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 (1).
With winter just round the corner and grass growth stunted by the UK’s arid summer, many horse owners are feeding hay or haylage earlier than usual. But simply giving horses hay may not be enough for optimum health, even if it meets their energy needs and requirement to chew.
A pertinent study published last year by WALTHAM®, who provides the science underpinning the SPILLERS® brand, in collaboration with Michigan State University, discovered that feeding a hay-only diet resulted in reduced digestibility of many micro and macro minerals (such as 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.
Clare Barfoot RNutr, the research and development manager at SPILLERS® said: “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. 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.”
(1) 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