The present research evaluated the effects of graded levels of dietary fibre on growth, digestive and absorptive capacities, and the potential underlying mechanisms in on‐growing grass carp (Ctenopharyngodon idella). Grass carp (123.00 ± 0.70 g) were fed diets with graded levels of neutral detergent fibre (NDF: 97.8, 119.0, 140.2, 159.4, 181.2 and 201.6 g/kg diet) for 60 days. Besides, a 2‐week digestion experiment was conducted to explore the effect of dietary fibre on the apparent digestibility coefficients (ADC) of feed. The results showed that optimum dietary fibre level (140.2 or 159.4 g/kg diet) increased feed intake, per cent weight gain, specific growth rate and the ADC of dietary protein (p < .05); increased the activities of digestive and brush border enzyme; and up‐regulated intestinal amino acid transporter mRNA levels (SLC1A5 and SLC6A19b, p < .05) partially associated with activation of TOR signalling pathway. However, high dietary fibre levels (NDF levels ≥181.2 g/kg diet) were not conducive to the digestion and absorption of nutrients, resulting in the decline of growth performance. Thus, based on the quadratic regression analysis for per cent weight gain and feed efficiency, the optimum (143.9 and 134.5 g/kg diet) and maximum tolerance (189.8 and 171.2 g/kg diet) levels of dietary NDF were estimated for on‐growing grass carp.

中文翻译：

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饲喂分级大豆皮饲料纤维的生长中草鱼（Ctenopharyngodon idellus）的生长性能，消化吸收能力

本研究评估了膳食纤维分级水平对生长的草鱼（Ctenopharyngodon idella）生长，消化和吸收能力的影响以及潜在的潜在机制。给草鱼（123.00±0.70 g）饲喂60级分级中性洗涤剂纤维的饲料（NDF：97.8、119.0、140.2、159.4、181.2和201.6 g / kg饲料）。此外，进行了为期2周的消化实验，以探讨膳食纤维对饲料表观消化系数（ADC）的影响。结果表明，最佳膳食纤维水平（140.2或159.4 g / kg饲料）可提高饲料采食量，增重百分比，比生长速率和膳食蛋白ADC（p <.05）; 增加了消化和刷缘酶的活性；以及肠氨基酸转运蛋白mRNA水平的上调（SLC1A5和SLC6A19b，p  <.05）与TOR信号通路的激活部分相关。然而，高膳食纤维水平（NDF≥181.2 g / kg膳食）不利于营养物质的消化吸收，导致生长性能下降。因此，根据体重增加和饲料效率的二次回归分析，可以估算出生长中日粮NDF的最佳水平（日粮143.9和134.5 g / kg）和最大耐受量（日粮189.8和171.2 g / kg）草鱼。