Management Factors Affecting Puberty in the Heifer

Abstract

The intricate changes in endocrine function during sexual maturation in the heifer are slowly being elucidated through basic research endeavors. Understanding the hypothalamic-pituitary-gonadal axis of the pre-, peri- and postpubertal bovine female will be of great benefit in developing management techniques that impact on age at which puberty occurs. Age at which heifers reach puberty is influenced by the breeds of the sire and dam used to produce replacement heifers. Because puberty is such a highly heritable trait the use of sires and dams which reached puberty earlier in life would result in an earlier age at puberty in replacement heifers. Brahman heifers exhibited a definite seasonal variation in sexual activity as measured by presence of corpora lutea and size and tone of the uterus. Sexual activity increased during the spring and was highest during the summer. Responsiveness of heifers to potential pheromonal cues from bulls appeared to be dependent upon body weight of heifers.