胰酶对大口黑鲈幼鱼生长、肝脏与肠道健康的影响

PANCREATIN ON GROWTH PERFORMANCE, LIVER AND INTESTINAL HEALTH OF JUVENILE LARGEMOUTH BASS (MICROPTERUS SALMOIDES)

  • 摘要: 为评价胰酶对大口黑鲈(Micropterus salmoides)幼鱼生长、肝脏与肠道健康的影响, 用棉籽饼粕(Cottonseed meal, CSM)替代40%的鱼粉蛋白后, 分别以250、500、750、1000和1250 mg/kg水平分别添加胰酶, 制作成等氮等脂的五组实验饲料, 同时分别以正常商品饲料和CSM替代(不添加胰酶)组为负对照组及正对照组, 饲喂大口黑鲈幼鱼 初始体质量(8.00±0.50) g 70d。结果显示, CSM替代鱼粉后, 大口黑鲈幼鱼饲料利用率、生长及消化性能显著下降(P<0.05), 肝脏与肠道健康受到显著损伤(P<0.05)。添加250—750 mg/kg胰酶后, 大口黑鲈幼鱼终末体质量(FBW)、增重率(WGR)、特定生长率(SGR)及成活率(SR)显著提高(P<0.05), 饲料系数(FCR)显著降低(P<0.05); 750 mg/kg时, 肥满度(CF)显著升高(P<0.05), 脏体比(VSI)和肝体比(HSI)显著性降低(P<0.05), 粗蛋白含量显著提高(P<0.05); 250—1 000 mg/kg时, 胃、前肠及肝中蛋白酶、淀粉酶及脂肪酶活性显著提高(P<0.05); 750 mg/kg时, 干物质、粗蛋白质及粗纤维表观消化率最高, 粪便中氮磷含量最低; 250—750 mg/kg时, 丙二醛(MDA)显著下降(P<0.05), 过氧化氢酶(CAT)、总超氧化物歧化酶(T-SOD)、总抗氧化能力(T-AOC)、谷草转氨酶(AST)及谷丙转氨酶(ALT)活性显著上升(P<0.05); 750 mg/kg时, 肝脏sod、cat基因相对表达量显著上调(P<0.05), 抗炎因子IL-10、TGF-β 的相对表达量最高, 而促炎因子IL-1β、IL-8和TNF-a的相对表达量最低, 肠道紧密连接蛋白 (occludinzo-1 和claudin-1) 基因相对表达量显著上调(P<0.05), 而血清中二胺氧化酶(DAO)活性、D-乳酸(D-Lac)和内毒素(ET)含量显著降低(P<0.05)。研究表明, CSM替代40%的鱼粉蛋白会对大口黑鲈幼鱼生长和健康产生显著影响, 胰酶适量添加时, 可显著提高大口黑鲈幼鱼生长性能、消化酶活性及表观消化率, 同时, 可显著改善肝脏和肠道健康(750 mg/kg时综合效果最好)。因此, 胰酶可作为大口黑鲈幼鱼饲料的优质添加剂。

     

    Abstract: In order to evaluate the effects of different levels of pancreatin (from porcine pancreas) on the growth, digestion, liver and intestinal health of juvenile largemouth bass (Micropterus salmoides), a study was conducted where 40% of fish meal protein was replaced with cottonseed meal. Pancreatin was added at levels of 250, 500, 750, 1000, and 1250 mg/kg levels (TG-250, TG-500, TG-750, TG-1000 and TG-1250, respectively), ensuring isonitrogenous and isolipidous conditions. A normal commercial diet served as the negative control group (NCG), and the cottonseed meal replacement (without pancreatin) group served as the positive control group (PCG). The juvenile largemouth bass initial body weight (8.00±0.50) g was fed for 70 days. The results showed that replacing fish meal with cottonseed meal decreased feed utilization rate, growth, and digestive performance (P<0.05), and adversely affected liver and intestinal health (P<0.05). However, adding pancreatin significantly increased final body weight (FBW), weight gain rate (WGR), specific growth rate (SGR), and survival rate (SR), and decreased the feed coefficient (P<0.05) in the range of 250—750 mg/kg. At 750 mg/kg, the condition factor (CF) increased (P<0.05), while the visceral index (VSI) and hepatosomatic index (HSI) decreased (P<0.05), and crude protein content increased (P<0.05). The activities of protease, amylase, and lipase in the stomach, foregut, and liver increased in the range of 250—1000 mg/kg (P<0.05). At 750 mg/kg pancreatin, the apparent digestibility of dry matter, crude protein, and crude fiber was the highest, and the nitrogen and phosphorus content in feces was the lowest. In the range of 250—750 mg/kg, malondialdehyde (MDA) levels decreased (P<0.05), while catalase (CAT), total superoxide dismutase (T-SOD), total antioxidant capacity (T-AOC), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) activities increased (P<0.05). At 750 mg/kg, the relative expression of sod and cat gene in liver was up-regulated (P<0.05), the relative expression of anti-inflammatory factors IL-10 and TGF-β was the highest, while the relative expression of pro-inflammatory factors IL-1β, IL-8, and TNF-a was the lowest. Additionally, the expressions of occludin, zo-1, and claudin-1 in the intestinal tract was up-regulated (P<0.05), and the activities of diamine oxidase (DAO), D-lactic acid (D-Lac), and endotoxin (ET) in serum were decreased (P<0.05). In conclusion, the replacement of 40% fish meal protein by cottonseed meal had a significant effect on the growth and health of juvenile largemouth bass. The growth performance, digestive enzyme activity, and apparent digestibility could be significantly improved by adding appropriate amount of pancreatin (750 mg/kg), as well as the liver and intestinal health. Therefore, pancreatin can be used as a high-quality additive for juvenile largemouth bass feed.

     

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