Effect of an herbivorous diet on energy balance of Litopenaeus vannamei at selected ontogenetic stages

Abstract

Herbivorous (20% vegetable protein, 40% carbohydrate) and carnivorous diets (40% marine animal protein, 20% carbohydrate) were experimentally tested to assess their effect on the energy balance and energetic substrates utilized by postlarvae (PL's /15 days) and juvenile shrimp (3–6 g) of Litopenaeus vannamei. Postlarval stage 60 (PL 60, early juveniles) shrimps fed HeD and CaD diets, then late juveniles (3–6 g) acclimated to the same diets were tested for their respective energy partitioning potential. No significant differences ( p > 0.05) on growth were obtained in early juveniles (mean final wet weight of 0.19 g). However in late juvenile stages a significant difference ( p < 0.05) in growth rate was observed. In terms of energy partitioning, both early and late juveniles seem to spend more energy in respiratory metabolism than in the elimination of excretion products. A change in feed composition based on quality protein sources induced some modifications on shrimp's activity measured by heat increment. Shrimps fed with an herbivorous diet showed a higher heat increment. Interestingly, the early stages of L. vannamei display a remarkable capacity to assimilate a plant protein-based and a high carbohydrate level diet. Such capacity with a stimulation of genes would lead to a good adaptation of juveniles receiving all-plant diets to sustain growth performances up to a marketable size. The implications of these findings for the shrimp farming feeding costs are briefly discussed.