Histologia intestinal de tilápia do Nilo Oreochromis niloticus submetidas a diferentes níveis de suplementação do extrato hidroalcoólico de Anacaridium occidentale na dieta

Abstract

This study evaluated the effect of supplementation with the hydroalcoholic extract of Anacardium occidentale bark on the intestinal morphology of Nile tilapia (Oreochromis niloticus) fingerlings. After a 15-day acclimation period, during which the fish were maintained in 250-liter tanks, they were transferred to 40-liter experimental units at a density of 250 fish/m³ each. The hydroalcoholic extract of Anacardium occidentale bark was added to the diets administered to the animals at concentrations determined in the minimum inhibitory concentration (MIC) assays. Four treatments were evaluated: (i) commercial feed with 3% A. occidentale extract, (ii) commercial feed with 4% A. occidentale extract, (iii) commercial feed with 5% A. occidentale extract, and (iv) control group (commercial feed without extract addition), all with four replicates each. The experiment lasted 30 days, and the diets were offered three times a day (08:00, 12:00, and 16:00 hours) to apparent satiety. For histological analysis, five fish were collected at the beginning and one fish at the end of the experimental period (one per replicate for each treatment). The intestines were exposed in Petri dishes and divided into three segments: anterior, middle, and posterior. A 3 cm portion of the middle intestine was used, which was longitudinally cut to expose the villi. The total height, height, width, and thickness of the villi were measured. As a result, higher mean values for all intestinal morphology variables evaluated (height, total height, thickness, and width of the villi) were observed in the groups supplemented with 3%, 4%, and 5% of the hydroalcoholic extract of A. occidentale bark compared to the control group, with no differences among the treatments that received the extract. In conclusion, the supplemental use of the hydroalcoholic extract of Anacardium occidentale bark in the diet of Nile tilapia fingerlings resulted in a beneficial effect on the intestinal morphology of the supplemented animals, indicating improved development regarding intestinal health.