University Clinic for Swine, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria.
Agri-Food and Biosciences Institute, Agriculture Branch, Hillsborough, Northern Ireland, United Kingdom.
Poult Sci. 2018 Feb 1;97(2):578-591. doi: 10.3382/ps/pex332.
The contribution of the intestinal tract to differences in residual feed intake (RFI) has been inconclusively studied in chickens so far. It is also not clear if RFI-related differences in intestinal function are similar in chickens raised in different environments. The objective was to investigate differences in nutrient retention, visceral organ size, intestinal morphology, jejunal permeability and expression of genes related to barrier function, and innate immune response in chickens of diverging RFI raised at 2 locations (L1: Austria; L2: UK). The experimental protocol was similar, and the same dietary formulation was fed at the 2 locations. Individual BW and feed intake (FI) of chickens (Cobb 500FF) were recorded from d 7 of life. At 5 wk of life, chickens (L1, n = 157; L2 = 192) were ranked according to their RFI, and low, medium, and high RFI chickens were selected (n = 9/RFI group, sex, and location). RFI values were similar between locations within the same RFI group and increased by 446 and 464 g from low to high RFI in females and males, respectively. Location, but not RFI rank, affected growth, nutrient retention, size of the intestine, and jejunal disaccharidase activity. Chickens from L2 had lower total body weight gain and mucosal enzyme activity but higher nutrient retention and longer intestines than chickens at L1. Parameters determined only at L1 showed increased crypt depth in the duodenum and jejunum and enhanced paracellular permeability in low vs. high RFI females. Jejunal expression of IL1B was lower in low vs. high RFI females at L2, whereas that of TLR4 at L1 and MCT1 at both locations was higher in low vs. high RFI males. Correlation analysis between intestinal parameters and feed efficiency metrics indicated that feed conversion ratio was more correlated to intestinal size and function than was RFI. In conclusion, the rearing environment greatly affected intestinal size and function, thereby contributing to the variation in chicken RFI observed across locations.
到目前为止，肠道对残余采食量（RFI）差异的贡献在鸡中尚未得到明确研究。在不同环境中饲养的鸡，其与 RFI 相关的肠道功能差异是否相似也不清楚。本研究的目的是研究在两个不同地点（L1：奥地利；L2：英国）饲养的 RFI 差异较大的鸡的养分保留、内脏器官大小、肠道形态、空肠通透性以及与屏障功能和先天免疫反应相关的基因表达的差异。实验方案相似，在两个地点都使用相同的饲粮配方。从第 7 天开始，记录鸡（科宝 500FF）的个体体重（BW）和采食量（FI）。在 5 周龄时，根据 RFI 将鸡（L1，n = 157；L2 = 192）进行排序，并选择低、中、高 RFI 鸡（n = 9/RFI 组，性别和地点）。同一 RFI 组内的两个地点的 RFI 值相似，且雌性和雄性鸡的低 RFI 到高 RFI 的 RFI 值分别增加了 446 和 464 g。地点而不是 RFI 等级影响生长、养分保留、肠道大小和空肠二糖酶活性。与 L1 相比，L2 鸡的总体重增加较少，黏膜酶活性较低，但养分保留较高，肠道较长。仅在 L1 测定的参数显示，低 RFI 雌性鸡的十二指肠和空肠隐窝深度增加，旁细胞通透性增强。L2 时低 RFI 雌性鸡的 IL1B 表达低于高 RFI 雌性，而 L1 时的 TLR4 和两个地点的 MCT1 表达高于低 RFI 雄性。肠道参数与饲料效率指标之间的相关性分析表明，与 RFI 相比，饲料转化率与肠道大小和功能的相关性更高。总之，饲养环境极大地影响了肠道的大小和功能，从而导致在不同地点观察到的鸡 RFI 变化。
