Crescimento e histopatologia hepática de tilápias do nilo alimentadas continuamente com Microcystis aeruginosa liofilizada e L-carnitina dietética em condições laboratoriais

Abstract

The aim of this study was to evaluate the effect of the addition of L-carnitine (LC) on the performance and histology of juvenile liver of Nile tilapia subjected to repeated doses of microcystins (MCs). To this end, lyophilized cells of cyanobacteria (CIAN) Microcystis aeruginosa strain NPJL-4 were included (3.3%) in diets without L-carnitine (CIAN), 1 g Lcarnitine kg-1 (CIAN+LC-1), 2 g of L-carnitine kg-1 (CIAN+LC-2) and without CIAN and LC (CONT). Juvenile Nile tilapia (± 4.8 g initial weight) were distributed in 60L tanks (20 fish / aquarium). The diets were fed for 28 days in three meals a rate of 5% of the biomass so as to provide 1.2 ug MC-LR, g-1/fish/day. On days 0, 3, 7, 14, 21 and 28 samples of liver were collected for histological analysis. The survival and growth performance were not affected (p>0.05) by treatments. The foremost liver injury induced by MC intake was disorganization and necrosis of hepatocytes and pancreatic megalocytosis clutter. We could not find any significant protective effect of L-carnitine in Nile tilapia eating MCs repeatedly. The species showed high resistance to continuous intake of microcystins for 28 days.