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New in April 2019: Crossbred evaluations

The Council on Dairy Cattle Breeding (CDCB) will now release genomic evaluations for crossbred animals. In recent years, increased crossbreeding, paired with increased adoption of genomic testing in commercial environments, has led to the demand – and accessibility – to calculate genomic evaluations on crossbred animals.

What does this mean for you?

You can expect genetic value estimates for crossbred animals to be slightly less accurate than purebred estimates. CDCB will calculate crossbred genomic predictions as a weighted average of the respective single breed evaluations. This means that you’ll see improved accuracy for some crossbred animals already receiving evaluations. For example, animals that are about 85% Jersey and 15% Holstein, will have greater accuracy, because instead of being evaluated as only a Jersey, their Holstein proportion will now more accurately be accounted for within that animal’s evaluation.

Another result of this update is a slightly increased accuracy of purebred evaluations. This is because crossbred animals with a BBR of <=94% will not be included in individual breed evaluations.

The details

There are five main breeds of dairy cattle with genomic evaluations in the US: Holstein, Jersey, Brown Swiss, Ayrshire, and Guernsey.

Currently, BBR, which stands for Breed Base Representation, is an estimate of the percent of DNA contributed to that animal by each of these five breeds. Going forward, animals will be divided as follows:

  • BBR >= 94% will be defined as a purebred.
  • BBR >= 90% will still be evaluated with the breed of its highest BBR.
  • BBR < 90% will be evaluated in a blended group, and their predictions will be based on a weighted combination of marker effects from the different comprising breeds.

If an animal has a BBR < 90%, CDCB will most often label that animal as the breed of its highest BBR. The exception to this is first generation crossbreds with a BBR of the highest breed less than 55%.

Some traits are only evaluated within certain breeds or are difficult to compare across breeds. Because of that, crossbred animals will have type traits, calving traits (Holstein and Brown Swiss only), and health traits (Holstein only) from one breed only – they will not be blended.

There will also be no haplotypes released for the crossbred animals at the April 2019 release.

Keep this in mind…

If you implement crossbreeding as part of your genetic strategy, these new crossbred evaluations are big news. This update will provide you with more accurate information to make better decisions, regardless of your herd’s breed composition.

Want to learn more?

Check out the webinar addressing the new crossbred evaluations from CDCB.

 

Published in partnership with Ashley Mikshowsky and Doug Bjelland, PEAK Geneticists

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Haplotype & genomic reliability updates

Based on new findings from the Council on Dairy Cattle Breeding (CDCB), one new haplotype will be added, and two others removed, starting with December 2018 proofs. Alta Bull Search and Alta GPS will be programmed according to this new information.

A new Holstein haplotype, HH6, was recently identified in France, and is currently found in about 0.5% of animals in the US Holstein population. Mating two HH6 carriers is expected to yield a 7%-11% drop in conception rate.

Further research into the JH2 haplotype in Jerseys and the BH1 haplotype in Brown Swiss showed no significant fertility losses on matings between carriers. This, paired with the fact that researchers could find no causative mutation on these two haplotypes, means they will no longer be reported.

Gene test advancements

In addition to new and discontinued haplotypes, the reported haplotypes are also gaining accuracy. PEAK Geneticist, Doug Bjelland, compares the improved accuracy of haplotypes to locating a house on a map. The previous way of recognizing haplotypes essentially showed us which street a house is located on. Now, because of gene test advancements for causative mutations to determine haplotypes, we know exactly where on that street a house is located.

Upgraded genomic reliability

Improved genomic accuracy also extends beyond the gene test. Researchers are now using an 80k SNP chip. This means they are using nearly 80,000 markers on the genome, up from the previous 60,000 used since 2014.

The additional markers, combined with a new reference genome, give genomic predictions about a 1% – 2% improvement in reliability.

What does this mean for you?

We want to keep you up-to-date on the newest genetic findings. Updates on haplotypes and genomic accuracy are one part of that. Because the haplotype updates will be accounted for within the AltaGPS program, you can have confidence that potential carriers of two bulls will not be mated together. That means your clients are protected from any potential fertility losses that could result in mating two carriers of any given haplotype.

Improved genomic accuracy should give you, and your clients, even more confidence that genomics and genetics continue to advance at more rapid rate. It’s as important now as it ever has been, to ensure your clients select genetics according to their customized genetic plan so the progress they make aligns with their current situation and future goals.

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