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% (T2) or phytase 500 FTU (T3) or both lysine 1% and phytase 500 FTU (T4), whereas no supplementation was taken as control (T1) 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−N, NO2−N 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.