The temporal relationship between the preovulatory estrogen peak and the optimal mating period in rhesus and bonnet monkeys

R. F. Parkin, Andrew G Hendrickx

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The optimal mating period was determined for rhesus (Macaca mulatta) and bonnet monkeys (Macaca radiata) using the preovulatory estrogen peak as the point of reference. Blood samples were drawn twice daily and total plasma estrogens were determined by rapid radioimmunoassay. The animals were mated before, at or after the estrogen peak. Of the four rhesus monkeys that conceived during the study, two were bred 12.5 h post estrogen peak. The precise temporal relationship between the estrogen peak and breeding could not be determined for two of the rhesus monkeys; there is, however, good evidence that breeding occurred within 18 to 24 h post estrogen peak. Fertile matings in four bonnet monkeys occurred at 8.0 h pre peak and 7.5, 12.0, and 12.5 h post peak. The optimal mating period for both macaque species appears to be limited to an approximately 24 h period at and immediately after the estrogen peak. The temporal position of the preovulatory estrogen peak in relation to the fertile period of the menstrual cycle makes it an excellent indicator for use in detecting an impending fertile period. The apparent brevity of the optimal breeding period and its occurrence 24 to 36 h prior to the reported time of ovulation suggest temporal relationships regarding breeding, ova and sperm transport, gamete viability, and fertilization which were previously unknown.

Original languageEnglish (US)
Pages (from-to)610-616
Number of pages7
JournalBiology of Reproduction
Issue number5
StatePublished - 1975


ASJC Scopus subject areas

  • Cell Biology

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