Susie Sharp
The Foal Project The yearling Fed Biz—Miss Bravo colt (above, and at left with Mary Lou Griffin) munches away in the shed-run at the Buckley-based Griffin Place.
Susie Sharp
Part 6 – Growing Up Thoroughbred by Susie Sharp
T
he foals are now playful and curious yearlings. With room to run, plenty of food, shelter and pasture buddies, their lives continue to be very natural. Growing up to be a healthy and sound Thoroughbred requires a harmonious balance of many factors. The goal and challenge for the breeders and owners are to make the process as smooth as possible. Merriam-Webster’s definition of growth is “a stage or condition in increasing, developing, or maturing.” However, if the dictionary were to define the reality of raising a Thoroughbred, the following factors would need to be included: • Birth month • Season • Sex • Diet and growth rate • Bloodlines • Country Raising Thoroughbreds is far more complicated than the rural surroundings belie. Research has looked at a multitude of factors to try and identify which factors make for a healthy, well-sized and sound athlete. The answers are complex and fascinating. 30
Birth Month and Seasonal Factors It is common knowledge that Thoroughbreds have the same technical birthday. In the Northern Hemisphere, Thoroughbreds turn one year older on January 1, whereas in most, but not all, of the Southern Hemisphere the recognized date is August 1. Breeding cycle differences by hemisphere account for the respective dates.1. A universal birthday enables breeders and owners to race horses of comparable age. Hence the earlier the actual birthday, the bigger and more developed a young horse is, in theory, and the better he/she is likely to perform in both the sales ring and on the track. Research by Huntington, BrownDouglas, and Pagan (2020) confirms that birth month influences birth weight and the anticipated average daily growth (ADG) over time. Typically, the weanling experiences a drop in weight, and the ADG is impacted negatively by winter conditions.2,3 Kentucky Equine Research (KER) conducted a longitudinal study (199395) of 700 foals. The results were as
follows: “Compared to March foals, foals born in January and February were 6.8 kg lighter at 14 days of age. They remained smaller until about nine months of age when they averaged about the same as the March foals. April and May foals were larger at 14 days of age than March foals, and remained slightly heavier until six months of age. Average daily gain (ADG) among the four groups was similar until about seven months of age. ADG was 1.5-1.7 kg/d during the first month and declined linearly to about 0.70-0.80 kg/d at seven months of age. After seven months of age, ADG tended to be more variable and by 12 months, ADG was very different between the different months of birth. Foal growth rates were reduced during the winter months regardless of when the foals were born and increased during April and May of the foal’s yearling year. Growth rate in these yearlings was more a function of season of the year than age.”4 Huntington, Brown-Douglas et al. further conclude that there are seasonal impacts to the ADG of young Thoroughbreds. In particular, ADG increased as a result of Washington Thoroughbred
