Probiotic addition effect assessment in the diet of fingerling and juvenile Nile tilapia (Oreochromis niloticus) created in treated sewage

ABSTRACT The research was conducted to evaluate the effect of using probiotic (Bacillus licheniformis, Bacillus cereus, Bacillus subitillis, yeasts and Saccharomyces cerevisiae and Saccharomyces boulardi) in diets for tilapia, during the fingerling and juvenile stages, that underwent sanitary challenge on performance, chemical composition of the carcasses and water quality. We used three hundred and sixty fingerlings with initial average weight of 2.91±0.37 g and initial average length of 3.30±0.27 cm. The treatments were: T1) farmed fish in clean water, fed with commercial food without the use of probiotics; T2) fish reared in treated sewage water and fed with commercial food without the use of probiotics; T3) farmed fish in a condition similar to T2, with food plus probiotic. In the evaluation of physicochemical parameters of the treated sewage, regardless of the presence or not of probiotic strains, it presents a high primary productivity. The use of probiotics (Bacillus licheniformis, Bacillus cereus and Bacillus subitillis and yeasts - Saccharomyces cerevisiae and Saccharomyces boulardi) promotes improvements in the parameters of feed intake and specific growth rate in the Nile tilapia grown in treated water from sewage, reduces the proportion of lipids in weight gain and increases the proportion of crude protein in weight gain. However, it does not influence weight gain, feed conversion and fish survival. Fish grown in treated sanitary sewage, regardless of the use or not of probiotic strains have a higher protein content and lower fat content.