Evaluation of Black Soldier Fly Larvae Meal on Growth, Body Composition, Immune Responses, and Antioxidant Capacity of Redclaw Crayfish (Cherax quadricarinatus) Juveniles.

This study investigated the effects of substituting fish meal (FM) with black soldier fly (Hermetia illucens) meal (BSM) on the growth performance, body composition, immune response, and antioxidant enzyme activity of juvenile redclaw crayfish (Cherax quadricarinatus). Four isonitrogenous (41%) and isolipidic (11%) diets (i.e., FM substitutes) were formulated from BSM prepared using larvae that were fed soybean meal (BSM-S), fishery byproducts (BSM-F), or pitaya (BSM-P). The experimental diets were fed twice daily to triplicate groups of juvenile redclaw crayfish (0.56 ± 0.04 g). After the feed trial, the FM and BSM-F groups exhibited significantly lower feed conversion ratios and significantly higher weight gain; specific growth rates; and concentrations of saturated fatty acids, highly unsaturated fatty acids, eicosapentaenoic acid, and docosahexaenoic acid in the muscle. Among the tested groups, the BSM-F group exhibited significantly enhanced immune responses and increased antioxidant enzyme activity (i.e., superoxide dismutase, phenoloxidase, and glutathione peroxidase); the BSM-P group exhibited a significantly higher feed intake and hepatopancreatic index; and the FM group exhibited a significantly higher muscle body index and apparent digestibility for the dry matter of crude protein. The findings indicate that the juvenile redclaw crayfish fed BSM-F achieved the highest weight gain among the groups.

Dietary lipid level influences fatty acid profiles, tissue composition, and lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis.

Dietary lipids containing equal portions of soybean oil and fish oil were fed to juvenile Chinese soft-shelled turtle, Pelodiscus sinensis, at supplementation level of 0 to 15% for 8 weeks. Tissue fat contents of turtles increased when dietary lipid concentration increased. Fatty acid profiles for turtles fed diets supplemented with 6% or higher levels of lipids were similar to those in dietary lipids. On absolute value basis, fatty acids of 14-, 16-, and 18-carbons in muscle of turtles fed diet without lipid supplementation were higher than those in the initial turtle muscle. Among them, C16:1 and C18:1 was approximately 4 and 2 fold higher, respectively, than that of the initial turtles. By contrast, absolute amounts of C20:5 and C22:6 in muscle of turtles fed diet without lipid supplementation were slightly less than those in the initial turtles. For turtles fed lipid supplemented diets, tissue C20:5 and C22:6, however, increased when dietary lipid level increased. These results suggest that soft-shelled turtles are capable of synthesizing fatty acids up to 18 carbons from other nutrients and that they may have limited or no ability to synthesize highly unsaturated fatty acids. Lipid peroxidation measured by thiobarbituric acid-reactive substances in tissues of turtles fed 12% and 15% lipids was greater (p<0.05) than that in turtles fed 3% to 9% lipids. This could be due to high lipid and unsaturated fatty acid content in these tissues. On lipid basis, lipid peroxidation in turtles fed diet without lipid supplementation was the highest among all groups suggesting the existence of antioxidant factors in the dietary lipids.