In vivo evaluation of indigenous enterococci strains on biometrical parameters of Piaractus mesopotamicus embryos and larvae

Abstract

The use of autochthonous microorganisms as probiotics is a novel and promising alternative for the preventive application of antibiotics. Lactic acid bacteria (LAB) are one of the most successfully microorganisms used as probiotics and applied in different niches. The aquaculture of Piaractus mesopotamicus in Northern Argentina has increased exponentially, but the use of this native species in production systems led to a deficit in the availability of larvae for breeding and fattening. The objective of the present study was to evaluate the effect of the addition of two different formulae containing autochthonous beneficial LAB strains on the survival, mean weight and biomass of larvae under laboratory intensive breeding. Results indicate that the bacterial administration does not cause any significant effect on the variables evaluated. However, statistical analysis showed a tendency of the 6x107 CFUL-1 dose of one of the formula to stimulate an increase of mean weight and biomass. On the other hand, the average values of biometrical parameters obtained with the second formula, indicate that the optimum dose is 6x104 CFU L-1. These results and the histological confirmation of the harmfulness of the strains, allowed us to select these doses for their use in a combined probioticmixture to be tested in future assays.