Abstract:
An experiment was conducted to study the effect of protein level on the growth rate, survival, pre- and postprandial oxygen consumption, and ammonia (N-NH3) excretion in white shrimp, Penaeus setiferus (L.), juveniles. Diets containing 10%, 20%, 30%, 40% and 50% protein were provided at a proportion of 15% of the dry weight of shrimp weighing 0.19 +/- 0.01 g. The instantaneous growth rate was recorded for 45 days. The optimum protein level, in terms of the best growth rate, was that of the 30% protein diet (1.15 g 45 days(-1)). All shrimp fed with the diets had significantly higher respiration rates after feeding because of the apparent heat increment (AHI), A greater postprandial nitrogen excretion (PPNE) excretion was also observed after feeding, Shrimp maintained on the 30% protein diet had the lowest AHI and PPNE coefficients (percentage of ingested energy), and took the least time to reach the oxygen consumption and nitrogen excretion peak. The O:N ratios varied according to protein level, with higher values (32 and 44, fasting and feeding, respectively) with a 30% protein diet, and lower values (10 and 13, fasting and feeding, respectively) with 10% and 50% protein diets. These results indicate that P. setiferus juveniles use protein when fed with high (50%) and low (10%) protein diets, and lipid-protein substrates with a 30% protein diet, Under these conditions, P. setiferus grow better with a 30% protein diet where shrimp use food more efficiently.