Essential oil of Aloysia triphylla as feed additive promotes growth of silver catfish (Rhamdia quelen)

This study examined the growth, gut morphology and occurrence of endocrine cells in the gastrointestinal tract of silver catfish (Rhamdia quelen) fed diets supplemented with essential oil (EO) extracted from Aloysia triphylla (0 – control, 0.25, 0.5, 1.0 and 2.0 mL EO per kg of diet) for 60 days. The group fed 2.0 mL EO per kg of diet showed better results after 60 days in growth, body weight, weight gain and specific growth rate. Histological and immunohistochemical analyses in the intestine demonstrated that height of folds was significantly higher in the control group and 0.25 mL EO compared to those fed 0.5 mL EO per kg of diet. There was a significant increase in the number of folds in fish fed 1.0 and 2.0 mL EO per kg of diet compared to control group. The enterocyte height was significantly lower in those fed 1.0 mL of EO group compared with 0.25 mL of EO per kg of diet. The number of cells that reacted to cholecystokinin and neuropeptide Y did not differ between groups. The addition of 2.0 mL EO per kg of diet increases silver catfish growth, and consequently, its use is recommended as a feed additive.