Measuring Height and Weight of Foals

Waves of anticipation and excitement surround foaling season as a new crop of foals makes its way into the world.  Spindly-legged and helpless one day and robust and independent the next, foals mature quickly. How can mare owners be sure their foals are growing to specs, fulfilling the genetic promise of their sires and dams?

Tracking the growth of foals weekly from birth is the best way to ensure slow, steady growth, according to Eileen Phethean, technical consultant for Kentucky Equine Research’s growth-monitoring software Gro-Trac®. “Though Gro-Trac is used as a management tool on large breeding farms around the world, the importance of recording growth is just as applicable to breeders with just one, two, or three mares,” she said.

Experienced breeders can often tell when a foal is not growing or thriving to expectations, but even these people find themselves doubting their impressions from time to time.

“From my perspective, the primary reason for horse breeders of all stripes to track the growth of their foals is to provide them with quantifiable data about weight and height gain so they have a reliable backup for day-to-day eyeballing,” explained Phethean. “This would allow for a more rapid and subtle response to growth slowdowns before the deficit becomes significant and glaringly obvious.”

For small breeders, it might be especially interesting to track the height and weight of foals from month to month and then compare that data each year. “A lot of mare owners keep information about length of gestation or foaling peculiarities, and they do this because mares will frequently stay loyal to a pattern of behavior. The same consistency might carry over to growth of their foals. Some mares seem to always have large, fast-growing foals, for example. If a mare’s foal is well outside the norm for her, it might be cause to take a closer look at management,” said Phethean. Other factors could be at play as well, including different sire genetics. “Tracking growth provides breeders with another tool to raise healthy foals.”

In the fast-paced world of sales and shows, why are nutritionists insistent on moderate growth?

Maintaining smooth, steady growth can help reduce the risk of developmental orthopedic disease (DOD), which is associated with overconditioned, heavy foals growing too quickly or a period of rapid compensatory growth after a slump. On the contrary, insufficient caloric consumption may lead to small, underconditioned foals that will not achieve their genetic potential.

Spotting changes in the young horse’s growth pattern can provide early warning for foals that need to be more closely managed. Sometimes, the necessary management changes are easily implemented. For instance, herd dynamics within a group of youngsters might result in an individual being bullied out of its feed so that weight gain slows. This may not become apparent visually to someone that sees the horse every day as the daily change may be miniscule, but the change in slope of the weight graph may be more obviously spotted and prompt the owner to take measures to counteract growth slumps before the lack of weight gain becomes serious.

On the flip side, if sudden weight gain is noticed in foals, then managers can reduce feed, or be on the lookout for signs of DOD such as physitis. “Oftentimes, this can happen when forage stands remain better than average in the fall and winter, or when spring forage comes on faster than the supplemental hay ration is decreased,” noted Phethean.

Over the last two decades, KER and its consultants have gathered growth data on thousands of foals across the globe, and this databank can be useful for breeders. “If a breeder is producing a type of horse that we have a lot of data on—for example, Thoroughbreds—then our program Gro-Trac  also helps provide a target for growth and a benchmark so that he knows how his young horse compares to the population without having the benefit of the larger farm population to visualize differences,” she explained. “If a producer is breeding one or two or even five Thoroughbreds, he probably doesn’t have a large enough population of similar age to notice if one is bigger or smaller than average. Having a tool that tells an owner how his horse stacks up against the population can help him value his horse and make plans for its future, such as when to market the horse.”

Learn more about Gro-Trac.