饲料维生素A对美国红鱼生长和免疫的影响

本试验旨在研究饲料维生素A对美国红鱼生长(增重率、特定生长率、存活率和饲料效率)和免疫反应相关指标(血清中溶菌酶活性、超氧化物歧化酶活性和总补体活性)的影响.采用单因子试验设计,将300尾平均体重为(151.46±8.18)g的美国红鱼随机分为5个处理,每个处理设3个重复,每个重复20尾,分别饲喂5种不同VA水平(30、4 166、8 533、18 532、33 263 IU/kg)的等氮等能饲料,进行为期8周的生长试验.结果表明:饲料中VA水平为30 IU/kg时其增重率、饲料效率、特定生长率、成活率均显著低于4 166、8 533、18 532 IU/kg组(P<0.05),VA水平为33 263 IU/kg时各指标有所降低.其中饲料效率和特定生长率显著低于4 166、8 533、18 532 IU/kg组(P<0.05);VA水平为30 IU/kg时血清溶菌酶活性,SOD活性和总补体活性显著低于其他组(P<0.05),VA水平在18 532 IU/kg时血清溶菌酶活性达到最高值,其次为33 263、8 533、4 166 IU/kg组;VA水平在8 533 IU/kg时血清SOD和总补体活性达到最高值,并显著高于4 166、18 532、33 263IU/kg组(P<0.05).综上所述,饲料中适宜VA水平能显著促进美国红鱼生长、提高相关免疫力,且饲料VA水平为8 533 IU/kg时对美国红鱼生长和免疫相关指标影响较显著.

Effects of Dietary Vitamin A Levels on Growth and Immune Response of Red Drum (Sciaenops Ocellatus L.)

A single factor design was conducted to study the effects of dietary vitamin A on growth (weight gain rate, specific growth rate, survival rate and feed efficiency ratio) and immune response (lysozyme activity, superoxide dismutase (SOD) activity and total complement activity) of red drum (Sciaenops Ocellatus L. ). Three hundred fish with body weights of (151.46±8.18) g were randomly allocated to 5 treatments with 3 replicates each and 20 fish in each replicate. Six treat-ments were fed with 5 iso-nitrogenous and iso-energetic diets containing 5 levels of vitamin A (30, 4 166, 8 533, 18 532 and 33 263 IU/kg diet, respectively), and the experiment lasted for 8 weeks. The results showed that, 30 IU/kg treatment had the lowest weight gain rate, specific growth rate, survival rate and feed efficiency ratio, and lower than those in 4 166,8 533,18 532 IU/kg treatments significantly (P<0.05). Specific growth rate and feed efficiency ratio in 33 263 IU/kg treatment were lower than those in 4 166, 8 533, 18 532 IU/kg treatments significantly (P<0.05). The lysozyme activity, SOD activity and total complement activity in 30 IU/kg treatment were significantly lower than those in other treatments (P<0.05). The maximal level of lysozyme activity was in 18 532 IU/kg treatment, followed by 8 533, 4 166, 33 263 IU/kg treatments. The maximal level of SOD activity and total complement activity was in 8 533 IU/kg treatment, and higher than those in 4 156, 18 532, 33 263 IU/kg treatments significantly (P<0.05). In conclusion, the growth performance and im-mune response of red drum could be improved significantly by the proper dietary vitamin A level, and optimum level of vita-min A to improve growth performance and immune response of red drum was 8 533 IU/kg.