Nutritional Regulation of Precocious Puberty in Beef Heifers

Age at puberty has an important impact on the productive, reproductive and economic efficiency of female cattle. The occurrence of this physiological event implies an adequate growth rate and development of the animal that supports the endocrinological mechanisms that lead to sexual maturity. Age at puberty and first conception will influence lifetime productivity of cattle, reflected in the number of calves (Bagley, 1993). In spite of the importance of this physiological endpoint, the metabolic signals that activate the endocrine mechanisms that trigger puberty are still unknown. Puberty has been defined as the manifestation of reproductive competence, with the ability to ovulate an oocyte accompanied by the presentation of estrous behavior and the development and maintenance of a functional corpus luteum (Kinder et al, 1987). In cattle as well as other species, maturation of the reproductive axis occurs in a gradual fashion and is associated with changes in body composition and in the somatotropic axis that regulates metabolic status of the animal. While changes in the reproductive mechanisms that lead to puberty have been well established, metabolic signals that modulate the processes of sexual maturation are not well known.