不同饲料类型和放养密度对乌鳢生长特性及营养品质的影响

为了解不同饲料类型和放养密度对体质量(136.62±5.34)g的乌鳢Channa argus生长及营养品质的影响,采用围隔养殖试验法,研究了3种放养密度(15 000、30 000、45 000 ind./hm2)和2种饲料类型(冰鲜鱼和配合饲料)对乌鳢生长性能、生物学性状和肌肉营养成分的影响。结果表明:冰鲜鱼投喂组乌鳢的增重率、特定生长率显著高于配合饲料投喂组(P0.05),饵料系数显著低于配合饲料投喂组(P0.05),成活率无显著性影响(P0.05),放养密度对乌鳢增重率、特定生长率、饵料系数和成活率均无显著性影响(P0.05);饲料投喂组乌鳢的肥满度、肝体指数和脏体指数显著高于冰鲜鱼投喂组(P0.05),放养密度对其无显著性影响(P0.05),但饵料类型与放养密度二者的交互作用对脏体指数影响显著(P0.05),对肥满度和肝体指数无显著性影响(P0.05);饲料类型、放养密度对乌鳢肌肉的水分、灰分、粗蛋白质和粗脂肪无显著性影响(P0.05);各试验组乌鳢肌肉中的18种氨基酸含量除脯氨酸外无显著性差异(P0.05);氨基酸评价表明,投喂配合饲料的乌鳢肌肉蛋白质品质优于投喂冰鲜鱼的乌鳢,且以低密度养殖时最佳;脂肪酸分析表明,投喂配合饲料的乌鳢饱和脂肪酸(SFA)含量显著高于投喂冰鲜鱼(P0.05),但二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)等9种多不饱和脂肪酸(PUFA)含量显著低于投喂冰鲜鱼组(P0.05);投喂冰鲜鱼相对于投喂配合饲料,可提高养殖乌鳢生长性能,改善生物学性状,降低肝体指数、脏体指数和肥满度,对肌肉氨基酸总量、必需氨基酸总量无显著性影响(P0.05);3种放养密度对乌鳢生长性能和营养成分无显著性影响(P0.05)。研究表明,配制饲料时可参考冰鲜鱼的营养成分,降低碳水化合物含量,增加不饱和脂肪酸添加量,以提升养殖乌鳢营养品质。

Comparison of growth performances and nutritional quality of muscle in snakehead Channa argus fed different diets at different stocking densities

The growth performances, biological traits and nutritional quality of muscle were studied in snakehead Channa argus with body weight of(136. 62±5. 34)g reared in an enclosure and fed fresh frozen trash fish(TF) and formulated diet (FF) at three stocking densities of 15000, 30000 and 45000 ind. /hm2 with triplication from the beginning of September 7 , 2015 to the end of November 2 , 2015 by biochemical method in order to provide refer-ence to optimize feed formula and culture pattern. It was found that there were significantly higher weight growth rate and specific growth rate and significantly lower food conversion ratio in the fish fed FT than in the fish fed FF ( P<0 . 05 ) , without significant difference in survival rates of the fish fed different diets and without significant differences in weight growth rate and specific growth rate and food conversion ratio in different stocking density groups (P>0. 05). The fish fed TF had significantly lower hepatosomatic index, viscerosomatic index and condition factor than the fish fed FF did at the same stocking density ( P<0 . 05 ) , without significant differences in different stocking density groups (P>0. 05). There was no significant difference in contents of ash, crude fat, and crude protein containing 18 kinds of amino acids except for proline in different groups ( P>0 . 05 ) . The protein quality of the fish fed FF was superior to the fish fed TF by EAAI method, especially at low stocking density. Fatty acid anal-ysis showed that the fish fed FF had significantly higher percentage of saturated fatty acids ( SFA) in muscle than the fish fed TF did(P<0. 05), with significantly higher percentage of nine polyunsaturated fatty acids (PUFA)such as EPA and DHA than the fish fed FF(P<0. 05). It is recommended that formulated diet be optimized by reduction in dietary carbohydrates content and improvement of polyunsaturated fatty acid composition and content based on nutritional property of TF, in order to promote healthy snakehead farming.