FEEDING STRAW AS A HAY ALTERNATIVE

The pros and cons

By Hannah Botha, MSc

Traditionally, most owners have not considered feeding straw to their horses. However, in these more difficult times and with parts of the country experiencing hay shortages, more and more are wondering about the option. But is it worth it? Does it make sense for some horses but not others? Or is it just a big no? In this article, we answer these questions and more.

Straw vs cereal hay

Straw is a by-product of cereal crops like oat, barley and wheat, which is cut after the grain has been harvested. Being more mature, straw has a higher proportion of indigestible fibres (such as lignin), making it lower in digestible nutrients. By contrast, cereal hay (oat hay, for example) is harvested when the grain is immature and the leaves and stems are still green, making the final product higher in digestible nutrients.

What type of straw is better for horses?

As with all roughage given to horses, any straw fed should be clean, hygienic, and mould-free. Straw can be more variable than hays as straw quality is less controlled, being a by-product of another process. The onus is then on the owner or manager to ensure that the straw chosen is of good quality. Oat and barley straws are generally softer with less indigestible fibre than wheat straws, so these are more commonly used for horses. Although not a scientifically proven method (!), one way to test the appropriateness of a straw is to scrunch it and observe its response. If it scrunches easily (stems are soft), this can indicate a more palatable and digestible straw for horses. Avoid cuts that are extremely coarse and have sharp ends, for example, bedding-type straw.

Does straw supply the nutrients my horse needs?

The nutritional value of different straws will vary according to the type as well as the environmental conditions it was grown in. On average, though, the straw will have a lower level of energy and thus calories, contain a lower level of digestible protein and have a variable non-structural carbohydrate level compared to grass hay.

Pros and cons

Straw is lower in calories compared to other forages. For this reason, it can be an ideal option for mixing with good quality hay to ‘dilute’ the calories supplied to good-doers/overweight horses and ponies. This is especially useful when it is hard to buy separate forage, such as on a stable yard where forage is provided as part of the stabling cost.

A recent study by Dosi et al., (2020) investigated feeding barley straw together with hay to overweight horses and found the group on the straw/hay diet had a significantly greater weight loss compared to feeding hay alone. The average weight loss was 27kg. Substituting up to 50% of grass hay in a diet with quality straw creates a less energy-dense ration while maintaining adequate forage intake. This means that intake does not need to be severely restricted to achieve weight loss. Restricting roughage intake can lead to not only digestive issues but behavioural ones too, so replacing some hay with straw is a great option. Another advantage of feeding straw alongside hay is that it extends the overall time horses spend eating per day. This helps to keep them satisfied and reduces the risk of gastric ulcers by ensuring they are not going for prolonged periods without food. Although straw has minimal buffering capability, unlike lucerne, it is still beneficial for gastric health because it increases chew time and therefore results in greater saliva production. Horses can only produce saliva when they chew, so more time spent chewing means more saliva is produced. This is important as saliva contains bicarbonate which helps to buffer acidity in the horse’s digestive tract. Chewing one kilogram of roughage would require roughly 3,500-4,500 chews vs only around 800-900 for concentrate feeds; thus, it is easy to see why a constant supply of roughage is ideal.

Another reason to feed straw is to lower the sugar and starch content of the diet. Research by Jansson et al., (2021a) showed that blood tests taken during the study indicated that plasma insulin levels were lower on a diet with straw compared to haylage, which could be beneficial for horses who are overweight or have insulin resistance.

However, it should be noted that while most straw is low in sugar and starch (around 2% non-structural carbohydrate, NSC), some can be as high as 17%, which is not suitable for horses with metabolic issues such as laminitis or insulin resistance. Ideally, straw should be tested for NSC content before use; however, testing of hays/straws can be difficult, so it may be worthwhile feeding grass hay that has a more predictable NSC range combined with soaking for a further reduction in NSC levels. Another tip if you do want to feed straw but are concerned about NSC values is to visually inspect the straw to ensure it doesn’t contain intact heads of cereal grains, which may make the straw higher in starch.

The biggest concern with feeding straws as a sole roughage source is that they are generally much lower in quality protein than grass or cereal hays. This means that straw would not be a viable alternative to hay for horses requiring higher levels of protein, such as lactating mares or growing youngsters. A further concern is that mineral levels are lower, and straw has virtually no vitamin value. Being higher in indigestible fibres, straw is a poorer support for the digestive microorganisms, which would normally produce B vitamins for the horse. As a result, straw might not help you reduce costs as additional supplements, like a balancer, could be needed to ensure that the horse receives all the daily essentials, especially if no concentrates are being fed.

To top it off, there is a higher risk of toxic nitrate levels in straw and a higher mycotoxin risk. Therefore, it is suggested that straw not be provided as the sole forage source but rather alongside other hays. Straw could be useful in helping to stretch hay in times of scarcity without vastly changing the nutrient value of the diet; however, it would be worth speaking to a nutritional advisor before changing to ensure your horse wouldn’t be missing out on any daily essentials.

Can straw cause gastric ulcers or colic?

Researchers in Denmark found that a horse eating straw as the sole or predominant forage source was 4.5 times more likely to develop gastric ulcers (Luthersson et al., 2009). For most horses, straw is rarely fed as the sole forage source, and it should be recognised that straw can be useful as a low-calorie forage source alongside hay for good doers. To assess the risk for these horses, a follow-up study by Jansson et al., (2021) investigated the safety of feeding 50% wheat straw and hay together.

The research found no increased risk of ulcers from using 50% straw to replace haylage in the ration. Three weeks is considered long enough for ulcers to develop and there is not currently any reason to suspect gastric ulcer issues are more likely to occur with the long-term use of straw when combined with other roughage sources. This is especially valid if it means more forage can be fed in total to avoid long periods without food.

Regarding colic risk, the study by Jansson et al., (2021b) also found that faecal dry matter content was not affected by diet, and no difference was detected in the number of intestinal sounds between the diets. Faecal water was also within normal ranges and did not differ between diets. To date, no research findings suggest a 50% inclusion of straw increases the risk of colic. However, care needs to be taken in choosing the right type of straw, and the straw should be introduced gradually over 14-21 days until a 50:50 ratio is achieved with hay to straw.

Conclusion

In summary, there is ample room for feeding straw, especially where a calorie-controlled diet is needed for long-term weight loss. However, this small reduction in calories comes with a much greater loss of protein, vitamins, and minerals compared to feeding hay, and so may require the inclusion of additional supplements in the long run, reducing the cost-saving potential for straw.

References

Miranda Carlotta Maria Dosi, Roxane Kirton, Sarah Hallsworth, John A. Keen and Ruth Anna Morgan. (2020) Inducing weight loss in native ponies: is straw a viable alternative to hay? Vet Record, http://dx.doi. org/10.1136/vr.105793

Jansson, A.; Harris, P.; Davey, S.L.; Luthersson, N.; Ragnarsson, S.; Ringmark, S. (2021a) Straw as an Alternative to Grass Forage in Horses—Effects on Post-Prandial Metabolic Profile, Energy Intake, Behaviour and Gastric Ulceration. Animals 2021, 11, 2197

Jansson, A., P. Harris, S.L. Davey, N. Luthersson, S. Ragnarsson, and S. Ringmark. (2021b). Straw as an alternative to grass forage in horses: Effects on post-prandial metabolic profile, energy intake, behaviour and gastric ulceration. Animals (Basel) 11(8):2197

Luthersson, N., Nielsen, K.H., Harris, P., Harris, T.D., Parkin, H. (2009) Risk factors associated with equine gastric ulceration syndrome (EGUS) in 201 horses in Denmark. Equine Veterinary Journal, Vol: 41, Issue 7., p625-630