The TBA hosted a successful and well-attended seminar entitled ‘Nature or Nurture’ in July, with informative speakers on several subjects including genetic diversity – an increasing challenge to  the thoroughbred herd. It is a fact that with any closed breeding community, genetic compromise becomes an issue as either the population decreases and/or there is an overuse or reliance upon certain sires or sire lines.

The thoroughbred (in Britain and beyond) now fits neatly within all parts of that sentence, as a small number of sire lines have held considerable influence over the past 20 years. At the same time,  the available gene pool has continued to contract simply due to mare numbers dwindling, while the availability of stallions has declined from more than 300 to just 107 over the past two  decades in Britain. Fashion trends, commercial forces and shuttling between the northern and southern hemispheres have delivered increasing book sizes and progeny numbers for the popular stallions, yet others find mares more difficult to come by.

As the foal crop continues to fall, the availability of stallions will also decline and so the British breeding industry increases the risk and exposure to a genetic imbalance that if not acted upon will see the potential of us eventually facing the same issues and crises many other breeds have experienced, with the Cleveland Bay being a good example.

This breed, once near extinction, is now achieving a slow but steady genetic recovery thanks to dedicated breed management efforts. This recovery involves using a population management tool  called SPARKS to analyse pedigrees (mean kinship) and minimise inbreeding.

SPARKS helps breeders make informed decisions about matings to maintain genetic diversity, essentially a ‘family tree’ for the breed. This tool analyses pedigrees, sometimes going back 30  generations, to identify potential inbreeding issues and suggests pairings that will help improve genetic diversity. The aim is to mate individuals with similar levels of inbreeding and to preserve the rarer genetic material. Consequently, breeders can access estimated inbreeding coefficients for the potential progeny outcomes of mares they own or manage, when assessed against the entire stallion population.

This is a thoroughly responsible and engaged response to an issue that, not followed, could have taken the Cleveland Bay the way of the dodo!

For some years, the TBA has been aware of the prospects of the thoroughbred facing similar challenges, with published research also finding that higher levels of inbreeding are associated with mid to late-term pregnancy loss, as well as reduced athletic performance.

Two years ago, a study was commissioned with Nottingham Trent University, supported by Weatherbys, to consider where the thoroughbred might be upon its journey to genetic consequence. You will not be surprised to know that since the 1980s this risk has been steadily increasing; on a scale of 1-10, with one being no risk and ten being an irreversible outcome, Britain is at five on the scale. While there is time to address the increasing problem, the industry must act now, as the pace of compromise increases with large book sizes, fewer mares being bred, and a smaller  population of available stallions.

Without intervention, this will be a severe problem in ten years’ time or possibly much earlier. To that end, James Crowhurst, a TBA Trustee and very experienced veterinarian, together with  Victoria Murrell from the TBA office are starting to develop a targeted pilot programme that will involve the use of the SPARKS software that has proved so successful with the Cleveland Bay. The thoroughbred is in a better position than most breeds as we have the General Stud Book as our reference and family tree, so we should get answers sooner.

Inevitably, behaviours and practises will have to change – certainly, the breeder of the next 25 years will make different decisions and be asked different questions than we have become used to. However, it is the breeding industry that has bought us to this point, and it is the same industry that must lead away from the prospects of an uncertain future for the thoroughbred.

The TBA has been engaged with this issue for some while and now it needs broadening to become an industry initiative. A problem must be recognised and understood first before it can be solved – this is a challenge that affects all of us and we need to talk about it.