Effects of dietary protein levels on the growth, digestive enzyme activity and fecundity in the oriental river prawn, Macrobrachium nipponense

Abstract

The effects of dietary different protein levels on growth performance, body composition, digestive enzyme activity and fecundity were tested in the oriental river prawn Macrobrachium nipponense. Five iso-energetic and iso-lipidic experimental diets were formulated with graded levels of protein [31.34% (A), 33.87% (B), 36.95% (C), 39.56% (D) and 42.58% (E)]. The results showed that M. nipponense fed diets with 39.56% protein level exhibited the best growth performance, survival, feed conversion rate and protein retention. Following the measurement of digestive enzyme activity in treatment D showed significantly improved (p < 0.05) hepatopancreatic amylase and protease activities compared with treatments A and B. Interestingly, dietary protein levels significantly affected the basal composition of eggs. Furthermore, the dietary protein levels of 36.95% and 39.56% showed significantly higher total protein and lipid content in eggs than the control (31.34%). According to the results of berried females, reduced spawning frequency towards the end of the feeding trial period was observed. Broken-line regression analysis indicated that the optimal dietary protein levels for egg quality are 37% (% dry matter) for juvenile Macrobrachium nipponense.