Metabolic requirement for protein by pacific white shrimp, Metabolic requirement for protein by pacific white shrimp, Litopenaeus vannamei. Litopenaeus vannamei. 1

The dietary protein requirement of penaeid shrimp is an important nutritional consideration because it is a major limiting nutrient for growth. In most cases, research has focused on dietary protein levels rather than on the actual requirements for protein. In this study, four 28 da y 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 sub -adult 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/day (g DP/ (kg BW * d)), and sub-adult shrimp were found to have maintenance protein requirements in the range of 1.5 -2.1 g DP/ (kg BW * d). Four additional 28-day trials were conducted to determine the protein requirement for maximum growth b y juvenile and sub- adult shrimp. On an isoproteic basis, the 16% protein diet produced significantly lower weight gain, feed efficiency, and protein conversion efficiency values than the 32% protein diet for both the juvenile and sub - adult shrimp. The 48% protein diet produced significantly lower weight gain in the juvenile shrimp, but there was no significant effect in the sub -adult shrimp. Feed efficiency values were higher for shrimp fed the 48% protein diet as compared to those offered the 32% protein d iet. 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 BW * d) when fed a 32% protein diet and 43.4 g DP/ (kg BW * d) when fed a 48% protein diet. Sub - adult shrimp exhibited a maximum protein requirement of 23.5 g DP/ (kg BW * d) when fed a 32% protein diet and 20.5 g DP/ (kg BW * d) when fed a 48% protein diet. In summary, FE increased with the protein content of the diet and decreased with increasing feeding rates. Weight gain corresponded to daily protein intake. Based on these results a wide range of dietary protein levels could be used to produce maxim um weight gain. However, due to restriction on feed intake and consequently protein intake, low protein diets may not support maximum growth.