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试验旨在研究苏氨酸对幼年草鱼生长性能、生化指标和肠道形态的影响。饲喂6种含有络氨酸、明胶和不同水平的苏氨酸(0.73、1.03、1.33、1.63、1.93、2.23 g·100 g-1干物质)的等能、等氮的半精制饲料。每组3个重复中,每个重复30尾鱼(4.02±0.004 g),饲喂10周。记录添加苏氨酸幼龄草鱼的最高增重(WG,%)、最终体重(FBW,g)及比生长速率(SGR)。SGR的二次多项式回归分析表明,苏氨酸的最佳需求量是1.37%,对应日粮中蛋白质3.61%。日粮中苏氨酸的水平显著影响草鱼整体蛋白、肌蛋白、天冬氨酸转氨酶和胆固醇(P<0.05)。且苏氨酸的沉积显著受日粮中苏氨酸水平的影响(P<0.05)。饲喂苏氨酸0.73%、1.03%的日粮,草鱼的肠绒毛脱落、扭曲、且严重融合,前肠绒毛高度和浆膜层的厚度下降。研究表明,日粮中苏氨酸的水平不仅影响草鱼生长、采食量和体蛋白的合成,同时也影响前肠发育和完整性。
The aim of this experiment was to investigate the effects of threonine on the growth performance, biochemical parameters and intestinal morphology of young grass carp. Six isoforms of equal energy, nitrogen, and other semi-refined feeds containing tyrosine, gelatin and different levels of threonine (0.73, 1.03, 1.33, 1.63, 1.93 and 2.23 g • 100 g -1 dry matter) were fed. Thirty fish (4.02 ± 0.004 g) were repeated for each of three replicates and fed for 10 weeks. The highest weight gain (WG,%), final body weight (FBW, g) and specific growth rate (SGR) of young threonine fed grass carp were recorded. Quadratic polynomial regression analysis of SGR showed that the best requirement for threonine was 1.37%, corresponding to 3.61% protein in the diet. Dietary threonine levels significantly affected whole grass carp protein, muscle protein, aspartate aminotransferase, and cholesterol (P <0.05). Threonine deposition was significantly affected by threonine levels in the diet (P <0.05). Feeding threonine 0.73%, 1.03% of the diet, grass carp intestinal villi shed, distorted, and severe integration, villus height and serosal thickness decreased. Studies have shown that dietary threonine levels affect not only grass carp growth, feed intake, and body protein synthesis but also foregut development and integrity.