08 Aug 2019
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Genomics: What you need to know

Genomic testing is available for Holsteins, Jerseys, Ayrshires and Guernseys through our Approved Registered Cattle Scheme which offers competitive rates for tissue tags. By taking a DNA sample from a calf, it is possible to get an immediate indication of genetic merit, rather than having to wait for that animal to calve and start milking/breeding. Darren Todd, of NBDC, answers the how’s and whys of genomic testing heifers.

Frequently asked questions about genomic testing
By Dr Darren Todd, Holstein UK Geneticist

1. Why do a genomic test?

Genomic testing gives twice as much genetic information on a young animal as pedigree index or parent average.  

Use genomic testing to identify the best heifers to;

1) retain as replacements

2) mate to sexed semen

3) flush as embryo dams

For males, identify potential AI candidate bulls and give more information on potential stock bulls.

2. What animals should be tested?

Heifers and young bulls are most suitable for genomic testing. These are the animals in the herd with the least known about their genetic merit but also with the highest potential type merit and PLI values.

3. What tests are available? 

Holstein UK offers high density (HD) tests for both males and females.

3. How do I collect a DNA sample?

Either by sending in a tissue tag vial or by requesting a hair sample kit from Holstein UK and taking a hair sample with roots from the tail switch, attaching it to the hair card supplied and returning the sample by post.

4. How long does the process take?

6 to 8 weeks depending on what date you return the sample (for accurate dates please see lab dates schedule document on the HUK website).

5. What information do I get back on my animals?

Each animal receives a full set of UK genomic type, production and health trait results including the GPLI index.

6. How do I access the results?

Individual female and official male results are published on Holstein UK web factsheet. Female group results, unofficial males and GTPI can be viewed through the member's section on the HUK website under 'genomic testing’.

7. Is a UK test the same as a US or Canadian test?

No, a UK test (GPLI) is the only one which will give you genetic merit in UK conditions.

US (GTPI) and Canadian (GLPI) results will give information on performance in those countries and are not relevant in UK conditions. Use of these tests should only be considered for international marketing purposes.

8. Are recessives and haplotypes included in the test?

Yes, a number of genetic tests are included in the price of the genomic test: Haplotypes, Dumps, Blad, Citrullinemia, Beta Lactoglobulin, Kappa Casein, Beta Cassein A/B and Leptin.

For an additional charge, the member can also request the following tests: Coat Colour, Polled status, Beta Casein A2, Brachyspina, HCD and CVM. If these tests are requested at the same time as the genomic test, then they are offered at a slightly reduced price.

9. What is the difference between the unofficial and official male test?

Any male under 15 months of age can obtain an unofficial UK genomic result. This is only available to the owner and can be used to sell the bull but is not publishable for semen marketing purposes.

If it is intended that the bull will be marketed through AI, then the result must be made official by payment of the extra fee of £250 to AHDB dairy.

10. What is the difference between a genotype and a genomic test?

The DNA code is read to produce a GENOTYPE.

The genetic merit of this genotype is measured using a GENOMIC test.

(Be aware that the term genotype is also used in parentage testing)

11. Is a genomic test enough to prove parentage?

Only if both the sire and dam also have a UK genomic evaluation.

12. Does a genomic parentage test calf receive a UK genomic evaluation for use in breeding decisions?

Yes as long as the parentage check is successful.

13. How do I know if a calf is eligible for a genomic parentage check?

When registering the calf, Holstein UK registration software will identify eligible calves for the user.

14. How do I know if the sire and/or dam have a UK genomic evaluation?

A. You can check this using the animal search on Holstein UK website.

15. Can imported embryos undergo a genomic parentage test?

A. Yes if both sire and dam have a UK genomic evaluation.

16. I didn't get results back? What percentage of tests don't produce a result?

A small number (<5%) of genomic tests do not yield a result. These animals can be resampled. To avoid this, it is important to take a good DNA sample and make sure each sample is properly identified and matches the calf tested correctly.

17. Can a foreign genomic test be used to produce a UK test result?

Yes, but only if the genotype file is available.

If you import an animal which has been genomic tested abroad and wish to get UK results, make sure you contact the vendor to arrange for the genotype file information to be sent to AHDB Dairy.

18. How can I request a genomic test?

Genomic tests can be requested during the registration process: either on the telephone or internet via WebReg. They can also be requested via the Member’s section of the Holstein UK website or by telephoning Membership Services on 01923 695200.

For further advice on which test to use please contact Darren Todd on 01923 695 275 or email darrentodd@holstein-uk.org