Effect of Optimum and Suboptimum Dietary Protein on Hemolymph Physiology, Oxidative Physiology, Plasma Fatty Acids, and Histoarchitectural Modulations in Farmed Giant Freshwater Prawns Macrobrachium rosenbergii

Abstract

AbstractWe examined the effect of optimum (32%) and suboptimum (27%) levels of dietary protein on the hemolymph and oxidative physiology of giant freshwater prawn Macrobrachium rosenbergii juveniles. Wild juveniles of different stocks were collected from the west coast (Gujarat [G‐stock] and Maharashtra [M‐stock]) and east coast (Andhra Pradesh [A‐stock]) of India. Prawns were raised in 200‐m2 culture ponds, with individual animals tracked by using stock‐specific, colored elastomer tags. Hemolymph glucose, plasma total protein, albumin‐to‐globulin (A:G) ratio, plasma calcium, and activity of five key metabolic enzymes in plasma (plasma cholinesterase, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, and amylase) were examined to compare the hemolymph physiology due to dietary protein variations fed to the different stocks. Plasma fatty acid profile was also monitored. Effect of feeding on oxidative physiology of prawns was analyzed by measuring the catalase and acetylcholinesterase activity in peripheral and brain tissues, respectively. Oxygen‐dependent intrinsic defense ability was also measured by nitro blue tetrazolium‐based respiratory burst activity. Physiology of prawns was correlated with the histological examinations of hepatopancreas and gills. Our results suggest that the hemolymph and oxidative physiology of giant freshwater prawns remained unaffected by the optimum and suboptimum dietary protein levels fed. Furthermore, stock‐based differences in the response were evident: the G‐stock and M‐stock prawns exhibited healthier plasma and oxidative physiology than A‐stock prawns. Our study provides a useful tool to select “good responder” stocks (genotypes) to obtain higher production levels in a given culture management scheme.