The pH of the bovine cervical mucus was determined with pH test strip introduced into the cervical canal immediately before insemination in the estrous stage. For 5 years, 82 of the 242 cases examined became pregnant. The pH in the estrous stage were distributed widely from pH 6.0 to pH 7.8. The cases with pH 6.8 were most frequent and then pH 6.6, pH 6.4 and pH 7.0 followed it in this order of frequency. The average of the pH values was pH 6.69±0.28. The pH of the mucus in which the cow became pregnant were distributed from pH 6.0 to pH 7.2. The cases with pH 6.8 and pH 6.6 were equally frequent and then pH 6.4 and pH 7.0 followed them. The average was pH 6.66 ±0.26.
According to the fiscal year or season, the pattern of the pH distribution showed some variation. However, the cases with pH 6.4 to pH 7.0 were always predominant. In relation to the age or the times of calving, the cases with pH 7.0 and pH 7.2 were relatively many in the heifers. There were found in relatively many cases in which the pH showed 6.6 after first to third times of parturition, and 6.4 above 4th parturition.

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Various doses (0 to 50 i.u.) of gonadotrophins were examined for effect on ovulation in adult rats. A total of 600 rats were used in the schedule of experiment, as shown in Fig. 1.
The results obtained are summarized as follows.
1. When rats pretreated with 50, 30, 20, or 10 i.u. of pregnant mare serum gonadotrophin (PMS) were injected with same dose of human chorionic gonadotrophin (HCG) 20 hours prior to sacrifice, the maximum number of ova ovulated by them was 43.9, 31.2, 21.8, or 16.3 per rat, respectively. When rats were killed after treatment with 50, 30, 20, or 10 i.u. of PMS alone, it was found that the average number of ova ovulated (by the number of rats ovulated in parentheses) was 1.0 (1/10), 2.0 (3/10), 6.5 (4/10), or 12.1 (9/10), respectively.
2. The percentage of ovulated rats and the number of ovulated ova were reduced with a decrease in the dose of HCG. This tendency was notable when rats had been treated with a lager dose of PMS and a small dose of HCG (below 1/2 or 1/3 of the dose of PMS).
3. Superovulation-treated rats showed a complete ovulation a few hours later than untreated control rats. The percentage of ovulated rats and the number of ovulated ova, however, increased with the lapse of time after HCG treatment. A complete ovulation was delayed a little in rats treated with a small dose of PMS.
4. The results mentioned above suggest that it may be necessary for the induction of superovulation in adult rats to inject with such dose of HCG as corresponding to about 1/2 (or least 1/3) of the dose of PMS.

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Induced parturition by the use of prostaglandin F_2α (PGF_2α) was investigated in cattle. Thirteen animals including 3 cows at 116159 days of gestation (group A), 3 cows and 2 heifers at 252258 days of gestation (group B), and 2 cows and 3 heifers at 272276 days of gestation (group C), received either an intrauterine injection with PGF_2α dissolved in saline, or an intramuscular injection with PGF_2α suspended in propylene glycol. Estriol, each daily dose of 50 mg, was injected intramuscularly 1 to 3 times between one day before and one day after PGF_2α treatment in 7 animals. Concentration of progesterone in blood plasma collected from jugular vein following the treatment was determined in 4 animals, by a radioimmunoassary method.
In group A, a total amount of 25 mg PGF_2α was infused in 3 times into the slit between the endometrium and fetal membrane of the gravid uterine horn at 6-hour intervals. One of them was given an additional 10 mg PGF_2α, 21 hours later. Abortion was induced in all cows 51, 79, and 91 hours after the first PGF_2α infusion, respectively. In group B, 2 cows and 2 heifers received 3 intrauterine infusions with a total amount of 2030 mg PGF_2α, at 912-hour intervals. Two of them were given an additional 10 mg PGF_2α, 26 and 31 hours later, respectively. Parturition in 2 animals given the additional treatment was induced 91 and 108 hours after the first treatment, and in 2 other animals 39 and 58 hours, respectively. In the remaining one heifer which was injected intramuscularly with 10 mg PGF_2α, and an additional 10 mg, 69 hours later, parturition was induced 118 hours after the treatment. In group C, 2 heifers received a single intramuscular injection with 10 mg PGF_2α, and an another heifer and a cow were injected intramuscularly with a total amount of 15 mg PGF_2αdivided at 3-hour interval. The remaining one cow received 2 intrauterine infusions with a total amount of 20 mg PGF_2α, at 12-hour interval. Parturition was induced in all animals between 2953 hours after the treatment. It is considered that the shorter the interval between the treatment and the expected calving date, the easier is the induction of parturition. In one of 5 animals in group B, and 3 of 5 animals in group C, dystocia in more or less extent was observed. However, all of the calves were alive when they were born. Fetal placentae were retained for 26 days in all animals in groups B and C. Progesterone levels in peripheral blood plasma dropped sharply following the PGF_2α injection, from 3.55.3 ng/ml prior to the treatment to 1.32.0 ng/ml at the time of 612 hours after the treatment. When the plasma progesterone levels had maintained as low as 1 ng/ml or less for some time, the cervical canal dilated completely as large as five fingers width. These results indicated that the essential role of PGF_2α in the induced parturition should be its luteolytic action.

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Prostaglandin F_2α (PGF_2α) and two synthetic LH-RH preparations; i.e. pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH₂ (LH-RH) and its analog [Des-Gly-NH₂¹⁰, Pro-ethylamide⁹]-LH-RH (LH-RH-I), were used for the estrous synchronization in the grazing cows, and the occurrence of estrus, ovulation after the treatments and the fertility at the first synchronized estrus were investigated.
A total of 61 cows (48 Holstein and 13 Japanese Shorthorn) in the luteal stage of the estrous cycle were alloted to three experimental groups; i.e. Group A including 16 cows received a single intrauterine infusion of 3 mg or 4 mg of PGF_2α and an intramuscular (i.m.) injection of 200 μg of LH-RH, Group B including 13 cows received the same PGF_2α treatment as in Group A and an i.m. injection of 200 μg of LH-RH-I, and Group C including 32 cows received the PGF_2α treatment alone. Each dose of PGF_2α dissolved in 0.75 ml or 1.0 ml of aq. distillata was deposited through the cervix into the uterine horn ipsilateral to the corpus luteum. LH-RH and LH-RH-I preparations dissolved in 5.0 ml of aq. distillata was injected during the period between 52 and 56 hr after the PGF_2α treatment.
Estrus occurred in 10 (62.5%) of 16 cows in Group A, 10 (76.9%) of 13 cows in Group B and 26 (81.3%) of 32 cows in Group C during the period of 3772 hr after the PGF_2α treatment. Estrus did not occur during the period of 73108 hr in all cows of three groups except two (6.2%) in Group C. Quiet ovulation was observed in 6 cows (37.5%) in Group A, in 3 cows (23.1%) in Group B and in 1 cow (3.1%) in Group C within 132 hr after the treatment. The remaining 3 cows in Group C exhibited estrus between the period of 11 and 15 days.
Ovulation occurred in 12 (75.0%) of 16 cows during the period of 7396 hr in group A, in 11 (84.6%) of 13 cows during the period of 6184 hr in Group B and in 17 (58.6%) of 29 cows during the period of 85108 hr in Group C. The interval elapsing from the treatment to the time that ovulation being detected in more than 80% of cows in Group A and B were shortened by 24 hr and 12 hr, respectively, as compared to that in Group C.
In the cow that exhibited behavioral estrus, the conception rates were 66.7% (6 of 9 cows) in Group A, 60.0% (6 of 10 cows) in Group B and 75.0% (21 of 28 cows) in Group C by the insemination during 35 days of the post treatment period. Whereas, the cow which occurred quiet ovulation in Group A, B and C conceived in 0 of 4, 1 of 3 and 1 of 1, respectively.
These results suggest that an intramuscular injection of synthetic LH-RH preparations following an intrauterine infusion of PGF_2α during the luteal stage of the estrous cycle may be applicable to the synchronization of ovulation in cows. However, the cause of the occurrence of quiet ovulation and the low fertility of the cow which showed dull estrus followed by the treatments must be futher-more investigated.

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The number, size and distribution of follicular cysts (cysts), and coexistence of corpora lutea in 91 dairy cows with cystic ovaries were examined by rectal palpation. Eighty cows were treated with an intramuscular injection of 2040mg of betamethasone or 1020mg of dexamethasone, 9 with 10, 000 MU of HCG with or without simltanious treatment by manual rupture of cysts, and 2 with the manual rupture only. Serum concentrations of progesterone and estadiol-17β were determined by RIA. Relationships between these hormone levels and ovarian conditions as well as prognosis following the treatments were investigated, and results obtained were as follows.
1. Conception rates following the corticoid injection, HCG injection, and manual rupture were 65/80, 7/9 and 2/2, respectively.
2. Cysts were detected in the left ovary of 16 (17.6%) cows, in the right ovary of 35 (38.5%) cows, and in both ovaries of 40 (44.0%) cows. There was no relationship between distribution of cysts and patterns of estrous behavior, as well as conception rates after the treatments.
3. Multiple cysts, more than 3, were found in 11 of 27 (40.7%) cows with nymphomania or continuous estrus, 4 of 31 (12.9%) cows with irregular estrus and 6 of 33 (18.3%) cows with anestrus. No difference was observed in conception rates among the patterns of estrous behavior.
4. Large cysts, more than 3 cm in diameter, were found in 33.3% of cows with nymphomania or continuous estrus, 25.8% of cows with irregular estrus, and 42.4% of cows with nestrus. Considerably higher conception rate was obtained in cows having large cysts as compared with in cows with cysts smaller than 3 cm in diameter.
5. Reciprocal correlation, but not significant, was observed between total volume of cysts which was calculated in each cows from the diameter and number of cysts, and serum concentrations of progesterone and estradiol-17β.
6. Corpora lutea were found in 37 of 91 (40.7%) cows. However, serum concentration of progesterone was not different between cows with coexistent corpora lutea and cows with follicular cysts only. Cows with no corpus luteum showed considerably higher conception rate as compared with that of the others.
7. Manual removal of cysts was tried in 81 cows. All the cysts in 31 (38.3%) cows were ruptured, while no cysts in 33 (40.7%) cows. In remaining 17 (21.0%) cows, some cysts in each cow were ruptured and the others were not. There were no differences in serum concentrations of neither estradiol-17β between the cows whose cysts were all ruptured and those some or all cysts were not ruptured. Conception rate was higher in cows with wholly rupturable cysts than in those with cysts which were unable to rupture.
8. There was no significant correlation between the condition of follicular cysts and the postpartum intervals.
From these findings it may be concluded that there was no obvious correlation between the condition of follicular cysts examined per rectum and serum concentrations of progesterone and estradiol-17β, and that the size of cysts and fragility against the treatment of manual rupture with reference to the prognosis of cystic ovaries. The number of cysts may have a possible relationship to the patterns of estrous behavior.

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Synchronization of the estrous cycle with prostaglandin F_2α in mares was examined between March and May 1974 on Breton and Percheron mares except one Anglo-arab in the National Tokachi Livestock Breeding Farm, Hokkaido. All mares were given 4 or 5mg of prostaglandin F_2α intramus-cularly, on day 3 to 11 after previous ovulation.
Results obtained were summarized as follows:
1. Fourteen out of 17 mares (82.3%) came into estrus on day 2 to 5 and ovulation were confirm-ed by rectal palpations on day 10 following treatment in the 14 mares.
2. Serum progesterone concentrations of 5 mares determined by radioimmunoassay, decreased abruptly on the first day of treatment in 4 mares, declining below 1.0 ng/ml on day 3 after treatment and estrus were observed at this time.
In the 14 mares showed estrus with prostaglandin F_2α injection, side effects such as profuse sweating, rises in vermicural intestinal movements and slight colitis were observed temporarily, whereas no side effects were observed in 3 mares failed to induce estrus.

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