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.