Lysine and/or phytase supplementation in the diet of Penaeus monodon (Fabricius) juveniles:: Effect on growth, body composition and lipid profile

A 60 days experiment was undertaken to study the effect of dietary supplementation of lysine and/or phytase on growth, body composition and fatty acid profile of P. monodon juveniles. Two hundred tiger shrimp, Penaeus monodon (Fabricius) juveniles (initial body weight: 140+/-2.5 mg) were divided into four treatment groups with each of four replicates. Four isocaloric (457.56+/-0.83 kcal/100 g)and isonitrogenous (34.84% crude protein) soybean meal based diets were prepared by supplementing with lysine 1% (T-2) or phytase 500 FTU (T-3) or both lysine 1% and phytase 500 FTU (T-4), whereas no supplementation was taken as control (T-1) group. Dietary lysine supplementation had a significant effect (P < 0.05) on growth performance and feed conversion ratios, but dietary phytase supplementation had no effect (P > 0.05) on growth. Either extract content of the whole tissue reduced significantly (P < 0.05) with the phytase supplementation. Saturated and mono-unsaturated fatty acids content of whole tissue decreased significantly (P < 0.05) with the dietary lysine supplementation but had no effect (P > 0.05) on phytase supplementation. Total n-3 content was reduced and n-6 content increased significantly (P < 0.05) with the both lysine and phytase supplementation group compare to control. Only lysine supplementation in the diet reduced the nitrogen (NH4-, NO2-, and NO3-N) discharge significantly, whereas phosphorus excretion was reduced in the phytase supplemented group. This concludes that supplementation of both lysine and phytase in soybean-based diet not only reduces the nitrogen and phosphorus load of the culture system but also significantly changes the fatty acid profile of the tissue of the P. monodon. (c) 2006 Elsevier B.V All rights reserved.