Effects of supplementary astaxanthin in egg custard on antioxidant capacity and non-specific immunity during larvae metamorphosis of giant freshwater prawn (Macrobrachium rosenbergii)

The effects of different astaxanthin levels on antioxidant capacity and non-specific immunity in phase V similar to X larvae of giant freshwater prawn, Macrobrachium rosenbergii, were investigated; furthermore, the differential gene expression was compared. For this experiment, 60,000 larvae were allocated into five treatments with six replicates. Astaxanthin supplementing in steamed eggs with graded effective content as 0 (control group, A(0)), 50 (A(50)), 100 (A(100)), 200 (A(200)), 400 (A(400)) mg kg(-1) were fed from phase V to X larvae respectively. Feeding trials lasted for 18 days. The results showed that acid phosphatase (ACP), alkaline phosphatase (AKP), total antioxidant capacity (T-AOC), glutathione reductase (GR), total superoxide dismutase (T-SOD) activities were declined significantly compared with the control (P < 0.05); catalase (CAT) activities decreased among treatments; lysozyme (LZM) activities both in treatments A(50) and A(400) was lower than the control significantly (P < 0.05), while the opposite phenomena were observed among other treatments; glutathione peroxidase (GSH-Px) activities both in treatments A(200) and A(400) significantly elevated than that among A(0), A(50), and A(100) (P < 0.05). There was no significant difference in cytochrome oxidase activity (CCO) among treatments except that in A(100) (P > 0.05). Nineteen common differential genes were screened out by means of transcriptome analysis. This study implies that excessive addition of astaxanthin may take a negative effect on larvae development of M. rosenbergii by way of suppressing the antioxidant system and non-specific immunity function, and its possible mechanisms need to be investigated furthermore.