Genomic testing has been used by AI companies for years to accelerate the genetic progress of bulls. But it is now being used for females. The benefits of genomic testing in a dairy herd are being increasingly explored in the industry. We asked Mike Christie, “Mr Genetics”, some questions:

In short, what is genomic testing?

Genomic testing is simply the process of identifying the genetic potential of an animal and their offspring. It is well established in helping identify the traits of sires for selection, and it is now increasingly being used in commercial dairy herds on heifers.

Obviously, like humans, each animal has a unique set of genes. Depending on your chosen breeding traits and strategy; some animals will be better suited to increasing your herd genetic merit more quickly than others.

How can it benefit a herd?

With the genomic testing results, you can identify the top animals to breed from based on your desired traits.

Rearing a heifer replacement isn’t cheap; I think the figure is currently around an average of £1800. So genomic testing also gives the opportunity for you to become a bit more ruthless with your breeding strategy. Identify those top heifers, 1st and 2nd lactation cows for replacements and utilise the lower ranked animals for beef or sale if they don’t align with your strategy. Furthermore, sexed semen can be targeted more efficiently. This gives an immediate saving on sexed semen costs and breeding more lower ranking heifers to beef. This can help towards cash flow whilst boosting genetics in the herd.

Can any dairy herd carry out genomic testing?

If milk recording, all herds should have access to the AHDB Herd Genetic Report. However, as suggested you have to wait until after first calving to establish her genetic merit.

With alternative genomic testing, such as Clarifide which has come over from the US, samples are taken from young stock and checked against a number of index’s. Currently, you must be one of six breeds; Holstein, British Friesian, Guernsey, Brown Swiss, Jersey and Ayrshire and at approximately 87.5% purebred in order to get reliable results.

What age can heifers be tested from?

The benefit of Clarifide and other tests from semen companies is that testing can be done as early as needed. We would probably recommend it’s carried out well before serving so that you can utilise the results for maximum effect. But many do carry it out after weaning, to avoid any loss.

What figures do you get back and are they reliable?

The results are 60-65% accurate. This is pretty good compared to simply using parent averages which is around 25%.

The actual figures reported on include:

  • Production – milk, fat and protein
  • Fertility
  • Lifespan, maintenance, temperament, ease of milk
  • TB Advantage
  • Locomotion and Condition Score
  • Milk Protein Components
  • Genetic recessives (e.g. haplotypes)
  • Verifying correct parentage (up to 10% of parentage is incorrect)
  • PLI
Genomic Testing

Why are vets being involved in breeding strategy?

Genetics and breeding strategy is a large aspect of herd health. Genomics is a very scientific area in which many vets can help advise on, especially in relation to breeding outcomes that might affect herd performance. That said, everything works better when used in a team approach on farm and breeding advisors, if you have one, play a huge part in this.

Hopefully this gave you a very brief overview of genomic testing. It’s quite a meaty subject so if you have more questions about genomic testing, please let us know. Our Clarifide trained vets are Mike, Rob Hall and Roland.