ABSTRACT
An increased emphasis on decreasing generation intervals due to genomic selection
has greatly influenced the management of bulls at AI organizations. Before genomics,
the genetic value of an AI sire was determined by examining the phenotype and production
traits of his daughters (i.e., proofs), and the minimum age at which sires were debuted
to the industry (proven) was approximately 4 to 4.5 yr of age. Currently, one decade
after the introduction of genomics to the industry, unproven, genomically tested sires
between 1.5 and 4 yr of age account for half or more of AI unit sales for most major
AI organizations. Accordingly, bulls destined for AI use receive optimum care and
nutrition from birth, and there is a renewed interest in examining endocrine modulation’s
role in puberty attainment and testicular development in bulls. In practice, hastening
puberty in bulls can be used concurrently with modern techniques of oocyte collection
in prepubertal heifers to minimize generation intervals in cattle, thus increasing
the rate of genetic advancement. The use of young genomic bulls will likely increase
or remain stable in the future, and accordingly, AI organizations will continue to
focus on optimizing bull management to ensure top tier genetics are available to the
industry.
Key words
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Article info
Publication history
Accepted:
September 4,
2018
Received:
July 5,
2018
Footnotes
The author declares no conflict of interest.
Identification
Copyright
Copyright © 2018, American Registry of Professional Animal Scientists. All rights reserved.