Potential of cowpea (Vigna unguiculata L.) meal as an alternative protein source in diets for giant freshwater prawn (Macrobrachium rosenbergii, de Man 1879)

Abstract

Growth trials were conducted to evaluate cowpea Vigna unguiculata (L.) meal as a potential protein source in diets for giant freshwater prawn, Macrobrachium rosenbergii (de Man 1879), reared in tank and lake-based cages. Five isonitrogenous (approximately 37% crude protein) and isocaloric diets were formulated where fish meal (FM) protein was replaced with 0%, 15%, 30%, 45% and 60% cowpea meal protein (or CP0, CP15, CP30, CP45, and CP60, respectively). Results of an 8-week tank trial showed that the final body weight (FBW), percent weight gain, specific growth rate (SGR) and survival of prawns were not significantly influenced by dietary treatments (P > 0.05), although the highest values, except for survival, were observed with CP45. In a lakebased cage trial that lasted for 16 weeks, prawns fed CP30 and CP45 had significantly higher FBW (13.1 and 14.4 g, respectively) compared to other treatment groups (P < 0.05). SGR (4.52 5.00%/ day), survival rates (53-77%), yield (98.5-116.5 g m-2) and feed conversion ratio (FCR; 2.0-2.7) were not affected by increasing levels of cowpea meal in the diets. Based on these results, cowpea meal can be considered as an alternative protein source in diets for M. rosenbergii.