Effect of diets with molasse yeast in the glicemia and in the levels of liver glicogen and total liver lipid of Nile tilapia (Oreochromis niloticus)

Abstract

In order to evaluate the effect of molasse yeast (Saccharomyces cerevisiae) as replacement for vitamin premix in diets for Nile tilapia (Oreochromis niloticus), in the glycemia and in the levels of liver glycogen and total liver lipid, 300 male fingerlings sex-reversed, averaging 1.5 g Iive weight, were stocked in circular 270-L biofilter equipped fiberglass tanks (15 fish/tank), and fed to satiety twice a day a 32% crude protein (CP) diet for 40 days, followed by a 28% CP diet for 74 days. Test diets were prepared to contain at least 10% yeast as replacement for the vitamin premix, and a diet without yeast was used as control. Water temperature was monitored daily and water pH and dissolved oxygen were measured weekly. Blood glycemia and total lipid and glycogen contents of the Iiver were evaluated. Fish fed yeast-containing diets presented reduced Iiver glycogen, and increased total liver lipids, as compared to fish fed the control diet. No pathological effect could be attributed to the molasse yeast used in the diets of Nile tilapia.