Effect of Different Dietary Protein Levels on Body Composition, Digestive Enzymes, Hemolymph Indexes and Water Quality in White Shrimp Larvae Litopenaeus vannamei Cultured in Tanks

The present experiment was conducted to investigate the effects of five different protein levels (25%, 30%, 35%, 40% and 45%) on white shrimp larvae Litopenaeus vannamei on body composition, digestive enzymes, haemolymph indexes and water quality cultured in tanks. The experiment was performed indoor at Invertebrate laboratory of National Institute Oceanography and Fisheries (NIOF), Suez governorate, Egypt for 90 days. The experiment was carried out in 15 rectangular tanks (66×47×44cm, 50 L) each of reinforced with water salinity 20 ppt. Triplicate groups of shrimp with an initial weight of ,(0.002g) were fed twice a day at a ratio of 14% from body weight  and re-adjusted gradually to 5% at the end of the experiment. The results observed that, by increasing dietary level of protein, the activity of trypsin increased up to 35% and then decreased. The highest activity values of trypsin were recorded for larvae fed 35% protein level compared to the other diets. No significant differences were recorded for lipase or amylase activity values among different experimental treatments. The percentages of total protein and cholesterol in plasma were increased in all treatments. The different protein levels also affected the production of nitrogenous compounds such as ammonia (TAN), nitrite (NO2) and nitrate (NO3). The obtain results indicate that 35% protein level may achieve the highest proximate body composition induces of white shrimp L. vannamei larvae cultured in tanks