Use of protected forms of sodium butyrate benefit the development and intestinal health of Nile tilapia during the sexual reversion period

The aim of the present study was to verify the effect of sodium butyrate in protected and unprotected forms at two different concentrations of diet inclusion (0.25% or 0.5%) on the digestive enzyme's activity, integrity and structure of the intestinal tract and liver, in juveniles of Oreochromis niloticus, during the period of sexual reversion. In the experimental period, 3150 newly hatched post-larvae were randomly distributed in 21 experimental units of 100 L, divided into six treatments and one control, with three replicates each. The treatments were: fish fed with feed without supplementation (Control); fed with pure Na-butyrate (Pure 0.25% and Pure 0.5%), fed with palm oil-protected Na-butyrate (Oil 0.25% and Oil 0.5%) and fed with protected Na-butyrate with buffer solution (Buffer 0.25% and Buffer 0.5%). At the end of the experimental period, a decrease in alkaline protease activity was observed in the Oil 0.25%, Oil 0.5% and Buffer 0.5% groups when compared to the control. Fish fed Buffer 0.5% supplemented diet for 28 days had a longer length, perimeter and villus area of the anterior region of the intestinal tract when compared to Pure 0.25%. The Control, Pure 0.25% and Oil 0.5% groups had a reduction in villus width when compared to the other groups. In the posterior region, the group Oil 0.25% had a longer villus length when compared to the Pure 0.25% and Control, in addition to a greater area of villi when compared to the same groups and also to the Oil 0.5%. In this same intestinal portion, the Buffer 0.5% presented greater perimeter of intestinal villi when compared to the Control and Pure 0.25%. The Pure 0.25% and Buffer0.25% presented higher number of goblet cells per villi when compared to Oil 0.5%. The control group and those supplemented with sodium butyrate, in the different concentrations and forms, presented the intact intestine and without the presence of lesions. Regarding the liver, the Pure 0.5% group presented the highest macroesteatosis indexes when compared to the Control group, besides a higher necrosis index when compared to the Pure 0.25%. Thus, it can be observed that the supplementation of protected forms of sodium butyrate in the diet of juvenile Nile tilapia during the period of sexual reversion was effective in maintaining intestinal health, because Oil 0.5% contributed to the intestinal health of the animals, and the Oil 0.25%, Buffer 0.25% and Buffer 0.5%, increased the development of the intestine.