ABSTRACT:The effect of feed additives: antibiotic (group C), probiotic (group E1) and prebiotic (group E2) on the results of fattening and selected slaughter and pork meat quality traits of two genotypes of pigs (PLW × PL) × BL and (PLW × PL) × Dur, gilts and hogs, was determined. The results obtained for the examined traits in the feeding groups under comparison were slightly differentiated. The growth rate and feed conversion differed between the genetic groups in favour of crossbred fatteners with the proportion of Dur breed (P ≤ 0.01). The mean backfat thickness from 5 measurements and loin "eye" area in fatteners derived from Dur sires as compared to hybrids coming from BL sires were significantly lower (P ≤ 0.01) while the length of carcass was higher (P ≤ 0.01). The gilts were characterized by better meatiness than boars: loin "eye" area, loin weight without backfat and skin, ham weight without backfat and skin differed on the level of P ≤ 0.05, and meatiness of carcass and meatiness of basic cuts at P ≤ 0.01. Significant (P ≤ 0.05) or highly significant (P ≤ 0.01) differences in the proportions of acids: C 18:2 , C 18:3 , C 20:4 , C 22:4 and PUFA in the lipid fraction of MLD were found between the feeding groups. The proportion of the above-mentioned acids was lower in group E2 and higher in group E1 as compared to C. The proportion of the acid C 18:1 was significantly higher (P ≤ 0.05) in group E2 as compared to E1. The demonstrated differences indicate the need of further studies in this respect. In pig fattening there is a possibility of effectively replacing feed antibiotics with other additives. The application of biostimulators -probiotic Bactocell or oligosaccharide Bio-Mos instead of the antibiotic flavomycin appeared to be favourable. From the production aspect it seems to be justified to supplement the feed rations for fatteners during the first stage of fattening with feed additives from the group of probiotics or prebiotics.