Reproduction 101: Basics of Breeding Cows and Heifers

摘要

Normal reproduction in the cow depends on interaction among several hormones, especially estrogen and progesterone, which are both produced by the ovary. Estrogen is created by maturing follicles and regulates the development and function of much of the reproductive tract. Estrogen is the hormone that triggers onset of heat (estrus). Progesterone is the predominant hormone between heat cycles and during pregnancy. It is responsible for and necessary for continuation of pregnancy once an embryo establishes itself in the uterus. Progesterone stippresses further development of follicles in the ovary and, thus, thwarts production of estrogen.