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Monthly Archives: April 2019

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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New trait from CDCB: Early First Calving

As part of April 2019 the Council on Dairy Cattle Breeding (CDCB) is releasing a newly evaluated trait: Early First Calving (EFC).

Because genetics and management both play a role in heifer development, having the ability to select for animals that calve in earlier can help increase your herd’s profitability.

Heifer rearing accounts for 15-20% of the total cost of milk production. This includes feed, housing, labor, and health care costs. Raising a heifer can cost an estimated $2.50 a day to raise a heifer. So decreasing the age at first calving can add up to substantial savings. Another factor to consider is how the age at first calving affects the heifer’s income after she joins the milking herd.

Early First Calving will be expressed as age in days at first calving.

Animals expected to transmit genetics that decrease the age at first calving will have a positive EFC value, because calving younger is seen as more beneficial. Animals transmitting genetics that increase the age at first calving will have a negative EFC value, because calving at an older age is less beneficial.

If you’re looking to select for EFC as part of your genetic plan, here’s what you’ll see. A bull with a PTA of +2 days for EFC has genetics estimated to reduce his daughter’s age at first calving by two days compared to a bull with a PTA of 0 for EFC. The heritability of EFC is low, at 2.3%. The average reliability for young genotyped Holsteins is about 66% and for Jereys, it’s about 51%.

As with the release of any new trait, it’s important to keep your herd’s current situation and future goals in mind. Ask yourself how you’re paid for milk, why cows leave your herd, and what type of cows fit your environment in order to emphasize only the traits that will most affect your farm’s bottom line.

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