Publication Date:
1940-04-01
Description:
1. The length of oestrus in mares varied from 3 to 54 days, although in most cases it was 7–8 days.2. The length of dioestrus varied from 5 to 30 days, but in most cases was 11–16 days.3. Ovulation occurred in most cases on the last day of oestrus, but a considerable number of ovulations occurred on the 1st and 2nd days before the end of oestrus, and in a few cases from the 5th day before the end of oestrus to 1 day after the end of oestrus.4. Artificial insemination of mares was equally effective in the intervals of 24, 48 and 72 hr. before ovulation but was unsuccessful in intervals of 2 and 4 hr. after ovulation.5. Pregnancy was diagnosed in all mares by rectal palpation on the 23rd day and in one mare as early as the 16th day.6. The foetus developed in the opposite horn of the uterus to the ovary which ovulated at the onset of pregnancy in five out of seven mares.7. Ovulation occurred in one mare on the 23rd day of pregnancy.8. Gonadotrophic hormones had no effect when given in the anoestrous period (November to March).9. Ovulation was induced in 20–40 hr. in most cases after the intravenous injection of 1000–2000 mouse or rat units of pregnancy urine extract intravenously, provided a fairly mature follicle was present in the ovary at the time of injection.When this ovulation occurred, the duration of oestrus was shortened.
Print ISSN:
0021-8596
Electronic ISSN:
1469-5146
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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