叶黄素对七彩神仙鱼生长和体色的影响

Effect of dietary xanthophyll on the growth and body color of discus fish(Symphysodon aequifasciata)

为研究叶黄素对七彩神仙鱼体色和生长的影响,在"牛心汉堡"饲料中分别添加0、50、100、200、300和400 mg/kg叶黄素,饲喂初始平均体质量(10.3±0.3)g的七彩神仙鱼8周。结果显示,添加叶黄素50~200 mg/kg,对鱼体增重率无显著影响,但添加量达200 mg/kg后,饲料系数显著增大,添加量达300 mg/kg后,增重率显著降低。在养殖4周、8周时,鱼体皮肤亮度(L*)无显著变化,皮肤黄度(b*)和叶黄素含量随叶黄素添加量增加而显著升高;8周时,各叶黄素添加组的皮肤b*值和叶黄素含量显著高于4周时,当叶黄素添加量达300 mg/kg后,皮肤b*值(4周、8周)和全鱼叶黄素含量(8周)趋于稳定;4周时,各处理组间的皮肤红度(a*)无显著差异;8周时,当叶黄素添加量达100 mg/kg后,皮肤a*值显著降低;饲料中添加300 mg/kg叶黄素显著提高了七彩神仙鱼肝脏总抗氧化能力。研究表明,在饲料中添加叶黄素可有效改善七彩神仙鱼体表黄色,提高肝脏总抗氧化能力,但高添加量的叶黄素会降低鱼体生长性能,七彩神仙鱼饲料中的叶黄素添加量建议为200~300 mg/kg。

To assess the effects of dietary xanthophyll on the growth and body color of discus fish（Symphysodon sp.）, xanthophyll was added into the basal diet（beef heart hamburg） with the levels of 0, 50, 100, 200, 300 and 400mg/kg, respectively. The six experimental diets were fed to discus fish with an initial body weight of （10.3±0.3） g for 8 weeks. The results showed that the supplementation of 50–200 mg/kg xanthophyll had no significant effects on the weight gain rate, but the feed coefficient ratio significantly increased and the weight gain rate significantly decreased when the xanthophyll supplementation reached 200 or 300 mg/kg respectively. After 4 or 8 weeks＇ feeding, the skin lightness（L^＊） showed no significant differences among groups, but the skin yellowness（b^＊）increased with the increase of dietary xanthophyll. The b^＊ value and xanthophyll content in skin of all xanthophyllsupplemented groups in the 8^th week were higher than those in the 4^th week. The b^＊ values in the 4^th week and 8^th week, and the xanthophyll content in whole fish in the 8^th week remained relatively stable when the xanthophyll supplementation reached 300 mg/kg. In the 4^th week, the skin redness（a^＊） showed no significant difference among groups, but in the 8^th week, the a^＊ values significantly decreased when the xanthophyll supplementation reached 100 mg/kg. The hepatic total antioxidant capacity was significantly strengthened by the supplementation of 300 or 400 mg/kg xanthophyll. The above results showed that dietary xanthophyll could effectively improve the yellowness of the skin and strengthen the hepatic total antioxidant capacity of discus fish, but the high inclusion of xanthophyll reduced the growth of the fish. The supplementation level of xanthophyll was suggested to be 200–300 mg/kg.