壳聚糖对饲料镉胁迫下吉富罗非鱼生长、肠道消化酶活性、血清生化指标及镉残留的影响

Effect of chitosan on growth performance, intestinal digestive enzymes activities, serum biochemical indexes and cadmium residue of genetic improvement of farmed tilapia(GIFT, Oreochromis Niloticus)under dietary cadmium stress

采用单因子随机区组试验设计方法,以平均体重为(10.69±0.55)g的吉富罗非鱼幼鱼为试验对象,在镉水平为50 mg/kg的吉富罗非鱼饲料中添加0.5%、1.0%和1.5%的壳聚糖饲喂7周,研究壳聚糖减轻饲料镉对吉富罗非鱼亚慢性毒性的效果。结果显示:与未添加壳聚糖组相比,添加壳聚糖可显著提高饲料镉胁迫下吉富罗非鱼的增重率和特定生长率(P<0.05),且随着饲料中壳聚糖水平的增加逐渐升高;肠道消化酶的活性随着饲料中壳聚糖水平的增加而升高,1.5%壳聚糖添加组淀粉酶活性、1.0%壳聚糖添加组和1.5%壳聚糖添加组的脂肪酶活性以及各壳聚糖添加组的蛋白酶活性均显著升高(P<0.05);降低了血液尿素氮、谷丙转氨酶和谷草转氨酶水平;随着壳聚糖的添加水平升高,肠道、肌肉和养殖水体中镉水平显著降低(P<0.05),粪便镉水平显著升高(P<0.05)。试验结果表明,壳聚糖对饲料镉致罗非鱼亚慢性毒性的缓解效果随其在饲料中添加水平的升高而增强,并在很大程度上通过发挥吸附作用减轻了饲料镉对罗非鱼的毒性。

A 7- week feeding trial with singlefactor randomized block design was conductedto investigate the effects of chitosan(CTS) onsubchronic toxicity of dietary cadmium(Cd) togenetic improvement of farmed tilapia(Oreochro-mis niloticus). The fish with an initial averageweight of(10.69±0.55) g were randomly divided into four treatment groups. The chitosan levels in the four groups with 50 mg/kg dietary cadmium were 0.0%, 0.5%, 1.0% and 1.5%, respectively. The weight gain rate and specific growth rate in CTS supplementation groups were significantly higher than those in Cd group without CTS supplementation(P<0.05), these growth performance parameters were improved with the increasing CTS supplementation level. The intestinal digestive enzymes activities were ameliorated by CTS supplementation. The activities of amylase in 1.5% CTS supplementation group, lipase in 1.0% and 1.5%CTS supplementation groups and protease in all CTS supplementation groups were significantly higher than those in Cd group. Compared with Cd group, Cd levels in intestine, muscle and farming water of CTS supplementation groups were significantly decreased(P<0.05), Cd levels in feces of CTS supplementation groups were significantly increased(P<0.05). The results suggested that the toxicity of dietary Cd on GIFT tilapia might be alleviated by supplementation with CTS in diet. The adsorption by CTS in fish intestinal tract might play an important role on alleviating the toxicity of dietary Cd.