Breeding Matters - Genomics vs Proven Pedigrees?
Date Posted: 17th February 2026
Debbie McConnell, Principal Group Scientist, AI Services
In 2009, genomics burst onto the scene with the first full sequencing of the bovine genome. A Hereford cow from a cattle ranch in eastern Montana was the first animal to have her complete DNA sequence decoded. It was a mammoth project that took six years, bringing together 300 scientists and identifying 2.5 billion individual parts to the DNA sequence.
Since then, there has been rapid progress in the application of genomics to livestock farming. This has resulted in significant advantages by increasing both the range of traits we can now choose to breed for (e.g. feed efficiency, environmental footprint, disease resistance), and by the speed at which we can make genetic progress. In 2025, the average age of the parents of Holstein sires available in the US was 30 months old; in 1990 the same figure was seven years.
However, despite the potential gains to be made from using genomic information, many people still ask which is better when it comes to choosing AI sires: selecting bulls on genomic proofs or choosing animals with proven pedigrees which have physical performance data included in their calculation.
Because genomic proofs are based solely on the DNA they are more likely to change as more data is incorporated into their genetic evaluations. And, with new data being added from across the globe multiple times a year, there is plenty of scope for the numbers to change. To mitigate this risk, looking at the reliability figures published alongside the genomic proof will give you an idea of how likely the data is to change. Typical reliabilities can range from 20 – 99%, with higher values being more reliable.
In contrast, genetic proofs for proven sires will change significantly less when new information is added into the evaluation, giving more confidence in the predicted performance of any offspring from that sire. However, because it takes around two years to have semen available from a genomic sire compared to five years before data can be generated for a proven sire, the reality is that by the time proven information becomes available, the corresponding genomic bulls have progressed, and more advanced genetics are available.
Ultimately, the decision to use genomics or proven is individual to each farm and involves a trade-off between potential gain (genomics) and security (proven bulls). However, with the global impact genomics is having on our breeding programmes, can we really afford to miss out on the potential it offers?