click image to zoom Which one of these three-month-old heifer calves will be the better cow? The half-siblings share the same sire, were born within a week of each other, the dam of each is a first-lactation animal and they receive identical care, nutrition and housing. Neither has had scours, respiratory disease or any other serious health challenge to date.
At first glance, No. 7897 holds the show-ring edge over No. 7898, at least for now. But will she be more profitable?
That’s where genomic testing comes into play. It’s impossible to know which is the better heifer just by looking at them. Health data are helpful, but peering into an animal’s genetic makeup can significantly improve your ability to predict which heifer will become the more valuable cow.
Here’s why you should consider what this technology can do for your herd.
Much of the dairy industry’s amazing productivity has come through sire impacts and their ability to pass genes to offspring. Less information is available on cow contributions since, unlike AI sires, a cow has fewer production records and much fewer offspring.
The development of DNA marker testing technology (see sidebar on page 19) opens up opportunities within the female bovine population for faster genetic progress. In other words, if you genomically test cows and heifers, you should be able to develop a genetically superior, more profitable herd than you would by only using sire data.
One caveat. You must have a plan for how to use the information, notes Chris Roeder, Pfizer Animal Health area sales manager who works with genomic testing. Otherwise, you simply have additional records taking up space on your computer or desk — data that you paid to obtain, but sits unused.
You must also note that this technology is a long-term investment that pays you back over a number of years. If you’re looking for a quick fix, you’re looking in the wrong place.
With that in mind, female genomic data offer you a new replacement evaluation tool with early-intervention possibilities.
In herds that have used sexed semen and now have extra replacement heifers, genomic-testing can be cost-effective for sorting out the “duds” and culling them from the herd before investing too much time, feed and money in them, says Kent Weigel, University of Wisconsin dairy genetics professor and chair of the Department of Dairy Science. (See “Weed out unworthy heifers” at: http://tinyurl.com/3kfcl47 )
For example, let’s say you test three heifers with similar pedigrees to see what kind of returns you can expect on your investment. Using genomic results for Net Merit index (just one of many measures available) of -124, 125 and 48, respectively, you can expect that the second heifer, over her lifetime, would generate an additional $498 return ($125 - (-$124) = 249 x 2) over the first heifer, which is expected to be significantly less profitable.
Given current economic realities and heifer-rearing expenses that can range from $1,600 to more than $2,000, depending on your situation, results like these can help you determine early on which heifers you want to raise and which should probably leave your herd. You’ll be more efficient with increasingly expensive feed resources and save on other rearing costs.
Farmers are looking at managing heifer inventories differently and more intensively than in the past, says Chuck Sattler, vice president of genetic programs for Select Sires. “This technology offers a way to do that.”
Of course, you can predict a calf’s genetic potential by using sire and dam Predicted Transmitting Ability data and skip the cost of genomic testing. But results are not especially accurate (about 30 percent). And if you don’t know this information, due to either missing or incomplete records or animal misidentification, you’re back to square one.
Furthermore, genomic testing offers prediction accuracy that approaches 70 percent.
It’s also a means to establish the production potential for purchased cattle that arrive with little or no pedigree data.
Selective breeding and payoff
In addition, test results offer a new way to manage your female population.
Besides providing information on which animals to cull, farmers are using this technology to decide with heifers to breed with sexed semen or which animals are candidates for embryo transfer, says Roeder.
“The obvious application is for selection,” agrees Sattler, “So, if you plan to breed animals differently, this technology makes a lot of sense.”
Of course, all of this only matters if the technology pays for itself. Be sure to run the numbers for your individual situation. Computer models suggest return on investment results are highly herd-specific.
So far, operational size doesn’t seem to be a significant economic factor. “I think the technology is scale-neutral, because it’s really the percentage of animals to test, or the percentage of animals available to be culled, that matters,” Weigel notes.
Big picture, small SNP
Genomic testing moved into high gear with the sequencing of the bovine genome and development a few years ago of a test that could genotype bovine DNA markers known as single nucleotide polymorphisms (SNPs). This opened up a new world of faster genetic testing with up to double the accuracy of traditional parent averages. It enabled users to better differentiate between siblings, sped up genetic improvement and improved the reliability of progeny testing results for economically relevant and even low-heritability traits, including health and fitness traits.
Initial tests focused on 50,000 SNPs and at roughly $250 per test, were used primarily for genomic testing young sires by bovine genetics organizations or for testing elite females.
Within the last year, a test has been developed that examines about 3,000 SNPs, and the cost dropped to less than $50 per test. This 3K test, as it is known, is available through a variety of vendors, including bovine genetics organizations, breed associations and pharmaceutical companies, as well as private labs. Additional genomic tests are in development, but still in the testing stage.
Nature PLUS nurture
Calves that don’t get an adequate supply of IgG and other factors in colostrum at birth often go on to be less-profitable members of the herd. This is also dependent on nutrient intake prior to weaning -- the higher the total nutrient intake, both energy and protein, the greater the milk-producing ability, says Kent Weigel, University of Wisconsin dairy genetics professor and chair of the Department of Dairy Science . “We always think about nature vs. nurture, but in this case what we really need to do is talk about nature plus nurture. By that, I mean that we should combine the results of genomic testing with the health history of the calf when making replacement decisions,” he says. “This is something we’ll be working on over the summer.”