豆油替代鱼油对中华绒螯蟹幼蟹生长、非特异性免疫和抗病力的影响

以酪蛋白和明胶为蛋白源配制5组等氮等能的实验饲料, 分别为全鱼油(F1)、25%(F2)、50%(F3)和75%(F4)豆油替代组和全豆油组(F5), 每组4个重复, 投喂初始体质量为(0.27±0.03) g的中华绒螯蟹(Eriocheir sinensis)幼蟹6周, 评价豆油替代鱼油的饲料对幼蟹生长、非特异性免疫力和抗病力的影响。结果发现, 各组幼蟹的存活率差异不显著(P>0.05); F4组幼蟹的增重率和特定生长率显著高于F1组(P<0.05), 但与其他各组差异不显著(P>0.05)。F4组幼蟹的血清酸性磷酸酶和碱性磷酸酶活性均显著高于其他各组(P<0.05), F5组最低。幼蟹的血清中超氧化物歧化酶活性以F4组最高, 显著高于F3组(P<0.05), F3和F4组均显著高于其他各组(P<0.05), 其他F1、F2和F5三组间差异不显著(P>0.05)。F1组幼蟹的血清丙二醛含量最高(P<0.05), 其余各组之间则差异不显著(P>0.05); F4组幼蟹的血清酚氧化酶活性最高, 而F5组最低(P<0.05); 各组幼蟹的溶菌酶差异不显著(P>0.05)。实验结束后, 采用嗜水气单胞菌(Aeromonas hydrophila)攻毒10 d, 发现F5组幼蟹最早出现死亡, 且该组幼蟹的累积死亡率显著高于F1和F4组(P<0.05)。结果提示, 采用豆油完全替代饲料中的鱼油对幼蟹的生长影响不显著, 但会降低其抵抗感染疾病的能力; 用75%豆油替代鱼油可在明显提高幼蟹免疫机能和抗病力的情况下获得良好的生长性能。

Effect of replacing dietary fish oil with soybean oil on growth, non- specific immune response, and resistance to Aeromonas hydrophila challenge in Chinese mitten crab, Eriocheir sinensis

Traditionally, fish oil is the main lipid source in the feed for most species in aquaculture owing to its effective supply of energy and high content of essential fatty acid. The fatty acid especially n-3 HUFA from the fish oil had also been proved to have positive effect on maintaining the immune system. However, the decline of fish oil production from wild fisheries has resulted in a supply shortage and price escalation of fish oil. Therefore, it has been a major challenge to find viable sources of oil to substitute fish oil. Among available vegetable oils, soybean oil has been widely chosen due to its availability, price and abundant content of fatty acid. In this study, we evaluated the effects of diets with different fish oil and soybean oil ratios on grouth, non-specific immune response and disease resistance in Chinese mitten crab (Eriocheir sinensis). Five isonitrogenous and isoenergetic diets were formulated in which 0% (control: F1), 25%, 50%, 75%, or 100% (F2−F5) of the fish oil was replaced with soybean oil. Juvenile crabs (mean weight 0.27±0.03 g) were assigned to one of five treatment groups (four replicates per group) and fed one of the diets for 42 d. There was no significant difference in the survival rate among the treatments (P>0.05). The weight gain was significantly higher in the F4 group than in the F1 group (P<0.05). Similarly, the crabs in the F4 group had significantly higher serum ACP (acid phosphatase), AKP (alkaline phosphatase), and serum SOD (superoxide dismutase) activities than the other treatment groups (P<0.05). F4 and F3 group were significantly higher than the other groups (P<0.05). Serum MDA (malondialdehyde) content was significantly higher in the F1 group than in the other groups, but there was no difference between the other groups (P>0.05). Serum PO (phenoloxidase) activity was higher in F4 and lower in F5 than the other groups (P<0.05). There was no difference in serum lysozyme activity among the groups (P>0.05). After the feeding experiment, the crabs were infected with Aeromonas hydrophila for 10 d. The first death was recorded in F5, and the crabs in F5 had significantly higher cumulative mortality than those in F1 and F4 (P<0.05), but there was no significant difference among the other groups (P>0.05). In conclusion, complete substitution of fish oil with soybean oil did not affect growth performance, but did reduce the ability to resist disease. Our results suggest that replacement of 75% fish oil with soybean oil in the diet of Chinese mitten crab can improve growth with little effect on disease resistance.