U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Date of this Version


Document Type



Published in Beef Research Program Progress Report (1985) No. 2: 41-43


Little information is available on breed differences and variation in testicular development of young beef bulls. Larger testis size in young bulls is favorably correlated with sperm output, age at puberty, mature testicular size, and pregnancy rate. If testicular size is to be considered in selection programs for young sires, the breed differences, heritabilities, and relationships of testicular measurements to age and body weight must be established for young beef bulls.

The objectives of this study were to measure and define breed differences and variations in testicular size of yearling beef bulls, determine the heritability of yearling testicular size, and to examine the relationships between testicular size and age, growth traits, and age-of-dam effects in yearling beef bulls.