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Should you get your females genomic tested?

Nate Zwald Published on 23 December 2010

With the enormous buzz about genomics, many questions surface about how a commercial dairyman should use this technology: How will genomics affect the industry? Should I use some, all or no genomic bulls?

However, now that a far more economical ($35-$45) genomic test is available to the industry, the question often asked is “Should I test my females?” Of course this question inspires a rather extensive list of other questions, so what awaits readers is a list of those most frequently asked over the past few months:



Q. Should I genomic test my females with the 3K chip?
To properly answer this question, you must first ask yourself what you are going to do with the results. If you are going to use the results to manage, sort or breed your animals differently, then you should consider testing if that information will help you make a better decision.

If you can’t see how it makes a better economic decision that creates more bottom-line profit for your dairy today or in the future, then the investment is not worth it.

Although the cost of the genomic test is now much more economical, it is still a substantial investment when multiplied over many animals.

Investments have to pay off, and not only should the cost of the investment be considered, but also the opportunity cost and potential return of investing those resources in other places.

Q. Genomic testing has been around for a while. What makes this new test more economical?
A new chip with about 3,000 SNPs is now available. Previously the only chip available had about 50,000 SNPs.


The new 3K chip is simply a subset of the most important SNPs from the 50K chip, making it less costly, while still providing a substantial level of accuracy.

Q. Who is offering genomic testing for females?
Many organizations are currently providing genomic testing for females, including A.I. companies, pharmaceutical companies, breed associations and even private labs.

Others are also likely to begin providing this service. All information (genotypes) is sent to the USDA as the central organization responsible for calculation of genetic predictions.

Q. How can I evaluate if genomic testing my females is correct for me?
Genomic testing your females offers the opportunity to more accurately predict and rank animals within your herd on their genetic potential.

Ranking your herd can have some real advantages when it comes to a number of management decisions: if you want to use sexed semen on the top portion of your herd, if you want to cull the bottom end of your herd and if you want to do embryo transfer work on extreme genetic outliers within the herd.

Q. What is the accuracy gain between unknown animals, parent average, 3K, 50K? How does this new technology compare to that currently used for A.I. bulls?
We assume each unknown animal is “average” with basically 0 percent reliability. With parent average, we can assume about 42 percent reliability, and with a 3K test we generally get about 60 percent reliability for an index like Net Merit, TPI or one you create for your own dairy. The 50K test (which is currently used for all A.I. bulls) has a reliability of about 72 percent for indexes.


Q. What does that accuracy gain mean for genetic progress in my herd?
Most farms breed every available animal for a replacement. If this is your practice, and you plan to continue this practice, then genomic testing will have no value for your dairy.

If you plan to use the results to focus on generating replacements from the upper end of your herd, then genomic testing can have a positive impact in some situations – especially if you have missing or inaccurate parent identification.

Q. What will the genomic results look like if I do decide to test my animals?
The results will look just like a bull “proof.” Animals will get predictions for traits like PTAM, PTAF, PTAP, PL, DPR, SCS, PTAT, UDC, FLC and all linear-type traits.

If you test a group of animals, you can import your results into your herd management program or a spreadsheet and sort them on an index such as TPI or Net Merit, similar to bull evaluations.

Q. Can I rank my animals on their genetic potential without genomic testing them?
Yes. Although it is not often considered, a commercial dairy that has complete and accurate identification can create a ranking on genetic potential based on parent average, with a considerable amount of reliability (about 40 percent).

In fact, a parent average can be constructed for each trait in a bull’s “proof” and will look very similar to genomic results with a lower level of accuracy.

This is very important because for a herd with complete and accurate identification of sires and maternal grandsires, the choice to genome test heifers or not is a decision about the accuracy of the ranking based on parent average vs. the accuracy of the ranking with genomics.

Expected changes in NM from Parent Average after genomic testing
Q. What is a parent average?

Parent average is the average genetics of the sire and dam of the animal. Oftentimes a parent average is estimated with the Sire and Maternal Grandsire (MGS) of the animal when performance data of the dam does not exist.

Q. I record Sire x MGS; is my parent average accurate?
That depends on the accuracy of your identification. If you do a good job recording breedings and identifying calves, making both the sire and MGS accurate, then a parent average will have enough accuracy to begin ranking your animals for some basic purposes.

Q. Who can do the work on parent average/index ranking?
You should work with a trusted genetic adviser – often your A.I. company. It is very important to remember that before ranking your animals, you first have to determine what you are ranking them for.

This means that you first need to have a developed genetic plan so you focus on the traits important to you. For example, some dairies will value just fluid milk production, some will value cheese, others might value health traits or conformation. Ideally, each dairy should decide what is economically important to them.

Q. What if I do not have accurate or complete identification in my herd?
Without complete and accurate ID, the ranking of heifers based on parent average alone becomes much more difficult, and oftentimes an impossible task.

Often, the accuracy of ID within individual herds is overestimated, and the real miss-ID rate in the industry is greater than 25 percent. If you question your ID accuracy, genomic testing provides an opportunity to determine the accuracy of your identification, in addition to accurately ranking your animals.

Q. If I have accurate and complete identification in my herd, in what situations does it make sense for me to genome test my females?
The answer will again depend on what you are going to do with the information. If you are simply going to use it to see how you rank genetically among other farms, it clearly will not pay off.

If you are going to use it to cull the bottom animals in your herd, it is unlikely to pay off, as they can be selected based solely on parent average. If you are going to use the results for selection of which animals should get sexed semen, it is also unlikely to pay off.

However, if you want to select the most extreme animals to do embryo transfer work on, it is likely a good strategy to first genome test a preselected group to ensure only the very best are flushed.

Q. Why won’t using this technology to select my bottom animals for culling and my top animals for sexed semen pay off?
In some extreme situations it may, but if your herd performs as expected, and you have complete and accurate ID, then your virgin heifers will have a parent average reliability of around 40 percent for Net Merit or TPI. That reliability will increase to about 60 percent reliability with the genomic test.

Using statistics, we can assume the probability of an animal increasing by more than 100 NM or 150 TPI points is only about 11 percent, and likewise, an animal decreasing by those amounts is only about 11 percent.

Using a more extreme example, the probability of an individual animal changing by at least 200 NM or 300 TPI points is only 1 percent.

Q. If 11 percent of my animals will go up by 100 NM or 150 TPI and another 11 percent will go down by the same amount, won’t that make a considerable difference in the ranking of my animals?
It will make a substantial difference in the ranking of a few individual animals, but most farms are dealing with groups of animals. For example, the genetically highest group could be destined for insemination with sexed semen, while the poorest group in terms of genetics would be destined to be culled.

When dealing with groups, we need to consider how much the average of the group would change if we genomic test the heifers versus if we used only a parent average to rank them.

If your herd is normal, about 95 percent of animals will be between +/-400 NM and the average of your virgin heifers might be 100 NM. If you wanted to select the top 25 percent for sexed semen usage, the group of heifers selected for sexed semen would likely be those heifers greater than 250NM.

The bottom 10 percent (which would be culled) would be less than -150NM. In this situation, what is the probability that a heifer selected for sexed semen based on parent average (top 25 percent) would fall into the group to be culled (bottom 10 percent) after genome testing?

Referring back to the last answer, there is only a 1 percent chance that an animal will change by 200NM points, so the likelihood of an animal going from a sexed semen candidate to a cull (or vice versa) is nearly zero, as she would have to change by at least 400NM.

Q. But an animal could still change significantly and therefore the group to cull or use sexed semen on would be a different group?
This is absolutely true, but we need to ask what the effect of this change is. With a normal herd, there is less than a 1 percent chance that an animal in your top half, based on parent average, will end up in your bottom 10 percent after genome testing.

Therefore, the animals crossing the threshold and changing the group to be culled (or be selected for sexed semen usage) do not change the average of the group significantly.

Figure 1
Q. What is “risk” or “error” in the 3K evaluation?

There is not a lot of “risk” in the 3K evaluation. It will always give you more reliable information than simply using parent average (or no information).

The real risk is the opportunity cost of investing thousands of dollars when those dollars could have better returns if invested in other ways. Generally, using those dollars to simply buy better genetics by way of semen should be considered as an alternative investment.

(**Figure 1 represents a herd situation where the top 25 percent of animals based on parent average would be selected for sexed semen, and the bottom 10 percent would be sold. In a normal situation, there is almost zero opportunity for animals selected for culling based on parent average to ultimately end up in the sexed semen category after genomic testing.)

Q. If I’m expanding or need to buy replacements, should I only buy heifers with 3K?
This is an interesting question, and in some situations it may make sense to pay for testing of unknown heifers. In a normal situation, you will need to test at least twice the number of heifers you plan to buy to make this a financially sound decision.

This decision will be determined by the ratio of replacement cost vs. beef price. At the current historically low cost of replacements, genome testing these unknown animals is not likely to be an investment that would pay off; however, if we one day experience extremely high prices for replacements and low prices for beef, as has been the case in the past, it would make sense.

Q. If I choose to genomic test unknown animals, what will the benefits be?
“Sire discovery,” which means we will be able to determine who the sire of the tested animal is – provided it was an A.I. sire. “Sire discovery” is the first step in determining accurate genomic predictions.

Ultimately you will receive a genomic “proof” just like other animals, or a bull “proof,” as described earlier.

Q. Can I stop milk recording and classification with a 3K test?
Generally, milk recording is done for management, not genetic reasons. We must remember that although the genomic test gives us a lot of valuable information on the genetics of an animal, genetic potential does not answer management questions.

For example, an animal with a high cell count on test day still may need to be treated or culled, and genomic information will certainly not give us that information.

It is also important that we continue to gather phenotypic data (through milk recording and classification) so our genomic predictions continue to be current, relevant and accurate for an ever-changing dairy economy.

Q. What is the bottom line?
Genomic testing is an excellent technology and is certainly exciting. However, exercise caution when deciding if this is the right investment for you.

As with any new information or tool, remember to ask yourself how you will use that information and how the investment will pay off. If you can answer those questions and it is a profitable decision for your dairy, then it is right for you. If those questions only inspire more questions, proceed with caution.  PD

References omitted due to space but are available upon request to .

Nate Zwald