The Oestrous Cycle of the Cow: Hormonal Parameters and Time Relationships Concerning Oestrus, Ovulation, and Electrical Resistance of the Vaginal Mucus

Abstract

A synopsis is presented of hormonal profiles (peripheral plasma values of LH, FSH, progesterone; urinary oestrogens) during the oestrous cycle of cattle. After ovulation (day one) progesterone levels begin to increase from about day 4, reach a plateau around day 10, and decrease to basal concentrations starting on days 17 to 18. Corresponding with the progesterone decrease, urinary oestrogens show a main increase reaching its maximum one day before ovulation. LH levels are fairly constant from ovulation until day 5, small but significant peaks can be observed between days 6 and 10 in some cows (6 out of 21) and levels then decrease from day 11 to 13. A gradual additional increase begins on day 17, resulting in the preovulatory LH peak 25.7 ± 6.9 h (n = 75) before ovulation. This peak has a duration of 7.4 ± 2.6 h (n = 89) and occurs any time of the day but preferentially around 8 a. m. and 8 p. m. respectively. Likewise related are the two main periods for ovulation. During oestrus, (average duration of 16.9 ± 4.9 h (n = 28) the electrical resistance of the vaginal mucus decreases and the lowest values always correspond with the LHpeak. FSH levels show a wavelike pattern with peaks around days 4, 8, 12–13, 17, 18 and also coinciding with the pre-ovulatory LH peak. The sharp decrease in FSH between the two peaks on days 17 and 18 correlates with the decrease of progesterone during luteolysis. Obviously there is a parallelism between FSH elevations and follicular growth (determined by means of pelviscopic observations).

Behavioral and hormonal pattern of repeat breeder cows around estrus

“…The sequence and time relationships among the various endocrine/ovulation events in this study were also consistent with most of the related data published thus far (Schams et al 1977, Dieleman et al 1986, Larsson 1987, Rajamahendran et al 1989, Stevenson et al 1998, Saumande & Humbolt 2005, but there were some exceptions. In seven CTRL and five RB cows, the E 2 peak preceded estrus onset and, in four CTRL and four RB cows, the LH peak preceded the E 2 peak.…”

Plasma progesterone and gonadotrophin concentrations and ovarian activity in post-partum dairy cows

“…The results reported here indicate that there is an LH surge before the elevation of plasma progesterone above basal concentrations during the post-partum period in the dairy cow. The time relationship between the occurrence of this LH surge and the increase in progesterone (4-5 days) is similar to that in the normal cycle (Schams et al, 1977) and supports the view that this progesterone comes from the ovary; developing follicles are the most likely source because no corpora lutea were palpated at this time.…”

Prediction of bovine ovulation by a rapid radioimmunoassay for plasma LH

“…For example, in 2 heifers, the first significant plasma LH rise appeared before the beginning of oestrus (-8 and -3 h) while in all the other animals the LH peak followed the start of oestrus (0-9 h). These observations reflect those of Hansel & Echternkamp (1972), Schams et al (1977), Chenault et al (1975) and Fietta, Olson & Gass (1968) who have shown that the LH peak can follow oestrus and those of Swanson & Hafs (1971) and Christenson et al (1975) who observed oestrus after the LH peak. The interval between the beginning of oestrus and ovulation is long in the cow, ranging from 16 to 36 h (Gerasimova, 1940) or 16 to 42 h (Swanson & Hafs, 1971).…”

“…The mean interval obtained between the beginning of the LH surge and ovulation (27-3 ± 1-6 h) agrees with those reported by Henricks & Dickey (1970) and Chenault, Thatcher, Kalra, Abrams & Wilcox (1975) but is smaller than those reported by Schams, Schallenberger, Hoffmann & Karg (1977), Christenson et al (1975) and Swanson & Hafs (1971). This discrepancy may be explained by the fact that these authors used rectal palpation at long intervals (4-6 h) for determination of the moment of ovulation.…”