Substituting fishmeal with mixtures of wheat, corn and soya bean meals in diets for the white leg shrimp, Litopenaeus vannamei (Boone): effect on production parameters and preliminary economic assessment

摘要

We analysed the effect on production and economic performance of juvenile Litopenaeus vannamei of isoproteic diets substituting fishmeal by 25%, 50%, 75% and 100% with mixtures of wheat, soya bean and cornmeals. In a laboratory trial, 10 juveniles m(-2) (1.1 +/- 0.1g) were reared in 60-L plastic containers using a recirculation system for 90days. Three replicates were used to test each diet. A commercial diet serving as a reference and the diet with the highest content of essential amino acids (50% substitution, 6.46 +/- 1.1g) produced significantly higher shrimp final weight (7.12 +/- 0.9g, P0.05). There were not significant differences in specific growth rate and mean survival (85.9 +/- 0.2%, P>0.05). In a pond trial, 10 shrimp m(-2) (1.08 +/- 0.3g) were cultivated in 1.5m(-3) cages for 35days, testing the diets in triplicate. Final weight was significantly higher (P0.05) when 100% substitution was used (10.89 +/- 0.24g), while survival did not differ significantly among diets (P>0.05). The optimal level of substitution was estimated at 86.0%. Apparently, nutrients contained in the diets combined well with natural feed available in the pond, up to a point where 7.3% of fishmeal inclusion is recommended. An economic analysis showed that 100% substitution produced the best results. We conclude that mixtures of wheat, corn and soya meals are potential alternatives to replace fishmeal effectively in diets for L.vannamei.