Equine Nutrition Calculator

The calculator scales dry matter intake from 1.5% of body weight at maintenance up by 0.3 percentage points per activity level, reaching 2.7% at very heavy work. A harder-working horse needs more total energy, and since each kilogram of hay or concentrate can only supply so much digestible energy, the horse physically has to eat a larger volume of feed to meet that higher requirement rather than just eating the same amount more efficiently.

DE Balance is DE Provided minus DE Required, so a negative number means the ration you described — at your chosen hay type and concentrate percentage — doesn't supply enough digestible energy for the horse's body weight and workload, and the horse would need more feed volume or a higher concentrate percentage to close the gap. A positive balance means the ration is running a surplus, which over time can lead to unwanted weight gain if left unadjusted.

The calculator uses roughly 2.0 Mcal DE/kg for grass hay, 2.4 for alfalfa, and 2.2 for a 50/50 mixed hay, reflecting alfalfa's naturally higher energy and protein content compared to grass hay. Because energy-dense alfalfa supplies more Mcal per kilogram fed, switching hay types at the same feeding rate changes how much total energy the ration delivers even if the pounds of hay stay identical.

A horse's digestive tract evolved around a forage-based diet, and replacing too much of that forage with grain concentrate risks hindgut acidosis and colic. The calculator accepts a concentrate percentage input up to a 60% cap, but it does not itself enforce a lower practical ceiling, so staying comfortably under 50% in real feeding decisions is a judgment call left to you and your veterinarian or equine nutritionist.

They're drawn from the National Research Council's "Nutrient Requirements of Horses" (Sixth Revised Edition, The National Academies Press), the standard reference used across the equine nutrition field for maintenance digestible energy, work-level activity multipliers, and crude protein requirements. These are population-level published estimates, not a substitute for individualized guidance from an equine nutritionist -- especially for horses with metabolic conditions like equine metabolic syndrome or PPID.