饲料维生素C水平对吉富罗非鱼生长性能、肌肉品质和抗氧化功能的影响

以维生素C多聚磷酸酯为维生素C(VC)源,评价了饲料VC水平对吉富罗非鱼(Oreochromis niloticus)生长、肌肉品质和抗氧化功能的影响。在基础饲料中分别添加0、60、300和1 500 mg/kg的VC(分别记为C 0、C 60、C300和C 1500组)配制成4种实验饲料,投喂初始体质量为(77.07±2.24)g的吉富罗非鱼56 d,实验分为4组,每组3个重复,每个重复20尾鱼。结果表明,饲料中添加VC可以显著提高吉富罗非鱼的增重率、特定生长率和成活率(P0.05),但3个添加组之间无显著差异(P0.05);各实验组罗非鱼肌肉的粗蛋白、粗脂肪和粗灰分含量不受饲料VC添加水平的影响(P0.05),罗非鱼肌肉的水分含量以C 1500组最低,显著低于其余3组(P0.05);C 300组罗非鱼肌肉的弹性和咀嚼性显著高于C 0组(P0.05);C 1500组的肌肉硬度、凝聚性、弹性、黏性、咀嚼性均显著高于C 0组(P0.05),各组的肌肉回复性无显著差异(P0.05);VC添加组的罗非鱼血清和肌肉的超氧化物歧化酶(SOD)活性均显著高于C 0组(P0.05),血清过氧化氢酶(CAT)活性以C 300组最高,显著高于C 0组(P0.05),肌肉CAT活性有增高趋势但未出现显著差异(P0.05),3个VC添加组的血清丙二醛(MDA)含量均显著低于C 0组(P0.05),C1500组的肌肉MDA含量显著低于C 0组(P0.05)。上述结果表明,饲料中添加适量VC(有效含量282 mg/kg)能提高吉富罗非鱼的生长性能,改善其肌肉品质,增强机体抗氧化功能。

Effect of dietary vitamin C on growth performance, flesh quality and antioxidant function in genetically improved farmed tilapia

Vitamin C (VC) is an essential water-soluble antioxidant vitamin involved in normal physiological functions in fish. It plays important roles in growth, collagen synthesis, iron metabolism, and immune function. VC has also been found to play an active role in reducing the effects of pre-slaughter stress and in improving the meat quality of livestock and poultry. However, little information is available on its effect on flesh quality in the genetically improved farmed tilapia (GIFT), Oreochromis niloticus. Hence, this study was conducted to investigate the effects of dietary supplemental VC on growth, flesh quality and antioxidant function in GIFT. In total, 240 fish (mean initial body weight, 77.07±2.24 g) were assigned to four groups (20 fish per replicate, triplicate experiments). The fish were fed four experimental diets supplemented with different levels of VC: 0, 60, 300 and 1 500 mg/kg (C 0, C 60, C 300 and C 1500, respectively), supplied as L-ascorbyl-2-phosphate for 56 d. After the feeding trial, fish fed with the C 0 diet had significantly lower weight gains, specific growth and survival rates than those fed on diets supplemented with VC (P<0.05), but no significant differences were observed among fish fed on diets supplemented with VC (P>0.05). Dietary VC supplementation had no significant effect on the protein, lipid and ash contents of fish muscle (P>0.05). However, the moisture content of fish muscle in the C 1500 group was significantly lower than those in the other three groups (P<0.05). Fish fed the C 300 diet had significantly higher springiness and chewiness than those fed on the C 0 diet (P<0.05). The values for hardness, cohesiveness, springiness, gumminess, and chewiness of the fish fed on the C 1500 diet were significantly higher than those of fish fed the C 0 diet (P<0.05). However, muscle resilience was not significantly affected by dietary VC levels (P>0.05). VC supplementation increased the superoxide dismutase activity in the serum and muscle tissue of tilapia significantly (P<0.05). Fish fed with the C 300 diet had the highest serum peroxidase activity, and this activity was significantly higher than that of the C 0 group (P<0.05). Compared with the C 0 group, peroxidase activity in muscle increased but was not significantly different from the VC-supplemented groups (P>0.05). The malonic aldehyde contents in serum and muscle decreased significantly in the VC-supplemented groups and the C 1500 group, respectively (P<0.05). These results suggest that dietary VC supplementation (at an effective level of 282 mg/kg) may improve the growth performance, meat quality and antioxidant function in GIFT to get better effect on quality and antioxidant function, it is recommended to supplement 1 500 mg/kg VC (at an effective level of 1 437 mg/kg) in the diet of GIGT.