British scientists have created a ‘family tree’ which has helped safeguard the genetic diversity of England’s oldest breed of horse, the Cleveland Bay, an endangered species.

Using the new ‘Breed Conservation and Management System’ (BCAS) which offers recommendations based on the horses’ genetic history, breeders can use a simple red, amber and green system depending on whether the horses are related and should. be raised.

It helped reduce the rate of inbreeding in Cleveland Bay horses from over three percent per generation to less than 0.5% per generation.

In addition, the effective population size in the UK – which takes into account unrelated breeding adults in any population – has increased from 20 in 1994 to over 140 in 2020.

The results of nearly 20 years of work by researchers at the School of Animal, Rural and Environmental Sciences at Nottingham Trent University have been published in the journal Ecology and evolution. The project focused on minimizing parentage between rare breeds by supporting breeders with historical information about the parentage of individual horses through their pedigree records. It also involved the University of Lincoln and the Cleveland Bay Horse Society.

The team says the system could be applied to other rare and endangered animal breeds to ensure their genetic status is maintained.

The consequences of poor breed and inbreeding management can lead to a variety of serious health problems in individual animals, including fertility issues.

Small animal populations, as well as larger unmanaged groups, can be in the throes of genetic regression, often due to a lack of easy-to-use selection aids that can help breeders to to take decisions.

The researchers argue that as a result of this work, the Cleveland Bay is now in a genetically sustainable position.

They say their population management tool could be applied to all captive species, from rare and endangered breeds to zoo animals and livestock.

The Cleveland Bay is an original British breed born three centuries ago in the North East of England, where it was used both as a carriage horse and for working the land.

Since the end of World War I, the breed has suffered a substantial decline due to modernization of transport and mechanization of agriculture.

By the 1950s it was close to extinction, there were only four purebred stallions left and it is currently one of seven equine breeds listed as priority by the Rare Breeds Survival Trust.

The Cleveland Bay Horse Society published its first herdbook in 1885, containing retrospective pedigrees of animals dating back to 1723; this now results in a non-thoroughbred studbook dating back almost 300 years and spanning 38 generations.

“What we have created is like a family tree for the horses of Cleveland Bay,” said Philippe Wilson, researcher at Nottingham Trent University.

“There are serious and growing concerns about genetic diversity in many breeds. Animals are bred for all kinds of commercial purposes and for particular traits and qualities, but once the genes are gone, they are gone forever.

“If we don’t have enough purebred individuals, or if a male in a small population breeds with many females, for example, it can have a deleterious effect on genetic diversity.”

16 years of management of the breed brings a substantial improvement in the genetics of the endangered Cleveland Bay horse population. Andrew Dell, Mark Curry, Elena Hunter, Ruth Dalton, Kelly Yarnell, Gareth Starbuck, Philippe B. Wilson. Ecology and evolution. https://doi.org/10.1002/ece3.8118