Chemical properties of bovine cervical mucus during normal estrus and estrus induced by progesterone and/or PGF2 alpha

Ninety-two Friesian cows were used to determine the chemical properties of cervical mucus during normal estrus and estrus induced by progesterone (P-4 )-releasing intravaginal devices (PRID) and/or prostaglandin F2 alpha. The animals were assigned to 4 groups (no treatment, a PRID for 12 days plus in jection of 1000 IU PMSG at the removal of PRID, a double im injection of PG F(2 alpha) 11 days apart, or PRID for 7 days plus an im injection of PGF(2 alpha) 24 h before the removal of PRID). A number of cows with normal estru s exhibited three consecutive estrous cycles after delivery. Cows that had not shown estrus for 3 months after delivery had their ovaries palpated twi ce at 10-day intervals, to determine their ovarian activity. Then PRID and/ or PGF2a was administered in cows that had a palpable corpus luteum in one of the two palpations (cyclic cows). A double artificial insemination (Al) was performed to the cows of the three induced-estrus groups, while the cow s with normal estrus received only one Al. Cervical mucus samples were coll ected from all cows 5 to 30 min before the first Al. Additionally, samples of cervical mucus were collected from 20 cows during their first estrus aft er the induced one. The results are summarized as follows: 1) The biochemical properties of cer vical mucus in the first three estrus periods after delivery were similar. 2) These properties were similar both in normal estrus after delivery and i n the first estrus after an induced one. 3) Glucose and fructose concentrat ions for normal estrus were similar to those for induced estrus groups. 4) Total protein and cholesterol concentrations were significantly lower (P < 0.001) in normal than in induced estrus, while no difference was found amon g the induced estrus groups. 5) Pregnancy rates of the cows did not differ significantly among the normal and the induced-estrus groups. 6) The percen tages of cows in the induced-estrus groups that produced cervical mucus wit h total protein and cholesterol concentrations similar to those for the nor mal estrus groups was very low. (C) 2001 by Elsevier Science Inc.