Straw can be a very useful forage for horses because it is lower in energy (calories) than grass forages, so it can reduce calorie intake without restricting the total amount of forage. Its high fibre content also promotes satiety (a feeling of fullness) and it seems to slow the appetite.
This in turn can improve welfare and well-being for horses and ponies with low energy requirements. Clare has recommended feeding clean straw as up to 30% of the total forage ration for years, after seeing very good results - and almost no unwanted side effects - with client's horses and ponies.
Research into feeding straw
In a study by Mostert and colleagues (2024) investigating chewing rate and consumption rate of haylage versus a 50:50 mix of haylage and straw, after one week, horses fed the straw mix had a significantly slower consumption rate and a higher chewing rate compared to those fed all-haylage.
Dosi and colleagues fed a 50:50 mix of hay and straw to 25 horses and ponies to supplement poor pasture over winter, and hay alone to 15 others, all of whom were kept on similar pasture. Every individual in the hay/straw mix-fed group lost weight with a mean change of 27 +/- 17kg, whereas in the hay-fed group, only 3 out of 15 lost weight, and overall they gained weight (+6+/- 18kg). The researchers reported no episodes of colic or laminitis in either group, during the study period.
There has been some concern about feeding straw after a research study showed an association with an increased risk of gastric ulcers in horses fed straw as the only forage. The authors suggested that this may be due to mechanical damage, changes in fibrous “mat” in the stomach, and/or a reduction in buffering (acid reversing) capacity due to the low calcium and protein content of straw.
The authors of a more recent study showing the safety of replacing 50% of the forage ration with straw proposed that and alternative explanation might be possible, including hygienic quality - since straw can be low in hygienic quality i.e contain large numbers of mould spores and/or mycotoxins, which are likely to impact the gut.
In this more recent study, Jansson and colleagues (2021) showed that feeding half the forage as straw (with the other half grass haylage) had no detrimental effect on the stomach, did not increase the risk of gastric ulcers, and both prolonged feeding time and had beneficial effects on insulin profile.
The authors used a good hygienic quality wheat straw in the study. It was a small trial and they did recommend further work, but they concluded that 'including straw as part of the ration therefore may improve welfare for horses with low energy requirements' and that 'the wheat straw did not cause gastric ulcers'.
How to feed straw
If you are considering feeding straw to downgrade the energy (calories) of your horse's forage, then ideally source unsprayed, 'clean' straw. By 'clean' we mean good hygienic quality - it is bright and yellowy-orange in colour, which indicates it will have a lower mould count than a darker, most dusky looking straw.
You can feed up to 30% of your horse's total forage intake as straw (or 50% if you feed haylage), providing you introduce it gradually, give free access to clean fresh water and your horse's teeth are healthy.
Be aware that, although straw is lower in energy (calories) and much higher in fibre than hay, and is usually much lower in sugar, it can occasionally be as high in sugar than a typical hay (Jansson cited Tishler and colleagues, 2015, who reported up to 13% sugar in wheat straw).
Introduce and increase the amount of straw very gradually, to ensure that your horse or pony's digestive tract has time to adapt to the different type of forage. The healthy gut microbes (the microbiome) needs time to adapt to a more lignified, less digestible fibre.
You can feed the straw however you like: e.g. mixed with hay or haylage to encourage browsing, in a separate net, on the ground, or in clean banks around a bed. Like any forage, it needs to be kept dry (or eaten within 12 hours of being soaked) or it will mould and become unsafe, and unpalatable.
For horses or ponies with equine asthma (allergic to dry forage, prone to cough), the straw will need to be soaked for 15 - 20 minutes, or steamed before feeding.
If clean, feed quality straw cannot be found, a bagged alternative can be fed instead. Some of the low calorie, straw or straw-based chopped blends can be used as an alternative to 'long' straw, including TopSpec TopChop Zero, Honeychop Oat Straw or Dengie MeadowLite with Herbs.
Straw feeding tips:
1. Ensure your horse has good dental function and can chew well
2. Ensure free access to fresh clean water
3. Introduce gradually allowing the gut time to adjust - over 10-14 days for a third of the horse’s forage
4. Feed up to around a third (30%) of the daily forage ration - includes hay, haylage, straw
5. Choose clean, bright-coloured (ideally unsprayed) straw (oat, barley or wheat)
References
Dosi et al (2020) Inducing weight loss in native ponies: is straw a viable alternative to hay? Veterinary Record, 187 (8) p.e60-e60. doi.org/10.1136/vr.105793
Jansson et al (2021) Straw as an alternative to grass forage in horses - effects on post-prandial metabolic profile, energy intake, behaviour and gastric ulceration. Animals, 11; 2197. doi.org/10.3390/ani11082197.
Mostert et al (2024). A Preliminary Study on Feeding Straw to Horses and Its Effects on Equine Chewing and Consumption Rates. International Journal of Equine Science, 3(2), 115–122. https://doi.org/10.64292/ijes.128