By Ben Rogers, Operations Coordinator, GENEX
Genomics has accelerated genetic progress in dairy cattle. This technology has shortened the generation interval and enables producers to make strategic decisions about calves at a very young age. While genomics has brought forth changes on the farm, it has also been the driving force behind changes in the semen production and bull management processes at A.I. studs and semen production facilities around the world.
Young Sire Management
After genomics was introduced, the average age of sires in production facilities decreased by nearly half. This is noticeable today when paging through a sire directory. When progeny testing was the primary source for sire genetic evaluations, the useful life of a sire was about five years. Today it’s between two and three years.
How have A.I. studs had to adapt to these changes? The increased demand for semen from young, high genetic merit bulls has A.I. studs moving bulls into production centers at an earlier age. This is a delicate process with calves transported at or around weaning. This timeline can pose challenges, as it’s a vulnerable stage in a calf’s life. The potential for exposure to foreign pathogens during transport and the stress brought on by environmental changes simply adds to the challenges.
These younger bulls have required changes to facilities and animal care protocols as well. Staff have had to learn to care for smaller bulls in retro-fitted facilities originally built for much larger, mature animals. Additionally, these younger bulls consume less feed and bedding than mature bulls; however, work in the semen collection arena and young bull calf care has increased.
Semen Collection Changes
The usefulness of an outstanding sire is limited largely by the bull’s ability to produce enough semen to meet market demand before his genetics become obsolete. To maximize semen output from young genomic-proven bulls – and ultimately to best meet the genetic needs of members and customers – bull handling and collection procedures were updated.
Most bulls undergo an initial semen collection and evaluation once they reach about 1 year of age. To better accommodate these smaller-sized sires in the collection arena, A.I. studs have added smaller teaser animals. These animals are used as a stimulus to illicit mounting and ejaculation for maximum sperm harvest. Miniature beef breed steers have been found to be very effective for the job due to their small frame size and stability.
The size of the bull has led semen collection professionals to modify their procedures too. These individuals must get low enough to safely reach under the animal for an effective semen harvest.
The added work in the collection arena is also due to more collections per week from genomic-proven sires. It is difficult for younger bulls to match the amount of semen previously produced by older bulls. In fact, it takes approximately three young bulls to produce the amount of semen one mature bull can produce. More collections per week help to maximize output so more females can be mated to each genomic-proven sire.
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| With the introduction of genomics, A.I. Studs have altered many bull handling and semen collection processes to better accommodate smaller-sized sires. |
Laboratory Adaptations
A mature bull is capable of producing about 2,000 semen units per week, whereas a 1.5 year old genomic-proven bull is capable of producing about 500 units. With more collections needed to achieve harvest goals, semen processing labs have more ejaculates to evaluate and less units to process per collection.
The laboratory staff thoroughly evaluate the ejaculates for concentration, motility and percent of abnormal cells. While this evaluation is done on every ejaculate, it’s especially important for very young bulls as they can be prone to semen quality issues associated with underdeveloped reproductive tracts. These late maturation issues are more typical among Jerseys than Holsteins.
The increasing demand for high genetic merit bulls available in GenChoice™ sexed semen means labs are providing greater volumes of semen to be sex sorted too, delivering ejaculates to the sorters throughout the day. To maximize GenChoice™ semen production, extra staff are necessary in the lab and livestock areas so sires can be collected at all hours as needed. Genomics has been a driving factor for the increase in the sex-sorted product, greatly expanding the list of sires being sorted.
Keeping Up the Pace
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With genomics and the increased demand for semen from young,
high genetic merit bulls, A.I. studs are moving bulls into
production centers at an earlier age, at weaning or
around 70 days of age. |
With genomics and removal of the in-waiting period, the genetic merit of bulls is increasing at an exponential rate. Data from the last five sire summaries indicates one point of Lifetime Net Merit (LNM$) is gained every four days in the Holstein breed, and Cheese Merit (CM$) gains are similar for Jerseys. This shows just how fast genetic progress is being made and how important it is to carefully choose the bulls that come into stud.
As the rate of change accelerates in the bovine genetics industry, GENEX continues to refine processes for the ultimate in bull care and the production of high-quality semen. Focus is on managing change to ensure the semen produced meets the needs of today’s and tomorrow’s producers in terms of quality, fertility and genetic level.
