This experiment was conducted to evaluate increasing levels of mannanoligosaccharides (MOS) in the diet of Nile tilapia larvae (Supreme®) at the sex reversal stage for 30 days. Nile tilapia larvae (n = 1500, p = 0.01 ± 0.001 g), were randomly distributed in 30 tanks of 100 liters each, for 30 days. The fish were distributed in a randomized design with six treatments and five replicates. The control diet (no MOS) was elaborated to contain approximately 35% of crude protein and 3,100 kcal DE/kg. Mannanoligosaccharides were included in the other diets, replacing corn, at levels of 0, 0.15, 0.30, 0.45, 0.60 or 0.75%. Linear increase in the intestine length, intestinal villous height and villi density was observed with the dietary MOS increase. No differences in body composition, weight gain, final weight, final length, condition factor, survival rate or number of goblet cells of the gut of the larvae were observed. A quadratic effect on feed conversion ratio was observed with the MOS inclusion and the best value was estimated with 0.34%. Dietary MOS inclusion at 0.34% improves feed conversion and increases intestine length, villi height and density of intestinal villi in diets for Nile tilapia larvae.
fish; intestinal morphology; performance; prebiotic
