氯化钴在大菱鲆饲料中的安全性评价

Safety evaluation of dietary cobalt dichloride in turbot

通过研究饲料中的氯化钴对大菱鲆幼鱼的存活、生长性能、血清生理生化指标、抗氧化酶活力、消化酶活力、血清和肝脏中VB12含量、肌肉和肝脏中钴的残留量、肝脏和肠道组织结构的影响来评估氯化钴在海水鱼饲料中的安全性。通过在基础饲料中添加氯化钴制剂来配制4种具有不同氯化钴含量(0、8、40及80 mg/kg,不计结晶水重量)的等氮等能的实验饲料,每个饲料处理设6个重复,每个重复养殖30尾大菱鲆;养殖实验为期10周。实验结果表明:饲料中添加氯化钴对试验鱼的存活没有显著影响(P>0.05),但饲料中80 mg/kg的氯化钴显著降低了大菱鲆的特定生长率、终末体重、摄食率、肝体比和脏体比(P<0.05);饲料中高剂量氯化钴(40和80 mg/kg)显著降低了大菱鲆血清过氧化氢酶、谷草转氨酶和碱性磷酸酶活力以及大菱鲆胃淀粉酶和胰蛋白酶活力(P<0.05);大菱鲆的血糖含量、血清和肝脏中VB12含量、肝脏和肌肉中钴的残留量均随饲料中钴的添加量增加而显著升高(P<0.05);饲料中添加氯化钴对大菱鲆的肠道组织结构没有产生明显影响,但饲料中添加40和80 mg/kg的氯化钴增宽了肝脏肝血窦。研究结果表明:实验条件下,氯化钴在大菱鲆饲料中的添加量8 mg/kg是安全的。

The effects of dietary cobalt dichloride on survival, growth performance, haematological parameters, antioxidases activities, digestive enzymes activities, Vm contents in serum and liver, tissue cobalt residues, and intestinal and liver morphology of turbot （Scophthalmus maximus L. ） were studied for safe utilization of cobalt dichloride in fish feed. The experimental dietary cobalt dichloride inclusion level was 0, 8, 40 and 80 mg/kg respectively. Six replicates of 30 fish were used for each treatment group. No mortality was observed during the 10-week feeding trial. Growth performances of fish were not significantly affected by dietary cobalt dichloride supplementation from 0 to 40 mg/kg （P 〉 0.05 ）, however, 80 mg/kg dietary cobalt dichloride significantly decreased the final weight, specific growth rate, final weight, feed intake, hepatosomatic index, and viscerosomatic index （P 〈 0.05 ）. Supplementation of 40 and 80 mg/kg cobalt dichloride in diet decreased activities of catalase, aspartate transferase, and alkaline phosphatase in fish （P 〈 0.05 ）. The activity of stomach amylase was significantly decreased by dietary supplementation of 40 and 80 mg/kg cobalt dichloride （ P 〈 0.05 ）, while dietary supplementation of 40 mg/kg cobalt dichloride significantly decreased the activity of trypsin （ P 〈 0.05 ）. With increasing level of dietary cobalt dichloride, the glucose and VB12 content in serum and liver and the cobalt residue in liver and muscle increased significantly （P 〈 0.05）. No lesion or damage was found in intestinal structures of fish from all treatments. However, 40 and 80 mg/kg dietary cobalt dichloride impaired the liver tissue and widened the hepatic sinusoid. The present results proved that 8 mg/kg cobalt dichloride was safe as additive in fish feed.