Study of non-specific immune responses and enzymatic hemolymph parameters of the oriental river prawn, Macrobrachium nipponense fed different dietary astaxanthin levels

The present study was aimed to evaluate the effects of astaxanthin on immunological and enzymatic hemolymph parameters of the oriental river prawn (Macrobrachium nipponense). In this research, two hundred and twenty-five prawns with mean weight of 1.40±0.05 gram were fed by five dietary treatments and three replications including different levels of astaxanthin containing zero (control), 50, 100, 150 and 200 milligrams astaxanthin per kilogram diet for eight weeks. At the end of the culture period, after collecting the hemolymph of prawns, immunological parameters and hemolymph enzymes of the samples were evaluated by experimental kits, ELISA reader instrument and optical microscope. The results of the study showed that the innate immune and enzymatic hemolymph parameters of prawn hemolymph were affected by different levels of astaxanthin (P<0.05). With increasing dietary astaxanthin levels, the immunochemical parameters such as albumin and total protein of prawn hemolymph increased significantly while cortisol levels decreased (P<0.05). Cellular immunity parameters such as total hemocyte count, granular cells, semi-granular cells and hyaline cells, also increased significantly with increasing dietary astaxanthin (P<0.05). Hemolymph enzymes such as lysozyme and phenol oxidase were higher in treatments containing astaxanthin than control treatment, while alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and lactate dehydrogenase were significantly reduced (P<0.05). Finally, the findings of this study showed that increasing dietary astaxanthin levels improves the non-specific immune response and enzymatic hemolymph parameters of the oriental river prawn and adding 150 milligrams per kilogram of this pigment to the diet was suggested to improve the parameters that mentioned of this prawn.