Research has shown that horses on a hay-only diet may not digest some nutrients as effectively as those fed combination diets and could benefit from dietary supplementation.
Horse owners who are short of other feed, and those who are dieting their equines may not be providing their horses with enough micro and macro minerals, even if it meets their energy needs and requirement to chew.
A study published last year by Waltham, which provides the science underpinning the Spillers feed brand, in collaboration with Michigan State University, discovered that feeding a hay-only diet resulted in reduced digestibility of calcium, magnesium, copper and zinc.
The study involved a group of healthy adult horses and a group of healthy aged horses being randomly assigned on a rotational basis to one of three diets that supplied similar gross energy over a five-week period: hay, hay plus a starch and a sugar-rich concentrate or hay plus an oil and fibre-rich concentrate. The micro and macro nutrient digestibility was determined for each diet.
An analysis of faecal and urine samples showed that while the horse’s ability to digest key nutrients does not appear to decrease with age across any of the three diets fed, the hay diet was lower than the other two diets for fat intake, amount digested and percent of apparent digestibility. However, perhaps most importantly the apparent digestibility for various macro and micro minerals (including key trace elements) was consistently lower when fed the hay diet compared with the other two diets.
“It seems that many micro and macro minerals are less available to the horse from a hay only diet than when the hay is fed together with a fortified feed,” said Spillers research and development manager Clare Barfoot.
“This strongly suggests that horses and ponies fed hay only diets may require additional supplementation such as a balancer to maintain good health and well-being.”
Comparison of nutrient digestibility between three diets for aged and adult horses (2017) Sarah Elzinga, Brian D. Nielsen, Harold C. Schott, Julie Rapson, Cara I. Robison, Jill McCutcheon, Ray Geor and Patricia A. Harris. Journal of Equine Veterinary Science, vol 52 p89