U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


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Date of this Version



Published in J. Reprod. Fert. (1972) 28, 285-289


Follicle-stimulating hormone from different species has been used to increase ovulation and calving rates in cattle, injections proving to be most successful when given during the late follicular phase of the oestrous cycle or in combination with progestagens (Willett & Buckner, 1953; Bellows, Anderson & Short 1969). Some investigations have resulted in substantial increases in ovulation and calving rates, but there is usually a high degree of variation in ovarian response. Patterns of follicular growth and atresia have been studied in cattle (Rajakoski, 1960) and hypotheses have been suggested to explain how exogenous FSH stimulates follicle growth in relation to normal stages of growth and atresia (Schilling & Holm, 1963).

There are no investigations on histometric evaluation of follicular development after FSH treatment. The purpose of this study was to determine follicular response after constant infusion of FSH from different species sources and to evaluate variation in follicular response among heifers when a constant level of exogenous FSH is maintained in the systemic circulation during late pro-oestrous.