Protective effect of nutraceutical food on the intestinal mucosa of juvenile pacu Piaractus mesopotamicus under high stocking density

Nutraceuticals have been evaluated for their ability to protect and heal the gastrointestinal mucosa, especially in adverse conditions. Thus, the present study evaluated the effect of a nutraceutical diet composed of bovine first milk secretion in the intestinal health of juvenile Piaractus mesopotamicus subjected to high stocking density. Juveniles (140 ± 10 g) distributed into 16 cages and stocked at 50 kg m −3 were fed twice daily with a pelleted and semi-purified diet containing nutraceutical food (NF) in increasing levels, being 0, 10, 20, and 30% of inclusion ( n = 4). Quantification of goblet cells containing neutral, acidic (including sialo and sulfomucins) and acidic-neutral mucins, volume ( Vv ), and surface density ( Sv ) of the mucosa and thickness of the internal circular muscle layer was determined after 28 experimental days in the middle gut and rectum (RT). The apoptotic rate was analyzed qualitatively according to the intensity (high, medium, and low) of caspase-3 immunostaining in epithelial cells. Performance parameters were not affected by the inclusion of NF in the diets. Juveniles fed 20% and 30% of NF showed a lower number of goblet cells containing sulfomucins than juveniles fed 0% and 10% of NF ( P = 0.01) in the RT. In the last segment of the middle gut (S2) and RT, the intensity of caspase-3 immunostaining in enterocytes was inversely related to the concentration of NF added in the diet. The inclusion of 20% and 30% of nutraceutical food in the diet of P. mesopotamicus reduced the rate of apoptosis and the number of goblet cells containing sulfomucin in the last intestinal segments of juveniles subjected to high stocking density, mitigating the effects caused by the adverse condition and being, therefore, beneficial for intestinal health.