Influence of age and scrotal circumference on breeding soundness examination of range rams

Breeding soundness examinations (BSE) were conducted on 3,167 range rams on New Mexico sheep ranches during 1982, 1983 and 1984. Age and scrotal circumference (SC) were recorded for each ram and based on SC, rams were further classified as small (<30.8 cm), medium (31-37 cm) or large (>37.8 cm). Scrotal circumference increased with age (P < 0.05) up to 7 yr of age. Rams rated as satisfactory by BSE had a large (P < 0.05) SC, averaging 34.4 cm for all ages combined. Most rams classed as small (P < 0.01) were also rated unsatisfactory. There was no difference (P > 0.10) in BSE rating of rams classified by SC as medium or large. Results of this study suggest that SC is influenced by age, and this trait should be considered within age groups. Rams with an SC of <30 cm are more likely (P < 0.05) to be rated unsatisfactory by BSE.