We tend to think of hay being made in preparation for the coming winter, but hay is useful, and indeed necessary, all year round, even when your paddocks are full of grass.
In this article, we will look into several reasons why hay is so important for horses, and why it is sought after even when pasture is plentiful.
To do this, we need to discuss the nutrient content of grass compared with hay, and what the difference is between the two forms of forage. We’ll look at when hay can be helpful, consider lucerne hay, and finally, discuss the disadvantages of hay.
Grass v hay
The obvious way to feed a horse or pony is to allow them to graze pasture, especially when there is plenty of grass around. Wild horses eat grass, it should be simple! However, there is a huge difference between the rough natural grass that wild horses have access to and the highly cultivated grass most of us tend to have in our paddocks.
In the wild, horses travel relatively large distances each day to get all the food they need, and they have a good selection of plants and grasses to graze. They may well find it easier to eat all their energy needs in the spring and summer and so put on weight, and these fat stores are broken down and used over the following winter to keep them going when food supplies are scarcer. It is a natural cycle.
In contrast, our domestic horses often have very easy access to all the food they can eat. Our cultivated paddocks provide easy grazing of higher-energy grass, our horses don’t have to travel very far to eat, and in winter (seeing we don’t like them to lose weight) we use extra feed and covers to prevent this happening.
Often, our paddocks have been sown in one main type of grass, usually ryegrass (with clover) although there is a recent trend to sowing horse paddocks back into a mixture of older, more horse-friendly grasses.
Isn’t hay just dried grass? Why is it different?
Yes, hay is dried grass that has been baled to preserve it for feeding at a later date. However, there is a lot less moisture in grass; therefore it has a higher dry matter content. The nutrient content, particularly the non-structural carbohydrates (NSC), (see below for more information on this) changes, depending on what stage of growth the grass was harvested, the time of day the grass was mown, the season, whether it was rained on, how much sunlight there was and and even how long after being mown it was baled.
You can test hay for its NSC content, so you can reduce it, if necessary, by soaking (for more on this, see under laminitis heading).
The NSC of pasture, on the other hand, is very variable. It changes all the time throughout the day and night, depending on temperature, sunlight and availability of water.
In ideal situations, grass and plants make sugar by way of photosynthesis throughout the day, so NSC levels increase as the day goes on. They then use the sugar for growth overnight, and so NSC levels are reduced by the morning (as long as conditions are favourable for overnight growth).
Stress, cold and drought can all change this cycle and affect the NSC levels of pasture, so it can be hard to predict.
Why are NSC [non-structural carbohydrate] levels so important? Isn’t more energy better, and the point of food? To answer this, we need to think about how the horse digests and uses the feed it eats.
Carbohydrates, fibre and NSC
Carbohydrates can be broken down in the two separate parts: structural and non-structural. Structural carbohydrates are what we call fibre or roughage, and non-structural carbohydrates are the sugar and starches.
Horses (and ponies) need fibre! Whether they are paddock pets or high-level competition athletes, they all need fibre. They also need other carbohydrates, protein, fat, vitamins and minerals, and water. But at the very minimum, 1% of their bodyweight should be eaten in fibre-based feed every day, and ideally more like 1.5-2%.
It can be hard to understand how a horse can get much energy from eating fibre. As humans, we tend to relate it to being told to eat lots of salad. Thus, we think of high-fibre foods as being low in calories.
However, the digestive system of a horse is different to our own; they have a very well-developed large intestine (hindgut), which is their large colon and caecum. A 500kg horse’s large colon measures 3-4 metres long and holds around 100 litres! Their caecum can hold around 30 litres. These huge structures also contain billions of bacteria and protozoa, together known as microbes.
Bacteria are, of course, very tiny, and protozoa are microscopic animals made up of only one cell. Together, in large numbers, these microbes are capable of breaking down the structural carbohydrates (fibre) found in hay etc to produce an energy source which is absorbed through the intestine, and is then available for the horse to use.
This way, horses are able to get a lot of energy (calories) from fibre, and it is very important that they have plenty of it, to keep this population of tiny microbes healthy and thriving.
Sugars and starches
Sugar and starches are found in higher concentrations in grains (oats, maize, barley etc.), although they are very much present in grass and hay too, and as we discussed, the levels in grass change through the day and night. The non-structural carbohydrate can be digested directly by the horse, mainly in the small intestine which food passes through before reaching the large intestine. So, they provide a more rapid source of energy directly into the bloodstream.
This is very important to consider for laminitis-prone horses and ponies, as the measurement most commonly used to help decide if a feed is suitable for laminitic horse and ponies is the non-structural carbohydrates’ NSC percentage.
Disadvantages of hay
Hay is great, but there are a few potential downsides to watch out for.
Spoilt hay. There is a potential for hay to go mouldy if it is not made or stored properly. Do not feed mouldy hay.
Allergies. Hay can contain dust and mould spores to varying amounts. A horse eating hay will be breathing these in continually as they are eating (as their nostrils are right in the hay) and for some horses this will cause inflammation in the lungs, with coughing and even wheezing as the airways become narrowed. To reduce this risk, dampening or steaming hay is a good option. This is different to soaking hay, as we don’t necessarily want to change the nutrients by soaking for a period of time, we just want to reduce the dust particles in the air around the hay. (Talk to your vet if your horse shows any of these signs).
Colic. Any change in diet leads to an increased risk of colic. So, try to introduce the feeding of hay gradually if possible. Secondly, make sure there is easy access to all horses to fresh water – if they eat a large amount of hay without drinking there is increased risk of an impaction colic.
More work. Finally, of course feeding hay is more work than just letting your horse graze! However, everyone wants to do the best for their horse or pony so if the benefits outweigh the disadvantages, this is not likely to be an issue!
