Replacement of living microalgae with a dried alfalfa chloroplast product in diets for the Brown mussel (Perna perna), Yellow clam (Mesodesma mactroides) and Manila clam (Venerupis philippinarum)

Abstract

Owing to its high nutritional value and widespread availability, the legume alfalfa Medicago sativa (Linnaeus, 1753) is a possible feed for aquatic animals. In this study, a dried alfalfa chloroplast (DAC) product supplied by Virentia Inc., Quebec, Canada, was evaluated as a partial or total replacement for live microalgae (LM) in diets for juveniles of Perna perna and the Mesodesma mactroides—two species with high aquaculture potential in Brazil. In addition, trials were conducted with Venerupis philippinarum, a species commonly used in global aquaculture. Nine diets containing different ratios (based on dry weight) of live microalgae (Chaetoceros neogracile and/or Isochrysis galbana) and DAC were evaluated. With all three bivalve species, additions of DAC to partial microalgal rations increased final dry and organic weights, compared with those provided with partial algal rations alone. M. macrooides and P. perna appeared to utilize DAC to a greater extent than V. philippinarum as indicated by the higher final organic weights obtained by these two species when larger fractions of LM were substituted with DAC. Overall, the results of this study indicate that DAC supplements can be useful in supporting mussel and clam tissue growth when algal feeds are limited or unavailable.