Induced ovulation and fertility in prepuberal cattle, sheep and swine.

DEVELOPMENT of the reproductive system takes place throughout the prepuberal period, and may continue after puberty until full sexual maturity is reached. Some researchers consider that the onset of puberty is marked by full behavioral symptoms of estrus, particularly acceptance of the male, whereas others consider ovulation as the well-defined beginning of puberty. We will consider puberty to be initiated by the occurrence of both phenomena, as both events are minimal requirements for conception to take place naturally. Thus, the female at puberty has the ability to conceive but not necessarily to fully reproduce. Ideally, to determine how much puberty may be advanced experimentally, untreated control groups should be included which are allowed to reach puberty under the same environmental conditions. However, much of the information on responsiveness of immature females to exogenous hormone treatment has resulted from experiments with different objectives, and comparisons often must be made with the ages or weights at which the same species is expected to reach puberty naturally. Therefore, brief consideration of prepuberal development is included.