However, a new study suggests the trocha isn’t all that genetically similar to lateral gaits in other ambling breeds like Icelandics, Tennessee Walking Horses, and pacers. While the gaitkeeper gene (DMRT3) appears to have some influence, the trocha appears to be coded by additional genes as well, said Miguel Novoa-Bravo, PhD of the National University of Colombia Department of Biology, in Bogotá.
In fact, he and colleagues from the Swedish University of Agricultural Sciences, in Uppsala, found the trocha actually has a diagonal component in it in addition to the lateral one, which might explain why the gaitkeeper gene only has a partial influence.
“The trocha is a lateral sequence four-beat gait, but it’s actually diagonally coupled,” Novoa-Bravo said, adding that the Missouri Foxtrotter’s foxtrot is similar to the trocha. “That means the forelimb hits the ground before the contralateral hind limb. So it has to be considered a diagonal gait, mainly because the time it takes to perform the diagonal movement (opposite fore-hind limb sequence) is shorter than the time it takes to perform the lateral movement (hind-fore limb of the same side).
In their study, Novoa-Bravo and his fellow researchers investigated the three Colombian Paso Fino gaits:
- The paso fino (a lateral-sequence four-beat gait);
- The trocha; and
- The trot (a two-beat diagonal gait).
They used biomechanics software and video recordings of nearly 200 horses with 13 markers placed on specific parts of the body to calculate speeds, angles, and movement of the horses’ legs during each of the three gaits. They also ran genetic testing to look for genes that appeared to correspond to the horses’ ability to perform these gaits.
They developed, for the first time, detailed biomechanical descriptions of each gait, Novoa-Bravo said. Knowing these details will help develop more strategic breeding programs and further their scientific understanding of this breed as well as of equine locomotion in general, he added.
They also found that the DMRT3 gene plays no major role in controlling the trocha or trot, said Novoa-Bravo—few of these horses carried the gaitkeeper gene and they weren’t homozygous (having two copies) for it.
However, the gaitkeeper gene is “clearly fixed” in horses capable of performing the paso fino gait, he said. These horses are mostly homozygous for the DMRT3 gene which likely allows them to amble.
“The gaits in the Colombian Paso horse breed are different from other lateral gaits (such as the tölt) in other breeds because the stride frequency is higher and the stride length is shorter than other gaits,” Novoa-Bravo said. “And often, there are three limbs (at least two for the Colombian Trot gait) in stance phase at the same time, which is what makes this horse one of the smoothest gaited horses.”
Their research into the kinematics and especially the genetics of different equine gaits is ongoing.
The study, “Selection on the Colombian paso horse’s gaits has produced kinematic differences partly explained by the DMRT3 gene,” was published in PLoS ONE.