The objective of this study was to determine the relationship between calving year and season, parity, number of AI, day of lactation, milk production in the 1st 100 lactation days or diseases occurrence (retained placenta, endometritis or cysts), sperm motility (SM) during 30, 60 and 90 minutes of the cervical mucus survival test, cervical mucus crystallization (CMC) and their infl uence on days to fi rst insemination (interval), open days (SP), inseminations number for pregnancy (index), and pregnancy rates (PR) in Holstein cows (n=284). Signifi cant differences of interval, SP and index were detected also in relation to number of AI and day of lactation (P < 0.001). Cows without reproduction diseases (healthy) had better results of interval, SP (P < 0.01), index and PR. Pregnancy rate of healthy cows was by 11.43% higher, but without statistical signifi cance. The higher results of PR (62.74%) were discovered in relation
to ferny-like crystallization of cervical mucus (P < 0.001). CMC affected results of cervical mucus survival test, the highest motility of sperms after the 60 and 90 minutes was assumed in the case of club moss – ferny (14.80% and 7.96%) and ferny-like crystallization (13.82% and 8.47%) with statistical signifi cance (P < 0.05). The choice of these characteristics and defi nition of their relations allows assuming their using for detailed study and determination of the
cows´ biological ability to conceive, the one of the main components of effi ciency of cows´ reproduction.
