Influência de probióticos na prevalência parasitária e níveis de glicose e cortisol em tilápia do Nilo.

The addition of probiotics in diets aims to act as a growth promoter of intestinal flora species that make use of it. The nursery phase in cages uses high density of fish that can lead to more frequent instances of stress that can leverage the most serious problems in production. The probiotics appears as an alternative to minimize or prevent damage. The objective of this study was to evaluate the influence of probiotic Bacillus cereus var. Toyoi and Bacillus subtilis C-3201 in the parasitic prevalence and verify the health status through the biochemical profile of glucose and cortisol and Fulton condition factor (Kf) to act as a quantitative indicator of welfare of Nile tilapia GIFT strains created in cages system profile. A total of 1800 juveniles of Nile tilapia were distributed in 20 cages of 4.0 mm and 0.5 m x 0,5 m x 0,7 m individually installed in tanks with low water renewal. The fish without the addition of probiotics (T1) received just the basal diet feed with vegetable oil added in the same proportions used in all experimental groups. The basal feed was added at levels of 0.5 % of B. cereus var. (T2), 0.5 % of B. subtilis (T3), 0.25 % of B. cereus + 0.25 % of B. subtilis (T4). The diets with addition of B. cereus and/or B. subtilis were not effective in controlling the parasitic infestation by monogenean and tricodinids. There was a greater (p<0.001) incidence of Gyrodactylus spp. (71 %) in the gills compared to prevalence of parasites on the skin or fins, while Apiosoma sp. infestation was greater (p<0.001) in the skin of juveniles. The prevalence of Epistylis sp., Ichthyophthirius multifiliis and Ambiphrya spp. did not present significant difference between the assessed organs. The level of blood glucose was higher (p<0.05) in tilapias fed a diet free of additives. The dietary probiotic B. cereus and/or B. subtilis not positively contribute to the reduction the prevalence of ectoparasites on fish mucus. Regardless of the diet, the Nile tilapia skin is the most affected organ by parasitic infestation by Trichodina sp., while the gills have a higher prevalence of Monogenea. The health status of juvenile Nile tilapia monitored through biochemical profile of glucose and cortisol, and Fulton condition factor (Kf) is not influenced by the dietary addition of probiotic Bacillus spp. [ABSTRACT FROM AUTHOR]