Relationship between certain physical properties of cervical mucus and fertility in cows.

The object of the present investigation was to determine several physical properties of cervical mucus in spontaneous oestrus cows in relation to fertility. Because, it is very difficult to determine the exact time of the beginning of oestrus in cows, the aim of the present study was to investigate if physical properties of cervical mucus at the time of artificial insemination (AI) are related to conception or not. A total of 93 cows of Friesian breed were used. The animals exhibited spontaneous oestrus, without being submitted to any hormonal treatment. Samples of cervical mucus were collected 5-30 min before AI and pH, viscosity, spinnbarkeit (spinability), crystallization and penetration were measured. Pregnancy diagnosis was performed by rectal palpation 3 months later. The results obtained from cows that conceived (44 animals), compared to those obtained from cows that did not conceive (49 animals), were the following: a) viscosity had been significantly lower (p < 0.05), b) crystallization had been significantly higher (p < 0.05), and c) pH, spinnbarkeit and penetration of spermatozoa into cervical mucus did not differ. In conclusion, the best time for AI is when viscosity is below 20 mm H2O and crystallization is above 3. Viscosity and crystallization could be related to ovulation time, but this needs further investigation.