Genetic Insights: Enhancing Dairy Herds through DNA Testing

The ability to perform DNA testing on dairy cattle is one of the most impactful technological advancements of the century. The resulting ability to make selection decisions based on genomic data has accelerated the industry's capability to make progress. Since the first genomic evaluations became available in 2009, there has been an acceleration in year-over-year genetic progress.

The above graph from the Council on Dairy Cattle Breeding shows how much faster we have created higher Net Merit Holsteins in both the male and female populations since 2009. The primary reason is that artificial insemination companies utilizing genomic data can bring genetically superior bulls to the market at a younger age. Dairy producers then use these bulls to create better females for their operations. That is why we see accelerated progress in both male and female Holstein populations.

If we look closely at the graph, we see that gap between the average Net Merit for males and females is growing larger each year. The data suggests that quality of the male population used for artificial insemination is accelerating more quickly than that of the female population. This is expected as the male population is subject to more intense selection, augmented by genomic data.

Dairy producers who utilize artificial insemination reap the benefit of genomic testing by using these high-quality sires in their breeding programs. However, it doesn't have to stop there. With commercial genomic testing for dairy females, producers can now build a breeding program where they select both high-quality sires and high-quality dams. This type of breeding program creates replacements best suited for their business goals.

Leveraging genomic data to select females for replacement creation does not have to be overwhelming. DNA testing is not supposed to be a standalone strategy, but the data yielded from testing should be incorporated into a dairy producer's breeding and selection strategy.

The first step is to create a plan based on how many heifer replacements are produced each month versus how many are needed. The number of heifer replacements needed each month is controlled by the number of animals that are culled from the herd. This data includes mature cows being culled or lost due to death and the number of heifers that leave the herd before maturity. Goals for growth should also be factored into replacement needs.

The second step is determining what genomic information to focus on for selection. When making selection decisions, it helps to use an index like Net Merit or a custom index based on traits important to your business.

Once the number of replacements needed is known and the criteria set, the results from genomic testing will determine which replacements are the best to keep from the total number produced.

The most important aspect of this system is keeping it a routine part of the business strategy. The correct number of replacements of the highest genetic quality get retained each month. The genomic data from those kept can determine the best breeding strategy for when they reach breeding age.

Targeting the use of sexed semen based on the genomic data and inventory needs will continue to drive progress while limiting the number of excess replacements created. Females not targeted for sexed semen usage can then be bred to beef semen, creating value-added calves and additional revenue from sales.

DNA testing is no longer just a tool for artificial insemination companies. It is an effective means for dairy producers to place selection emphasis within the females of their herd. Those choosing to test will accelerate their genetic progress, save the associated cost of raising excess replacements, and be able to develop alternative revenue sources by breeding lower-quality animals to beef semen.

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