Substitution of fishmeal with soybean meal in practicaldiets for juvenile white shrimp Litopenaeus schmitti (Pérez-Farfante & Kensley 1997)

Abstract

The feasibility of substituting soybean meal for ¢shmeal diets for juvenile white shrimp Litopenaeus schmitti (0.35 0.01g) was evaluated, and an adequate substitution level was determined. Five diets were evaluated using 46%, 59%, 75%, 88% and 100% substitution levels. Pellet water stability was signi¢cantly a¡ected by dietary soybean content (Po0.05). Increased soybean content produced lower pellet stability, ranging from a dry matter loss of 14^ 22% after a 2-h immersion, and 20^33% after an 8-h immersion. After 52 days, signi¢cant di¡erences (Po0.05) were found in shrimp weight, feed conversion ratio and protein e⁄ciency ratio. The values were 0.64^1.06 g, 2.8^7.9 and 0.45^1.21, respectively, for the three measurements. Overall, better results were obtained with diets where soybean meal was substituted for ¢shmeal up to 75%. The 100% soybean meal diet resulted in poor growth performance of shrimp. Survival rates were acceptable for all treatments (90% or higher) and no signi¢cant di¡erences were found in survival between treatments. Regression analysis using the broken-line methodology indicated that 76.5 2% is an optimum soybean substitution level in diets that contained ¢shmeal and soybean as the major protein sources for growout of juvenile white shrimp.