EN
The investigations concerned the influence of ivermectin on the biological value of the sémen of boars. The quality of the semen was evaluated on the basis of a preliminary estimation of spermatozoa concentration in ejaculates, the percentage of spermatozoa mortality and the morphological picture of spermatozoa. The aim of the study was also to estimate a fecundating value ot the semen by determining the percentage of sows which repeated oestrus after 21 days from insemination with the semen of the experimental boars. A decrease in spermatozoa survival within two weeks after the administration of ivermectin was found.