DEVELOPMENT OF GASTRIC GLANDS IN PIARACTUS MESOPOTAMICUS LARVAE ADMINISTERED WITH A BACTERIAL MIXTURE CONTAINING THREE STRAINS OF BACILLUS SUBTILIS

GUIDOLI, MARCOS G.; HERNÁNDEZ, DAVID R.; BOEHRINGER, SILVIA I.; SÁNCHEZ, SEBASTIÁN; NADER MACÍAS, MARÍA E.

Botucatu

Simposio; SIMPÓSIO INTERNACIONAL DE NUTRIÇÃO E SAÚDE DE PEIXES AQUANUTRI; 2015

The use of native species to fish-farming in the Northeast of Argentina allowed an increase in the production, being Piaractus mesopotamicus the species of highest production. The characteristics of the intensive breeding system and the lack of knowledge of these newly used species led to the increase in stress levels and the incidence of diseases. Although antibiotics, used as growing factors, had solved the inconvenience, there is a worldwide tendency on the prohibition of the use of these substances in animals intended for human consumption. The use of probiotics in aquaculture emerged as a novel, safe and successful alternative to the use of chemotherapeutic drugs. There is a general consent over the fact that autochthonous microorganisms have higher probability of colonize, reside and become prevalent in the host, inducing a physiological beneficial effect. The objective of this work was to evaluate the effect of the administration of three autochthonous Bacillus subtilis on biological and histological parameters of P. mesopotamicus larvae in intensive breeding. Thus, the microbial mixture composed by the three autochthonous B. subtilis (Strains A252, A253 and A254) was administered to P. mesopotamicus larvae in three different stages (E: since eggs fertilization until the beginning of exogenous feeding, L: since the beginning of the exogenous feeding until the end of the assay at day 15 and E&L: since eggs fertilization until the end of the experiment) and three doses (6x104, 6x107 and 6x1010 UFC L-1 of each strain). Although statistical analysis did not show significant differences between treatments and the control group, average values showed that the dose 6x107 UFC L-1 strain-1 is the most adequate to be included in a bacterial mixture containing other beneficial microorganisms previously obtained by our group. The histological samples of the animals submitted to this dose in stageL showed the appearance of gastric glands, vestiges of what would be the pylorus and a higher development of liver, characteristics belonging to fishes in a more advanced stage of their biological cycle. These results showed, for the first time, the ability of a probiotic mixture to stimulate a faster development of the digestive system of fishes in intensive larviculture systems.