Six iso-nitrogenous and iso-lipidic experimental diets were formulated to evaluate the effects of Saccharomyces cerevisiae extracts, as part of a low fishmeal diet with a complex plant protein source, on the orange-spotted grouper (Epinephelus coioides). In positive control group, fishmeal was the only protein source (FM). The negative control group (Y0) was fed low amounts of fishmeal, and plant protein was used as the protein source. The other diets were supplemented with Saccharomyces cerevisiae extract: 1 g/kg (Y1), 2 g/kg (Y2), 5 g/kg (Y5), and 10 g/kg (Y10). The Epinephelus coioides were divided into six groups, with three replicates per group and 30 groupers per replicate. The experiment lasted for 56 days. The results showed that there was no significant difference in weight gain rate and specific growth rate of FM, Y0 and Y2 groups (P > 0.05). In foregut, mucosal folds length in Y2 group was significantly greater than that in Y0, Y1 and Y10 groups (P < 0.05). The muscle thicknesses of foregut in Y2 and Y5 groups were significantly higher than those in other groups (P < 0.05). The muscle thicknesses of midgut and hindgut in Y2 group were significantly higher than those in Y0 group (P < 0.05). IL-1β and TNF-α in Y1 group were significantly downregulated compared with Y0 group (P < 0.05). After Vibrio harveyi challenge, survival rate in Y1 and Y10 groups was significantly greater than that in Y0 group (P < 0.05). These results indicated that compared with the negative control group, the addition of 2 g/kg S. cerevisiae extract could increase the mucosal folds length of the foregut, and the muscle thickness of the entire intestine, and maintain the growth similar to that of the positive control group. Adding S. cerevisiae extract to feed may improve the immune capacity of E. coioides, but the improvement was not obvious under the challenge of V. harveyi.

配制了六种等氮和等脂实验日粮，以评估酿酒酵母提取物作为低鱼粉日粮中具有复杂植物蛋白源的一部分对橙斑石斑鱼（Epinephelus coioides）的影响。在阳性对照组中，鱼粉是唯一的蛋白质来源（FM）。阴性对照组（Y0）饲喂少量鱼粉，并使用植物蛋白作为蛋白质来源。其他饮食中还添加了酿酒酵母提取物：1 g / kg（Y1），2 g / kg（Y2），5 g / kg（Y5）和10 g / kg（Y10）。在斜带石斑鱼分为六组，每组三个重复，每个重复30个石斑鱼。实验持续了56天。结果表明，FM，Y0和Y2组的增重率和比生长率无显着差异（P > 0.05）。在前肠中，Y2组的粘膜褶皱长度明显大于Y0，Y1和Y10组（P <0.05）。Y2和Y5组前肠的肌肉厚度显着高于其他组（P <0.05）。Y2组中肠和后肠的肌肉厚度明显高于Y0组（P <0.05）。IL-1β和TNF-α与Y0组相比，Y1组中的PPAR显着下调（P <0.05）。后哈氏弧菌的挑战，在Y1存活率和Y10组明显高于Y0组（显著更大P <0.05）。这些结果表明，与阴性对照组相比，添加2 g / kg啤酒酵母提取物可以增加前肠的粘膜褶皱长度和整个肠的肌肉厚度，并保持与正常对照组相似的生长。阳性对照组。在饲料中添加酿酒酵母提取物可以提高大肠杆菌的免疫能力，但在哈维弧菌的挑战下效果并不明显。