Genomic Testing – Building a Better Future for Guernsey Cattle
Genomic testing is rapidly becoming an essential tool for dairy breeders, providing a clearer picture of an animal’s genetic potential from an early age. For Guernsey breeders, it offers the opportunity to make more informed breeding decisions, accelerate genetic gain and strengthen the future of the breed.
Using a simple DNA sample, genomic testing analyses thousands of genetic markers across an animal’s genome to provide a more accurate estimate of its breeding value than pedigree alone. According to AHDB, the reliability of a young heifer’s genetic evaluation increases from around **30% based on parent average** to almost **60% when genomic information is included**, allowing breeders to make confident decisions long before a cow has any production records.
Better decisions, earlier
Every calf inherits a unique combination of genes from its parents, meaning even full sisters can have very different genetic potential. Genomic testing identifies these differences, enabling breeders to:
* Select the very best replacement heifers.
* Identify future bull mothers with greater confidence.
* Make better use of sexed and beef semen.
* Verify parentage and improve pedigree accuracy.
* Screen for recognised inherited genetic conditions.
Rather than waiting two or three years for milk recording data, breeders can make informed breeding decisions within weeks of a calf being born.
What does the evidence show?
AHDB has analysed genomic testing across UK dairy breeds, including Holstein, Friesian, Jersey, Ayrshire and Guernsey. As Holsteins make up the majority of the national dairy herd, the headline figures are largely influenced by Holstein data, but they demonstrate the value of genomic testing across the dairy industry.
In 2024, more than **112,500 dairy females** were genomically tested in the UK, a **19% increase** on the previous year, showing the rapid adoption of the technology by dairy farmers.
AHDB also found that herds testing **75–100% of their heifer calves** had an average **Profitable Lifetime Index (£PLI) of £430**, compared with **£237** in herds testing fewer than 25% of heifers. That represents a **£193 genetic advantage per animal**.
For a typical 175-cow dairy herd, AHDB estimates this difference equates to approximately **£19,300 in theoretical genetic value**, while analysis of commercial herd performance suggests the overall financial benefit could exceed **£50,000**.
These figures should not be interpreted as the direct result of genomic testing alone. Rather, they reflect the cumulative benefit of making consistently better breeding decisions over several generations using genomic information.
Why this matters for Guernsey breeders
Although the national figures are heavily influenced by Holstein herds, the same principles apply to Guernsey cattle. Genomic testing enables Guernsey breeders to identify the animals with the greatest genetic potential for milk production, fertility, longevity, health and efficiency, helping accelerate genetic improvement while preserving the unique characteristics of the breed.
There is an additional benefit for Guernsey breeders. As a smaller breed, every animal that is genomically tested contributes valuable information to the breed’s genomic reference population. AHDB works with international partners to combine Guernsey genomic data from the UK, Canada, the USA and Italy, improving the accuracy of genomic evaluations for future generations.
Investing in the future
Genetic improvement is permanent and cumulative. Every breeding decision influences the next generation, and every genomically tested animal strengthens the information available to breeders.
For Guernsey breeders, genomic testing is more than simply receiving a DNA report. It is an investment in more informed breeding decisions, healthier and more productive cattle, and the continued improvement of one of the world’s most efficient and distinctive dairy breeds.
Currently the EGCS uses Cogent for genomic tests through the society.
Cogent testing included traits and evaluations:
* Full Official UK Evaluation
* Full EcoFeed Suite of Traits
* Full RoboticCow Evaluation
* Milk Protein variants: Kappa Casein, Beta Casein, Beta Lactoglobulin
* Polled status
* Genetic abnormalities and haplotypes, including HCD, HH1–HH6, Muscle Weakness, Hair Colour, and more
More can be read
https://cogentuk.com/precision/dna/dna-pro
For more information on the benefits of genomic testing, take a look at these articles:
https://ahdb.org.uk/news/genomic-testing-reaches-new-heights
https://breedingdairy.ahdb.org.uk/learn/genomics/
https://www.nmr.co.uk/genomic-testing
For more information please contact one of the Future of the Breed committee who are always happy to have a chat about genomic testing and the benefits. Speak to the office who will link you up with a member.
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