Scientists have already linked the peroxisomal acyl-coenzyme A oxidase 1 (ACOX1) gene to racing success in Arabians and Thoroughbreds. ACOX1 appears to slow the body’s use of fatty acids to generate energy, making the process more efficient and providing energy over a longer period. Now they’ve also found that ACOX1 appears in some wild and feral breeds—which need efficient energy production to prevent starvation in difficult environments—but in a different form, said Katarzyna Ropka-Molikk, PhD, of the Department of Animal Molecular Biology in the National Research Institute of Animal Production, in Balice, Poland.

Ropka-Molikk and her fellow researchers analyzed DNA from more than 600 horses representing five breeds: Arabians, Thoroughbreds, Polish draft horses, and two hardy native breeds—the Polish Konik and the Hucul. They identified two critical variants of ACOX1, a G allele variant and a T allele variant. Racing horse breeds (Arabian and Thoroughbred) were more likely to have the T allele variant, whereas the three other breeds were more likely to have the G allele variant, Ropka-Molikk said.

“In our new study, we wanted to check how these variants are distributed across the population of horse breeds being under different selection pressures,” she said. “The Polish Konik is classified as a primitive, modern relict of the past feral population of forest ponies.  Moreover, we used two Warmblood breeds which were characterized by extremely different ACOX1 genotype frequency. At this stage of research, we cannot clearly say if this gene is a ‘performance’ or ‘survival’ gene, but the results obtained strongly indicated its association with the selection toward different utility types in horses.”

ACOX1 might even have a link to atypical myopathy, she said, as the gene codes for the protein affected by the maple tree seed toxin. However, further research needs to look deeper into that theory.

For the moment, the work is preliminary, but it points critically to the role ACOX1 might play in energy metabolism that contributes to the different needs of certain breeds, said Ropka-Molikk. “Our research, focused on ACOX1 gene, showed that its genetic variants can be related to racing ability and maybe other phenotypic traits in horses as well,” she said. “The present report can be a great preliminary study focused on new markers in horses and sets the directions for further research in this area.”

ACOX1 research in horses is ongoing, she added. “We encourage (breeders, veterinarians, and other scientists) to follow the news on this topic,” Ropka-Molikk said.