Current Progressive Dairy digital edition

How genomics has transformed A.I. semen production processes

Ben Rogers for Progressive Dairyman Published on 29 June 2018
A.I. studs helped accommodate the smaller sized-sire

Genomics has been an incredible accelerator for genetic progress in dairy cattle.

Not only has it caused changes on the farm, but it has also been the driving force behind many changes in the semen production and bull management processes at A.I. studs and semen production facilities throughout the industry.



Young sire management

After the introduction of genomics, the average age of sires in the Genex production facilities decreased by nearly half. When progeny testing was the primary source for sire genetic evaluations, the useful life of a sire was about five years; with genomics, the typical useful life of a sire is now between two and three years.

How have A.I. studs adapted 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 weaning or around 70 days of age.

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.

This timeline can pose challenges from an animal care standpoint; it is already a vulnerable stage in a calf’s life, and the potential for exposure to foreign pathogens during transport and stress brought on by environmental changes adds to it.

These younger bulls have required changes in facilities and animal care as well. Staff have learned to care for smaller bulls in retrofitted facilities originally built for much larger, mature animals. The employees’ roles and responsibilities have changed, as the overall herd size has been reduced by about 40 percent.


The cost of animal care has decreased some with younger bulls consuming less feed and bedding than mature bulls and sires no longer standing “in waiting” for progeny test results; 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 herds’ genetic needs, bull handling and collection procedures had to be updated.

Bulls undergo their initial semen collection and evaluation once they reach about 1 year of age. One change to better accommodate these smaller-sized sires in the collection arena has been the addition of smaller teaser animals.

These teaser animals are used as a stimulus to elicit 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. With younger bulls, it is difficult 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 helps to maximize output so more females can be mated to each sire.

Laboratory adaptations

A mature bull is capable of producing about 2,000 semen units per week, whereas a year-and-a-half-old genomic-proven bull has the capability of producing about 500 units per week. With more collections needed to achieve their harvest goals, semen processing labs have more ejaculates to evaluate and yet less units to process per collection.

The laboratory staff thoroughly evaluates 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 in the Jersey breed than in Holsteins.

The high demand for high- genetic-merit bulls available in 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 sorted semen production, extra staffing is necessary in the lab and the livestock area 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

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, A.I. studs continue to refine their processes for the ultimate in bull care and the production of high-quality semen. Their 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.  end mark

PHOTO 1: With the introduction of genomics, A.I. studs have altered many bull-handling and semen collection processes to better accommodate the smaller-sized sires.

PHOTO 2: 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. Photos courtesy of Genex.

Ben Rogers
  • Ben Rogers

  • Operations Coordinator
  • Genex
  • Email Ben Rogers