本试验旨在研究丁酸钠对湘云鲫蛋白质代谢及其相关基因表达的影响。试验在室内养殖系统中进行,将450尾初始体质量为(6.02±0.16) g的湘云鲫随机分为5组(每组设3个重复,每个重复30尾),分别饲喂在基础饲料中添加0(对照)、1.0、2.5、5.0和7.5 g/kg丁酸钠(30%微囊包膜丁酸钠)的等氮等能试验饲料,试验持续7周。结果表明:饲料中添加1.0~7.5 g/kg丁酸钠显著提高了湘云鲫血清总蛋白、白蛋白、球蛋白的含量(P<0.05);亦提高了血清白球比、谷草转氨酶活性和葡萄糖含量,但仅2.5和5.0 g/kg丁酸钠组的血清白球比、2.5 g/kg丁酸钠组的血清谷草转氨酶活性和5.0 g/kg丁酸钠组的血清葡萄糖含量与对照组相比达到了显著水平(P<0.05)。与对照组相比,各添加组血清游离非必需氨基酸含量有增有减,变化规律不明显。随着丁酸钠添加水平的增加,血清中其他游离必需氨基酸基本上都表现为先增加后降低,在丁酸钠添加水平为2.5 g/kg时达到最高,而唯独赖氨酸表现为持续下降。与对照组相比,1.0和2.5 g/kg丁酸钠组肠道氨肽酶N(APN)基因的相对表达量显著降低(P<0.05),2.5、5.0和7.5丁酸钠组肠道谷氨酸脱氢酶(GDH)基因的相对表达量显著升高(P<0.05)。上述结果表明,饲料中添加适量的丁酸钠可提高湘云鲫的蛋白质代谢水平及其相关基因的表达,结合生长指标和生产成本,推荐添加剂量为2.5 g/kg。

A 7-week feeding experiment was conducted to evaluate the effects of dietary sodium butyrate on protein metabolism and its related gene expression of triploid crucian carp (Carassius auratus tripl). A total of 450 triploid crucian carp with an average body weight of (6.02±0.16) g were randomly assigned to 5 groups with 3 replicates per group and 30 fish per replicate. Five isonitrogen and isocaloric experimental diets were formulated by adding 0 (control), 1.0, 2.5, 5.0 and 7.5 g/kg sodium butyrate (30% microcapsule coated sodium butyrate) to the basal diet, respectively. The fish in the 5 groups were randomly fed one of five experimental diets. The results showed that the supplementation of 1.0 to 7.5 g/kg sodium butyrate significantly improved the contents of serum total protein (TP), albumin (ALB), and globulin(GLB) (P<0.05), and it also improved the serum ALB/GLB, aspartate aminotransferase (AST) activity and glucose (GLU) content, but only the serum ALB/GLB in 2.5 and 5.0 g/kg sodium butyrate groups, serum AST activity in 2.5 g/kg sodium butyrate group, and serum GLU content in 5.0 g/kg sodium butyrate group reached a significance level compared with the control group (P<0.05). Compared with the control group, the contents of serum non-essential free amino acid were sometimes increased and sometimes decreased, and the change was not evident. Only the content of serum lysine was decreased continuelly, the serum other essential free amino acid contents were essentially firstly increased and then increased with the sodium butyrate supplemental level increasing, and had the highest values when the sodium butyrate supplemental level was 2.5 g/kg. Compared with the control group, the intestinal aminopeptidase N (APN) gene relative expression level in 1.0 and 2.5 g/kg sodium butyrate groups was significantly decreased (P<0.05), while the intestinal glutamate dehydrogenase (GDH) gene relative expression level in 2.5, 5.0 and 7.5 g/kg sodium butyrate groups was significantly increased (P<0.05). The results indicate that optimal supplemental level of sodium butyrate can increase the protein metabolism level and its related gene expression of triploid crucian carp, and the recommended supplemental level of sodium butyrate is 2.5 g/kg which is based on the growth indices and production costs.