科研之友
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摘要
l-ascorbyl-2-polyphosphate (ApP) was used as a vitamin C source to investigate the ascorbic acid (AsA) requirements on growth performance and stress resistance of the larval white shrimp, Litopenaeus vannamei. Five isoenergetic and isonitrogenous fish meal-fish protein hydrolysate-based diets with five levels of ApP, AsA equivalent to 91.8, 188, 271, 360 and 436 mg kg(-1) diet were fed to triplicate groups of L. vannamei (mean initial wet weight 1 mg) for 32 days. The diet with AsA 91.8 mg kg(-1) showed high cumulative mortality after 10 days of feeding. After the 32-day trial, the shrimp that fed the diet had significantly lower survival and weight gain (WG, %) than those that fed 188, 271, 360 and 436 mg AsA kg(-1) diets. Specific growth rate (SGR, % day(-1)) and final body wet weight (FBW, mg) showed the same pattern as WG (%). There were no significant differences in growth performance (FBW, WG and SGR) among the groups that fed 188, 271, 360 and 436 mg kg(-1) of AsA at the termination of feeding trial. Broken-line regression analysis on WG indicated that 191 mg AsA kg(-1) in the diet was the optimum for larval L. vannamei. On the contrary, dietary level of more than 360 mg AsA kg(-1) was needed to ensure high resistance to stressful conditions such as low dissolved oxygen stressors.
