Roughage should form the foundation of every horse diet. It provides the majority of your horse’s fibre requirement. Depending on plant maturity and quality, roughage can provide all or most of a mature horse’s protein requirements. It can often provide enough calories to maintain body condition and is often the key ingredient overlooked but much needed for weight gain. On the other end of the scale, people caring for overweight or insulin resistant horses are very aware of the need to limit pasture access, instead providing low sugar roughage to keep their horses healthy.
Why is roughage important?
The first rule of good horse nutrition is to feed plenty of roughage because the horse gut evolved to continuously ingest and digest the fibre contained in roughage.
The bare minimum amount of roughage required by a horse is 1% of its own bodyweight in DRY MATTER. Horses with access to lots of fresh pasture will happily graze for the majority of the day to consume their daily requirement of dry matter. They will also drink less water when grazing lush pasture because the grass has a high water content.
Unfortunately, horse owners rarely have access to unlimited good quality pasture and many horses kept in over-grazed paddocks, stables and yards do not get enough roughage. To keep horses healthy in yards, stables and smaller paddocks, they must be fed preserved grass in the form of hay, silage or chaff when fresh grass is limited.
Hay-reliant horses can consume their daily dry matter requirement in a relatively short period of time. Ideally, horses should have access to roughage at least 20 hours a day. There can be severe mental and physical health impacts when horses do not get enough roughage.
Because horses evolved with constant access to grazing, the horse stomach secretes acid continuously, unlike human stomachs which only produces acid when we chew. When horses secrete acid into an empty stomach, they are at risk of developing gastric ulcers.
Acid build-up in an empty horse stomach can lead to the development of gastric ulcers, diarrhea, pain-related bad behaviour and colic. Horses become anxious when left without food, whilst they release ‘happy hormones’ during grazing.
Feeding adequate roughage is also important for maintaining a healthy population of gut microbes. The symbiotic relationship between the microbiome and the horse is very important for general good health. Gut microbes not only aid digestion by producing enzymes, vitamins and nutrients that the horse needs, they also produce molecules critical for effective functioning of the immune and nervous systems.
What’s the difference between roughage, forage and fibre?
The words roughage and forage are used interchangeably to describe the grasses and plants that horses graze in fresh or preserved forms. This includes fresh pasture, hay, chaff, chaff cubes, haylage, baleage and silage.
Fibre is the structural components of plant cells, made of cellulose, hemicellulose, pectin and lignin. The cells in the young, leafy part of a grass plant have relatively thin cell walls but, as the plant ages, it adds strength to the cell walls in the stem to make it strong enough to act as the plant’s skeleton.
Flowering grass plants produce strong stems to carry their flowers, so the fibre content is higher in flowering and seeded plants than in young, leafy plants. Straw is high in lignin to provide a lot of strength to the stem.
Horses cannot digest cellulose, hemicellulose and pectin in the foregut (stomach and small intestine) because they cannot produce the enzymes needed to break down these very tough fibre components. Instead, they rely on the beneficial microorganisms in the hindgut (mainly the cecum) that are able to break fibre down into volatile fatty acids available for the horse to digest. Lignin is so tough that even gut microbes cannot ferment it.
Choosing a roughage source for your horse
Roughage usually contains at least 18% fibre, most of which is indigestible to the horse without the aid of the gut microbiome. The most common forms of roughage fed to horses in Australia are pasture, hay or chaff.
Don’t confuse ‘super fibre’ feeds, such as soy hulls and beet pulp, with roughage. Super fibres contain digestible fibre, which the horse itself is able to digest, making them healthy, ‘cool fuel’ alternatives to grain hard feeds, but are not a forage replacer.
When grass is in short-supply, free choice grass hay is the best replacement for fresh pasture unless your horse is on a weight loss or low sugar diet. The addition of a kilogram or two of lucerne or cereal hay at mealtimes provides a wider variety of amino acids in the diet. Limit lucerne or clover hay to under one-third of total forage intake because of their very high protein content.
Ideally, provide more hay than chaff because the long stems encourage more chewing, which creates more saliva to buffer stomach acid. Feeding a variety of fibre types and forms is good for the gut’s microbial diversity.
These guidelines need to be modifed if you are feeding an insulin resistant or laminitic horse or pony. These need a low starch, low sugar hay and may benefit from a small amount of lucerne or quality protein to aid recovery. Limit total intake to 1.5% of bodyweight for weight loss.
Hay can be fed in multiple piles around the paddock to stimulate more natural grazing (preferably on a mat to prevent sand ingestion), in large round bales offered free choice or in slow feeder haynets to help make the hay last between feed times. The key is to make sure that your horse is NEVER left for more than a few hours without something to eat.
Dry matter doesn’t have to be fed dry! It’s just a measure of how much solid matter is in a feed after the water content is removed.
- Lush green grass can be 10-20% dry matter or 80-90% water. Dryer, more mature pasture can be 20–30% dry matter or 70- 80% water.
- Hay, grains and pellets are typically 90% dry matter or only 10 % water.
Because 1 kg of lush grass contains less than 200 grams of dry matter, horses need to eat more kilograms of lush pasture to obtain the same amount of nutrition as that contained in 1 kg of hay (900 grams of dry matter).
How much forage should I feed?
As a good rule of thumb, horses need to consume between 1.5% and 2.5% of their body weight in total feed per day (that’s the feed’s dry matter content, not counting the moisture present). The minimum amount of roughage fed is 1% of bodyweight.
Whenever pasture levels are low or grasses are dry and stalky, horses need to be fed hay. Horses need at least 1% of their body weight as dietary forage and the majority require closer to 2% (i.e. a 500 kg horse needs 10 – 12 kg of hay per day when grass is not available, and a 250 kg pony needs 5 – 6 kg).
During competition season or when your horse is in work, you may need to feed more calories (fed as a hard feed) to supplement the forage. If your horse loses weight despite having free choice access to plentiful, good quality (leafy) grass or meadow hay, you’ll need to add a concentrate or ‘hard’ feed.
The amount of hard feed given can and should be varied to maintain weight at the required level. Seasonal changes in grass quality and variation between the calorie content of batches of hay can mean you need to adjust the amount of hard feed given even when your horse’s work level has not changed.
A horse at rest a horse should consume 80-100% of its daily intake as roughage. Horses in light work may need 65% and those in moderate work need 55-65% of their diet in the form of roughage.
Horses undergoing intense training may only have enough capacity to consume 40-50% of their daily intake as roughage due to their high consumption of energy feeds (grains/oil).
Pregnant, lactating and growing horses may also need a protein supplement to provide the necessary levels of essential amino acids, especially lysine, methionine and threonine.
Easy-keeper horses and horses needing to lose weight should be limited to 1.5% of their bodyweight in dry matter per day. This will be mainly forage, with just a token feed to provide the essential vitamins, minerals and omega-3s needed to balance the forage to meet requirements.
How do I balance a forage-based diet?
Hay contains most of the minerals, protein and calories that were present in the pasture from which it was made. But the process of drying grass to make hay means that it loses much of the original vitamin and healthy omega-3 fatty acid content.
The vitamin levels in hay decline rapidly with storage and one year old hay has virtually no vitamins left, although it will retain the minerals it had when harvested.
Fresh grass contains around four times as much omega-3 oil as omega-6.
Omega-3 is a fragile molecule easily destroyed if exposed to heat, oxygen or light. The resilient omega-6 molecules survive the hay making process unlike their fragile omega-3 cousins.
Thus hay-reliant horses need a supplementary source of vitamins and omega-3 fats as well as the minerals and salt needed to balance the rest of the intake and optimize your horse’s health and performance. For assistance in selecting the best Equine Vit&Min balancer to suit your horse, contact us or visit our product selection tool. We recommend EVM Omega-3 PLUS or Farmalogic Omega Balancer to provide essential omega-3 fatty acids.