Daily feed intake
One of the simple pieces of information uncovered in Owens' study was the potential importance of daily feed intake. She found
that eventing horses consumed an average of between 1.48 and 2.45 percent of their body weight, dressage horses consumed between
1.04 and 1.79 percent, while show jumpers consumed between 1.09 and 2.55 percent. This is significant because it points out
that not all elite equine athletes are alike, and horses from different disciplines have different daily feed intakes (Photo
Photo 3: A horse training in the Kentucky Horse Park before the 2010 Alltech FEI World Equestrian Games held in October in
Lexington, Ky. Horses competing in different disciplines require differing food intake percentages.
The National Research Council (NRC) suggested daily intake for working horses is between 2 percent and 3 percent of body weight.
A study of 25 racing Thoroughbred and Standardbred stables showed good correlation to NRC-suggested intakes, but it becomes
clear that requirements vary for differing breeds and disciplines.
"These results illustrate how important it is for each horse to be fed as an individual and why it is sometimes necessary
to be critical of feed manufacturers' recommendations for feed allowances," says Owens. Not taking these subtle, but important,
differences in intake need into consideration might result in unwanted weight gain, reduced performance and reactions to increased,
unneeded protein or carbohydrates such as skin bumps or urticarial reactions, changes in manure consistency and behavioral
problems (excessive activity, anxiousness and inattentiveness).
Body weight is another detail that can have significance for the elite performance horse. Decreases in weight can be an early
indicator of a problem, with possible causes ranging from training concerns to medical or lameness issues to physiological
or stress factors.
A study done by Susan Garlinghouse, DVM, MSc, at the 1999 Tevis Cup 100-mile endurance ride showed a strong correlation between
body condition score (BCS) and the ability to successfully finish the race. Non-finishing horses had an average BCS of 2.9,
while BCS for the finishers averaged 4.5.
Horses that are training well and improving condition generally have good appetites and stable to slowly increasing body weights.
Overtrained and stale horses will not eat well and may show subtleties in weight loss, if riders and trainers look for them.
"Generally, riders are not aware of the actual weights of their horses, nor the normal range for variation of those body weights
in response to work intensity, climate or feed changes," Owens says.
To achieve the ultimate goal of ensuring that the performances of Australia's equine athletes are not being limited by suboptimal
nutrition, it was important in Owens' study to evaluate the feeds and supplements being used and to determine any dietary
deficiencies. Of the 22 horses investigated in her study, only one eventer and three dressage horses were deemed balanced
and, therefore, received no additional vitamin or trace mineral supplementation.
In contrast, 17 of the 22 were receiving inadequate levels of vitamin E (< 1,000 IU/day). Because vitamin E is important in
its role for muscle function, it is easy to see how small changes or deficiencies can contribute to suboptimal performance
and a horse that is simply not working to its potential. Nine horses were receiving sodium at a level significantly lower
than the NRC recommendations, and four others were deficient in other minor vitamins.
The take-home message
It is worth noting that this study was done among the best equine athletes in a nation that is currently one of the top sport-horse
countries in the world. This is an extremely successful program, and yet there are still some areas for improvement.
"While some of the participants in this study had a clear grasp of the principles of basic equine nutrition, several were
confused about feeding and viewed nutrition as a low priority in the performance of their horses," Owens says.
It brings into question how much nutritional knowledge and attention exists in the smaller, less elite and less successful
programs that veterinarians consult with routinely. Encouraging clients to learn about and integrate new nutritional information
and high-quality feeds and supplements into their established feeding programs is one area that veterinarians can still make
a significant contribution to the performance of the equine athlete.
Dr. Marcella is an equine practitioner in Canton, Ga.