Most performance horses are fed in a way that undermines them

How to feed a performance horse: what the evidence actually supports

Forage first, minimum thresholds, not targets

Here’s the thing about the horse’s gut: it’s built to be doing something almost all the time. Fermentation ticks away around the clock in the caecum and large colon, and the whole system works best when forage keeps coming. The evidence sets a hard floor, forage must make up at least 1.5% of bodyweight in dry matter daily, with at least 8 hours of foraging opportunity per day. For a 500 kg horse, that’s a minimum of 7.5 kg dry matter from hay or grass every single day. I’d treat that as a floor, not a goal. Gaps between forage meals beyond 6 hours are a documented risk factor for equine gastric ulcer syndrome (EGUS), a condition affecting 80-100% of racehorses in active training. If your horse is stabled, keep hay in front of him as close to around the clock as you can manage.

Alfalfa deserves a specific mention. Its higher calcium content and buffering capacity produce a measurably higher gastric pH and lower squamous ulcer severity compared with grass hay alone. If your horse is ulcer-prone, swapping some of his grass hay for alfalfa is a straightforward, evidence-backed move, no medication required.

Concentrates, hard limits per meal

No single concentrate meal should exceed 0.5% of bodyweight, roughly 2.5 kg for a 500 kg horse. If workload demands more total concentrate, split it across multiple meals at least 4 hours apart. The reason matters: starch that escapes the small intestine ferments in the hindgut, destabilising the microbial population, dropping pH, and opening the door to hindgut acidosis, laminitis, and colic. The numbers are clear, starch should not exceed 1 g per kg bodyweight per meal, with a total daily ceiling of 2 g/kg bodyweight.

Here’s a quick practical cheque: if your concentrate ration is making up more than 50% of total dry matter intake, you’re already in documented risk territory for laminitis, colic, and EGUS.

Choosing the right energy source

Not all energy is equal, and this is where a lot of performance feeding goes wrong. Fat provides approximately 2.25 times more digestible energy per unit weight than carbohydrates, and it delivers that energy without the digestive chaos associated with grain-based starch. Oil supplementation can contribute up to 20% of dietary energy after a proper acclimation period.

For horses who start well and fade, or who become difficult to manage on grain, shifting energy provision toward fat and high-digestibility fibre (alfalfa, sugar beet) is well supported by the evidence. Research on French Trotters found that horses on high-fibre, low-starch diets achieved the same performance over an 8-week training period as those on traditional high-starch diets, and maintained better gut health while doing it. That’s not a minor footnote; it challenges a lot of received wisdom about how performance horses need to be fed.

For any concentrates you do feed, look for products with starch and sugar content below 16.5%. In competing performance horses, this threshold has been shown to reduce gastric disease scores and improve faecal microbiota profiles, without medication.

Calibrating to the individual horse

Heavy work can push energy requirements up to 100% above maintenance, but fixed feed amounts are a blunt instrument. Body condition score, target 4-6 on a 9-point scale, is the best practical measure for whether your horse’s energy intake is actually correct. Watch the horse. Condition, behaviour under saddle, and energy levels tell you more than any feed chart ever will.

Duration and transition

The research on low-starch dietary modifications used competitive performance contexts, with measurable outcomes ranging from 10 days (herbal anti-inflammatory supplementation) to 8 weeks (fibre-based diet transitions). There’s no evidence in the pool to support a defined “loading period” for dietary changes beyond the standard advice to transition gradually, which the fermentation physiology clearly supports anyway.

When high-starch concentrate feeding is contraindicated

The research identifies specific situations where high-starch feeding carries documented risk:
– Any horse with a history of laminitis, hindgut starch fermentation is a direct trigger
– Horses diagnosed with or suspected of EGUS, starch above 1-2 g/kg per meal is a primary risk factor
– Horses showing behavioural signs of hindgut discomfort or ridden pain-associated behaviours

In these cases, switching to a low-starch concentrate (under 16.5% starch and sugar) alongside maximised forage provision is the evidence-supported approach.