Key questions on genomic testing

Here is a sample – with my replies.

Q. Why do a genomic test? A. 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 retain as replacements, mate to sexed semen, and flush as embryo dams. For males, identify potential AI candidate bulls and give more information on potential stock bulls.

Q. What animals should be tested? A. 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.

Q. What tests are available? A. Holstein UK offers high density tests for both males and females.

Q. How do I collect a DNA sample? A. 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.

Q. How long does the process take? A. Six to eight weeks depending on what date you return the sample.

Q. What information do I get back on my animals? A. Each animal receives a full set of UK genomic type, production and health trait results including the GPLI index.

Q. How do I access the results? A. 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 members section on the HUK website under 'genomic testing’.

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

Q. Are recessives and haplotypes included in the test? A. Yes, a number of genetic tests are included in the price of the genomic test.

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

Dr Darren Todd, Holstein UK geneticist