饲料中铁对美国红鱼(Sciaenops ocellatus)生长和免疫的影响

EFFECTS OF DIETARY IRON ON GROWTH AND IMMUNE RESPONSE OF RED DRUM SCIAENOPS OCELLATUS

采用单因子实验设计方法,进行了饲料中添加铁对美国红鱼生长(增重率、存活率、特定生长率和饲料效率)、免疫反应(血清溶菌酶活性、总补体活性和超氧化物歧化酶活性(Superoxide dismutase,SOD)和组织中铁积累量影响的研究。结果表明,各饲料组美国红鱼的成活率(93.33%-95.00%)无显著性差异(P>0.05);饲料铁含量在327.2、368.1mg/kg时饲料效率显著高于285.3、303.5、443.7mg/kg组(P<0.05);随着饲料中铁含量从285.3mg/kg增加到327.2mg/kg,美国红鱼的增重率和特定生长率显著升高(P<0.05),而饲料中铁含量达到443.7mg/kg之后,其增重率和特定生长率显著下降;以特定生长率为指标,通过回归拟合分析美国红鱼最佳生长性能的饲料铁含量为330mg/kg左右。各饲料组肌肉中铁积累量无显著性差异(P>0.05);随着饲料中铁含量从285.3mg/kg增加到443.7mg/kg,美国红鱼肝脏中铁积累量显著增加(P<0.05)。饲料铁含量在368.1mg/kg时血清溶菌酶活性达到最高值,并显著高于285.3、303.5、327.2mg/kg组(P<0.05);饲料铁含量在327.2、368.1、443.7mg/kg时血清总补体活性显著高于285.3、303.5mg/kg组(P<0.05);饲料铁含量在327.2、368.1mg/kg时血清SOD活性较高,但各饲料组之间无显著性差异(P>0.05)。综上所述,美国红鱼生长和免疫的饲料铁适宜含量为368.1mg/kg左右。

An experiment was conducted to study the effects of dietary iron on growth （weight rate, feed efficiency ratio, specific growth rate （SGR） and survival rate）, immune response [lysozyme activity, total complement activity and superoxide dismutase （SOD） activity] and body distribution of iron concentration of red drum （Sciaenops ocellatus Linnaeus）. Five iso-nitrogenous and iso-energetic diets were formulated to contain 285.3, 303.5,327.2, 368.1 and 443.7 mg Fe per kg diet, supplied as FeSO4 · 7H2O, and fed in 15 floating netcages （1.5 × 1.0 × 1.0m） to 20 fish [initial weight： （173.41± 4.85）g] twice a day （09：30 and 16：30） for 8 weeks, the water temperature was set from 26.5 to 32.5℃, salinity from 28 to 29 and dissolved oxygen was approximately 6mg/L during the experimental period. Results indicate that no significant differences in survival rate （93.33%-95.00%） were found among dietary treatments （P〉0.05）; feed efficiency ratio in 327.2 and 368.1 mg/kg treatments were significantly higher than those in 285.3,303.5 and 443.7mg/kg treatments （P〈0.05）. Weight rate and specific growth rate in 327.2 and 368. lmg/kg treatment were higher significantly those in other treatments （P〈0.05）, regression curve analysis shows that the optimum dietary iron requirement for red drum, using SGR as response criteria, was 330mg/kg diet. No significant differences in iron concentration of muscle were found among dietary treatments （P〉0.05）. Iron concentration in liver increased significantly with increasing dietary iron from 285.3 to 443.7mg/kg （P〈0.05）. The maximal level of serum lysozyme activity was in 368. lmg/kg treatment, significantly higher than those in other treatments （P〈0.05）. Serum total complement activity in 327.2, 368.1 and 443.7mg/kg treatments was significantly higher than those in 285.3 and 327.2mg/kg treatments （P〈0.05）. Serum SOD activity in 327.2 and 368.1mg/kg treatments were higher, but no significant differences in serum SOD activity were found among dietary treatments （P〉0.05）. Based on the information above, the optimal dietary iron content for optimum growth performance and immune response in red drum is about 368.1mg/kg of dietary iron.