Yearling scrotal circumference prediction equation and age adjustment factors for various breeds of beef bulls

Abstract

Scrotal circumference measurements and other data were collected on 4,218 Angus, Red Angus, Brangus, Charolais , Gelbvieh, Hereford, Polled Hereford, Limousine, Salers, and Simmental bulls born in the spring of 1991. All were participants in selected on-farm and central bull tests. Our objectives for the study were to develop 205-and 365-day age-adjustment factors for scrotal circumference and derive a 365-day scrotal circumference prediction equation based on adjusted 205-day scrotal circumference. We determined that a 205-day scrotal circumference of approximately 21 cm is necessary to reach 32 cm at 1 year. Age-of-dam adjustment factor for 205-day scrotal circumference is +.8 cm for 2- and 3- year-old dams. The factor for 365-day circumference is +.6 cm for 2-year-old dams.