两种油脂水平下DHA强化对饥饿鲤体重及脂代谢的影响

饥饿是鱼类无法有效获取食物从而使机体呈现能量匮乏的特殊时期, DHA (Docosahexaenoic acid)作为大多数鱼饥饿后得以特别保留的高不饱和脂肪酸, 它对饥饿鱼体可能具有特殊的能量调控作用。为进一步探讨这一问题, 研究设计了以下饲养试验: 先在6%与12%两个油脂水平下分别添加3%DHA制品, 形成基础组、基础-DHA组、高脂组和高脂-DHA组共4组试验饲料。将尾均重为(14.81±0.13) g的鲤360尾随机分为4组, 每组3个重复, 每个重复30尾鱼, 分别用以上4组饲料对进行饲喂, 饲养74d后, 每个养殖缸随机余留6尾鲤(Cyprinus carpio L.)进行饥饿, 36d后检测饥饿鲤体重、生物学性状、体成分、血清生化指标等。结果显示: ①在同一脂肪水平下, DHA添加组饥饿鲤体重减重率均分别显著高于无DHA组(P<0.05); ②在2个油脂水平下DHA添加组饥饿鲤肝细胞直径均分别显著低于无DHA组(P<0.05); 鱼体肥满度、空壳比率等生物学性状在各组饥饿鲤间均无显著差异(P>0.05); ③在2个油脂水平下, DHA添加组饥饿鲤肌肉及肠脂肪含量均分别显著低于无DHA组(P<0.05), 而饥饿鲤肝胰脏脂肪含量在各组间均无显著差异(P>0.05); ④饥饿鲤血清生化指标在各组间均无显著差异(P>0.05)。结果表明, DHA添加组饥饿鲤体重、肝细胞直径以及肌肉及肠脂肪含量均呈显著下降趋势, 显示出DHA的添加未能协助鲤有效抵御饥饿等不良环境的胁迫。

THE EFFECT OF DHA FORTIFICATION ON BODY WEIGHT LOSS AND LIPID METABOLISM OF STARVED COMMON CARP (CYPRINUS CARPIOL.) IN TWO DIETARY LIPID LEVELS

Starvation is a special period when fish cannot effectively obtain food, resulting to some problems (i.e., lack of energy required). DHA (Docosahexaenoic acid), being highly unsaturated fatty acids retained in body during starvation, is postulated to contain special energy regulation effect on the starving fish body. To explore the effect of DHA fortification on body weight loss and lipid metabolism of starved common carp (Cyprinus carpio L.) in two dietary lipid levels, a feeding trail, which followed with starvation, was conducted. Firstly, 3% DHA product was added to 6% and 12% lipid levels diets to formulate four different kinds of diet respectively, (i.e., basic diet, basic-DHA diet, high lipid diet, and high lipid-DHA diet). A total of 360 common carp (14.81±0.13) g/tail were randomly divided into four groups (triplicate per each group), fed with four diets and reared in a recycling water rearing tanks, respectively. After 74 days of feeding, some fish per each tank were sampled and eventually 6 fish per each tank were left to endure 36 days of starvation. Then, all staved fish were sampled and weight of fish and the relative indexes were determined. Result showed that the body weight loss ratio of fish in DHA groups was significantly higher than that of the non-DHA groups in the same lipid level. Besides, the hepatocyte diameter and lipid content in muscle and intestine of starved fish in DHA groups were remarkably lower than that of the non-DHA groups (P<0.05). The lipid content in hepatosomatic and serum biochemical index of fish showed that there is no significant difference. The achieved result demonstrated that DHA fortification dietary groups had significantly lower body weight, hepatocyte diameter, as well as lipid content of muscle and intestine in starved common carp, which may reflect that DHA fortification had no great advantages in fostering common carp endure starvation.