EN
The objective of the examinations performed on 54 sows weaned after 5 weeks lactation (one technological group) in an industrialized farm from April to September 1992 was to establish resistance of vaginal mucus at oestrus after 4—7 days from weaning, 19—22 days after mating, at the 110th day of pregnancy and at the 28th day of lactation. The examination method of vaginal mucus resistance is in 80—90% in accordance with the physiological state of sows. The resistance of vaginal mucus at the 4th day after weaning is only slightly correlated with that at 19—21st day of pregnancy. The age of the sows (a consecutive reproductive cycle) does not significantly affect the differences in vaginal mucus resistance after weaning.