Horse owners have been adding chaff to meals to extend eating time for decades but have you ever wondered if it actually works? New research published by Charles Sturt University in collaboration with SPILLERS™ and our Director of Science, Pat Harris, set out to answer this very question…

Photo by Bethany Grace Photography


The all-important results

In order to put this common feeding practice to the test, researchers fed oats on their own and oats in addition to varying amounts of straw chaff in a random order. As the length of chaff commonly fed to horses varies between countries, researchers also tested the effect of feeding a short chop (approx. 1.5cm) vs. a long chop chaff (approx. 4cm). Regardless of chop length, adding 15% chaff e.g. 300g of chaff to 1.5kg oats, significantly increased eating time. As you might expect, horses ate more slowly when greater amounts of chaff were added although the effect plateaued at 50%.


Why is this important?

We all like to see our horse’s enjoying their feed but rapid intake of meals may lead insufficient chewing, reduced saliva production and food passing through the digestive system too quickly which in turn, may lead to conditions such as choke and colic. Saliva, which is only produced when the horse chews, also provides a natural buffer to stomach acid. Having evolved to spend 16-18 hours per day foraging, horses have a psychological need to chew which means feeding short chopped fibre may be of added benefit to horses on restricted rations of forage.


All in all, feeding short chopped fibre can be a great way of helping to support your horse’s digestive health and mental well-being.


Other findings

In follow-up researchers then set out to identify other factors that may affect eating time by feeding oats without chaff in three further studies. Whilst the speed at which horses ate (grams per minute) was not affected by meal size, the addition of molasses, gender, age or exercise, it was affected by breed. Clydesdales ate significantly faster than TB’s and SB’s of a similar bodyweight. One possible reason for this might be that breeds with a larger head/ jaw such as the Clydesdale may be able to consume more feed in each mouthful. Regardless of breed, horses were also found to eat more quickly at the start of meal.


Want to know more?

This research is published in the Journal of Equine Veterinary Science.



Campbell TE, Doughty H, Harris PA, de Laat MA, Sillence MN. Factors Affecting the Rate and Measurement of Feed Intake for a Cereal-Based Meal in Horses. J Equine Vet Sci. 2020 Jan; 84:102869. doi: 10.1016/j.jevs.2019.102869. Epub 2019 Nov 22. PMID: 31864455.

SPILLERS has a comprehensive range of fibre feeds to suit all horses and ponies; including products designed to extend eating time to those complete with vitamins and minerals which can be fed as a total hay replacer.

For more advice on choosing a suitable chaff/ short chopped fibre for your horse contact the SPILLERS Care-Line via 01908 226626, or fill in our nutritional enquiry form here.