How has horses' feed changed? Thoroughbred Nutrition Past & Present
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By Catherine Rudenko
Feeding practices for racehorses have changed as nutritional research advances and food is no longer just fuel but a tool for enhancing performance and providing that winning edge.
Whilst feeding is dominantly considered the content of the feed bucket, which by weight forms the largest part of the horse’s diet, changes in forage quality have also played a role in the changing face of thoroughbred nutrition. The content of the feed bucket, which is becoming increasingly elaborate with a multitude of supplements to consider, the forages—both long and short chop and even the bedding chosen—all play a part in what is ‘the feed program’. Comparing feed ingredients of the past against the present provides some interesting insights as to how the industry has changed and will continue to change.
Comparing key profiles of the past and present
The base of any diet is forage, being the most fundamental need of the horse alongside water. Forage quality and form has changed over the years particularly since haylage entered the market and growers began to focus specifically on equine. The traditional diet of hay and oats, perhaps combined with mash as needed, provided a significantly different dietary intake to that now seen for horses fed a high-grade haylage and fortified complete feed.
Traditional Diet
7kg Oats
1kg Mash – comprised of bran, barley, linseed and epsom salt
0.5kg Chaff
Hay 6% protein consumed at 1% of bodyweight
Modern Diet – medium-grade haylage
8kg Generic Racing Mix
0.5kg Alfalfa Chaff
60ml Linseed Oil
60g Salt
Haylage 10% protein consumed at 1% of bodyweight
Modern Diet – high-grade haylage
8kg Generic Racing Mix
0.5kg Alfalfa Chaff
60ml Linseed Oil
60g Salt
Haylage 13% protein consumed at 1% of bodyweight
The traditional example diet of straights with bran and hay easily met and exceed the required amount of protein providing 138% of requirement. When looking at the diet as a whole, the total protein content of the diet inclusive of forage equates to 9.7%. In comparison the modern feeding example using a high-grade haylage produces a total diet protein content equivalent to 13.5%. The additional protein whilst beneficial to development, muscle recovery and immune support can become excessive. High intakes of protein against actual need have been noted to affect acid base balance of the blood, effectively lowering blood pH (1). Modern feeds for racing typically contain 13-14% protein which complement forages of a basic to medium-grade protein content very well; however when using a high-grade forage, a lower protein feed may be of benefit. Many brands now provide feeds fortified with vitamins and minerals designed for racing but with a lower protein content.
Whilst the traditional straight-based feeding could easily meet energy and protein requirements, it had many short-falls relating to calcium and phosphorus balance, overall dietary mineral intake and vitamin intake. Modern feeds correct for imbalances and ensure consistent provision of a higher level of nutrition, helping to counterbalance any variation seen within forage. Whilst forage protein content has changed, the mineral profile and its natural variability has not.
Another point of difference against modern feeds is the starch content. In the example diet, the ‘bucket feed’ is 39% starch, a value that exceeds most modern racing feeds. Had cracked corn been added or a higher inclusion of boiled barley been present, this level would have increased further. Racing feeds today provided a wide range of starch levels ranging from 10% up to the mid-thirties, with feeds in the ‘middle range’ of 18-25% becoming increasingly popular. There are many advantages to balancing starch with other energy sources including gut health, temperament and reducing risk of tying-up.
The horse with a digestive anatomy designed for forages has limitations as to how much starch can be effectively processed in the small intestine, where it contributes directly to glucose levels. Undigested starch that moves into the hindgut is a key factor in acidosis and whilst still digested, the pathway is more complex and not as beneficial as when digested in the small intestine. Through regulating starch intake in feeds the body can operate more effectively, and energy provided through fibrous sources ensures adequate energy intake for the work required.