Dietary Ocimum gratissimum essential oil improves intestinal microbiota and morphology of Piaractus mesopotamicus
Plant essential oils have been reported to present several beneficial effects for fish such as increased intestinal microflora modulation, improved nutrient absorption through beneficial effects in intestinal morphometry and improvements in productive parameters. In this study, juveniles of pacu (Piaractus mesopotamicus), an important fish species for neotropical aquaculture, were fed with 0.5 and 1% of Ocimum gratissimum essential oil (EO) for 30 days. At the end of this period, the intestinal microbiota of the pacus was relatively quantified through qPCR, and the intestinal morphometry was evaluated using histometric methods. Fish were also measured and weighed, and the productive parameters were calculated. O. gratissimum EO feeding at 1% significantly altered the intestinal microflora of juvenile pacus, resulting in higher relative quantification in bacteria from the genera Enterococcus, Bacillus and Lactobacillus when compared to 0.5% and control groups. O. gratissimum EO feeding also significantly affected their intestinal morphometry, increasing the villi thickness and area at 1% of EO and decreasing the same parameters at 0.5% of EO when compared to the control. No significant effects were observed in productive parameters. Our results suggest that the exposure of P. mesopotamicus to O. gratissimum at 1% concentration for 30 days modulates the intestinal microbiota and increases the intestinal nutrient absorption area.