 and RS4, respectively). The feeding period lasted 42 days.3. Performance parameters including feed consumption, feed conversion, body weight gain and percentage of abdominal fat at d 42 of age, nutrient retention (including dry matter, fat, total starch and nitrogen free extract), and apparent metabolisable energy was measured from d 18 to 20 and d 39 to 41 and showed negative linear responses to increasing dietary RS level (P < 0.05). Birds fed the RS3 and RS4 diets showed higher relative weight of duodenum, jejunum and ileum, as well as lower villus height and villus height/crypt depth compared to the control (P < 0.05). The activity of pancreatic trypsin of birds at d 21 and 42 of age decreased linearly in response to the increase of dietary RS level (P < 0.01). There were linear changes in up-regulated mRNA expression of SGLT-1 and down-regulated mRNA expression of GLUT-2 with increasing proportion of RS at d 21 and 42 of age (P < 0.05), respectively.4. It was concluded that feeding broilers with diets containing higher concentrations of RS impaired the development of small intestine, which resulted in lower apparent total tract retention of nutrients and poorer body weight gain, feed efficiency and carcass traits of broiler chickens.

中文翻译：

---

饲喂分级水平玉米抗性淀粉日粮的肉鸡的生长性能、胴体性状和消化功能。

1. 本研究旨在评估日粮玉米抗性淀粉 (RS) 分级水平对玉米生长性能、胴体性状、养分保留、消化器官指数、肠道形态、消化酶活性和某些养分转运蛋白 mRNA 表达的影响。肉鸡。2。总共 320 只 1 日龄的 Arbor Acres 肉鸡被随机分配到 5 种日粮处理组，每组 8 只鸡重复 8 次。这些处理包括一种玉米-大豆对照日粮、一种含有 20% 玉米淀粉的玉米-大豆日粮，以及通过用 6.67%、13.33% 和 20% 的玉米淀粉代替玉米淀粉来补充 4%、8% 和 12% RS 的三种日粮。 Hi-Maize 260®（分别标识为对照、RS1、RS2、RS3 和 RS4）。饲养期为42天。 3．性能参数，包括饲料消耗，在 42 天时的饲料转化率、体重增加和腹部脂肪百分比、营养保留（包括干物质、脂肪、总淀粉和无氮提取物）和表观代谢能在 18 至 20 天和 39 至 41 天测量并且对增加的饮食 RS 水平呈负线性反应（P < 0.05）。与对照组相比，饲喂 RS3 和 RS4 日粮的鸡只显示出较高的十二指肠、空肠和回肠相对重量，以及较低的绒毛高度和绒毛高度/隐窝深度（P < 0.05）。随着日粮RS水平的增加，鸡在21天和42天的胰蛋白酶活性呈线性下降（P < 0.01）。SGLT-1 mRNA表达上调和GLUT-2 mRNA表达随着RS比例的增加在21岁和42岁时呈线性变化（P < 0.05），分别。 4。得出的结论是，用含有较高浓度 RS 的日粮喂养肉鸡会损害小肠的发育，从而导致肉鸡明显的全肠道营养保留减少，体重增加、饲料效率和胴体性状较差。