Implications of disparate uterine and ovarian development observed among heifers evaluated during the peripubertal period

The incidence and implications of disparate ovarian and uterine development during the peripubertal period were evaluated in two experiments. In Experiment 1, two consecutive pre-breeding evaluations were performed on 469 heifers. In Experiment 2, data from 22,174 heifers were retrospectively analyzed. For heifers in both experiments, ovarian and uterine maturity were independently assessed via transrectal evaluation, and a two-digit reproductive tract score (RTS: first digit = ovarian; second digit = uterine) was assigned. Measures of the physical maturity of heifers were recorded at the time of pre-breeding evaluation. Heifers were subjected to 14-day progestin-based protocols for synchronization of estrus, and artificial insemination (AI) was performed. Pregnancy diagnosis was performed via transrectal ultrasonography. Incidence of disparate ovarian and uterine score was 33.7 % (158/469) in Experiment 1 % and 16.3 % (3622/22,174) in Experiment 2. Observations of disparate ovarian and uterine maturity were correlated with physical maturity. Heifers with RTS