Protein requirement for maintenance and maximum weight gain for the Pacific white shrimp, Litopenaeus vannamei

The dietary crude protein requirement of penaeid shrimp is an important nutritional consideration because protein is often the major limiting nutrient for growth. In most cases, research has focused on total dietary protein levels rather than a daily requirement for protein. This research utilized three practical diets containing 16%, 32%, and 48% protein and various daily rations to estimate daily requirements for protein. In the first series of studies, four 28-day feeding trials were conducted to determine the maintenance requirement for protein (protein required to maintain body functions with all other nutrients provided in adequate amounts) by juvenile and subadult shrimp. Shrimp were offered practical diets containing 16% or 32% crude protein. In order to estimate the maintenance requirement, weight gain was regressed against daily protein ration. Juvenile shrimp were found to have maintenance protein requirements in the range of 1.8-3.8 g dietary protein/kg body weight per day (g DP/(kg BWd)), and subadult shrimp were found to have maintenance protein requirements in the range of 1.5-2.1 g DP/(kg BWd). Four additional 28-day feeding trials were conducted to determine the protein requirement for maximum growth by juvenile and subadult shrimp. These studies, utilized three practical diets containing 16%, 32%, and 48% dietary protein. On an isonitrogenous basis, the 16% protein diet produced significantly lower weight gain, feed efficiency (FE), and protein conversion efficiency values, than the 32% protein diet for both the juvenile and subadult shrimp. The 48% protein diet produced significantly lower weight gain in the juvenile shrimp, but there was no significant effect in the subadult shrimp. Feed efficiency values were higher for shrimp fed the 48% protein diet as compared to those offered the 32% protein diet. Broken line analysis was conducted on the growth responses for each diet and each size of shrimp, in order to determine the protein requirement for maximum growth. Protein requirement for maximum growth of juvenile shrimp was found to be 46.4 g DP/(kg BWd) when fed the 32% protein diet and 43.4 g DP/(kg BWd) when fed the 48% protein diet. Subadult shrimp exhibited a maximum protein requirement of 23.5 g DP/(kg BWd) when fed a 32% protein diet and 20.5 g DP/(kg BWd) when fed a 48% protein diet. In summary, FE increased as the protein concentration of the diet increased, and decreased as feeding rates (offered feed/day) increased, Weight gain reflected daily protein intake. Based on these results, a wide range of dietary protein levels could be used to produce maximum weight gain of juvenile and subadult shrimp. Due to a restriction of feed intake and consequently protein intake, low protein diets did not support maximum weight gain. (C) 2002 Elsevier Science B.V. All rights reserved.