Scrotal circumference measurements on young Holstein bulls

Scrotal circumference was measured on all young Holstein bulls entering an artificial insemination center over a 57-month period. A total of 3,008 measurements were taken on 723 bulls between the ages of 5 and 18 months. Mean scrotal circumference, standard deviation, and 10th and 25th percentile statistics were calculated for each one-month interval between 5 and 18 months of age. Scrotal circumference increased as a logarithmic function of age and was best described by a quadratic regression equation. This information provides the veterinary practitioner with indices for normal scrotal circumference measurements for young Holstein bulls, and an estimate of the scrotal circumference growth curve.