Physical properties of bovine cervical mucus during normal and induced (progesterone and/or PGF2 alpha) estrus

Ninety two Friesian cows were used to determine physical properties of cerv ical mucus collected during normal estrus and estrus induced. Estrus was in duced using either progesterone (P-4) releasing intravaginal devices (PRID) and/or prostaglandin F2 alpha (PGF2 alpha). The animals were assigned to 4 groups (no treatment, a PRID for 12 days plus an injection of 1000 IU PMSG at the removal of the PRID, a double injection of 3 mL PGF2 alpha 11 days apart, and a PRID for 7 days plus an injection of PGF2 alpha 24 h before th e removal of PRID). A number of cows with normal estrus exhibited three con secutive estrus cycles after calving. Cows that had not shown estrus for th ree months after calving had their reproductive system palpated twice at 10 -day intervals, to determine their ovarian activity. Then PRID and/or PGF2 alpha was administered to cows that were found to have a palpable corpus lu teum in one of two palpations (cycling cows). The cows of the three induced estrous groups were artificially inseminated (Al) twice, while those with normal estrus received only a single Al. Cervical mucus samples were collec ted from all cows 5 to 30 min before the first Al. Additionally, samples of cervical mucus were collected from 20 cows at their first estrus after the induced estrus. The results are summarized as follows: 1) The physical properties of cervic al mucus were similar in the first three normal consecutive estrus cycles a fter calving. 2) The physical properties of cervical mucus in normal estrus after calving were similar to those in the first estrus after an induced e strus. 3) The pH values for normal estrus were similar to those for induced estrus. 4) Viscosity of cervical mucus in the normal estrous group was sig nificantly lower than that in the induced estrus. Furthermore, significant differences were noticed among the three induced estrous groups. 5) Spinnba rkeit, crystallization and receptivity of cervical mucus (penetration test) were significantly higher in the normal estrous group than in the induced estrous groups, while no difference was detected among induced estrus group s. 6) Pregnancy rates in (C) 2001 by Elsevier Science Inc.