EN
The experiment studied 32 crossbred fatteners. The animals were fed in a two-stage system with the addition of feed antibiotic (control group - C) or prebiotic BIO-MOS (Saccharomyces cerevisiae, strain 1026; 0.1% during the first period of fattening) (experimental group - E). From 16 animals chosen at random (8 fatteners each from groups E and C) the following sections of small intestine were sampled post mortem and preserved for histological, histochemical and immuno-histochemical evaluation: duodenum, jejunum and ileum. Staining by the review (H-E) and paS-Alcjan method was carried out. Antibodies bax, bcl-x, bcl-2 and PCNA and Ki-67 were used to evaluate apoptosis and proliferation. The preliminary studies in situ revealed the suitability of the employed antibodies: bax, bcl-x and bcl-2 in evaluating apoptosis. Histological, histochemical and immuno-histochemical evaluation of the mucosa in the small intestines of the animals receiving feed antibiotic or its replacer - prebiotic, showed that the effect of the employed additives differentiated in terms of morphological traits, apoptosis and proliferation abilities of crypts’ epithelium. It was concluded that there were no negative effects of BIO-MOSS on the mucosa of the small intestine in fatteners.