Читать книгу Bovine Reproduction - Группа авторов - Страница 358

Overall, body growth and development of the reproductive tract occur in an asynchronous pattern. For example, the ovaries grow at a rate 2.7 times faster than the body until puberty, whereas the tubular reproductive tract grows at about the same rate as body growth until about six months of age, and then enters a period of accelerated development until puberty [28]. No ovarian follicles are macroscopically visible at birth, but their numbers increase to maximal at four months, decrease through eight months of age, and remain relatively constant thereafter [28]. Growing and antral follicles increase in number during the first three to four months of age, which corresponds to the transient increase in circulating LH concentrations observed during that time period [29].

Height of the luminal epithelium of the tubular reproductive tract is stimulated at birth but regresses by one or two months of age. Thereafter, increases in height of epithelia are most rapid after six months. From this information it is concluded, at least for Holstein heifers, that rapid peripubertal growth of the reproductive tract commences during the seventh month and is largely terminated by 10 months of age [28].