Prebióticos, probióticos e simbióticos em dietas de juvenis de tilápias-do-Nilo

Abstract

The aim of this study was to evaluate the effect of prebiotic, probiotic and symbiotic inclusion on productivity and physiological parameters of Nile tilapia juveniles. A total of 300 animals with an initial average weight of 11.3±0.32 g and an initial average length of 8.5±0.57 cm were used, distributed in a completely randomized design in 15 water tanks (2000 L), with three replications. in each treatment, during a period of 60 days. The fish were fed a commercial diet of 32% crude protein and additives were added through an oil bath (2%), in addition to a diet free of the additive. The treatments were named Control (additive free), PROB (4g.kg-1) composed of a mix of probiotics such as Bacillus subtilis, PREB MOS (4g.kg-1), SIMB I (2g.kg-1 probiotic + 2g.kg-1 prebiotic) and SIMB II (4g.kg-1 probiotic + 4g.kg-1 prebiotic). The addition of the additives effected the treatment, and improved the performance in the following efficiency rates: feed conversion dicient of the additives only of the intestinal treatment, and for which the SIMB II obtained the highest value of this parameter. The proximate composition was not altered by the addition of additives in the diets, but the additives improved protein retention, while the SIMB II treatment showed a higher plasma glucose index. The development of liver cells was influenced by the inclusion of additives, with reduced height and width of hepatocytes, but organ integrity did not differ significantly between treatments. There were no differences between treatments in midgut histology, as well as in liver and intestine enzymatic analysis, only plasma glucose showed significant differences among treatments in which SIMB II showed higher glucose levels. The multivariate analysis showed that the control group was completely different from the others. The use of MOS additives and probiotic mix composed with Bacillus subtilis (in concentrations of 5 x 109 CFU) improved both the development and the health status of juvenile tilapia (Oreochromis niloticus) throughout the growth period and the use is recommended of the SIMB I dose (2g.kg-1 of probiotic + 2g.kg-1 MOS).