EFFECT OF DIET AND FEEDING REGIME ON NITROGENOUS WASTE PRODUCTION OF BARRAMUNDI, LATES CALCARIFER

Abstract

In the present study, juvenile barramundi (34.45 g ± 1.17 to 214 g ± 4.5) were used and experiments reared individually in 70 L aquaria in a recirculating seawater system for 56 days were conducted in the Aquaculture Research Aquarium at Townsville, Queensland Australia. Restricted feeding regimes, isoenenergetic and isonitrogenous feeding, in combination with diets varying in protein and energy content were used to examine the potential of non-protein energy to spare dietary protein for barramundi. Diets containing two protein levels (40 and 50 %), and three energy levels (16, 20 and 24 MJ kg^-1), were formulated. Diets were fed isoenergetically at 0.64 MJ kg^-1 day^-1 and isonitrogenously at 16 g protein kg^-1 day^-1. Determination of ammonia production in response to diet and feeding regime indicated that ammonia production was governed by protein intake, or dietary protein level, with some effect of dietary non-protein energy. Suggesting that reducing the dietary protein level is fundamental to reducing ammonia excretion and water eutrophication.