A forage-based diet is the best way to support your horse’s health and happiness, but it is not always easy to know how much hay to feed.
Horses that are allowed free-choice (ad libitum) access to hay-only diets will typically consume 1.5 – 3% of their body weight in forage on a dry matter basis.  For a typical adult horse, this is roughly 4 to 8 flakes of hay per day.
Feeding too little hay increases the risk of gut health issues such as gastric ulcers and hindgut dysfunction.  Stereotypical behaviour such as cribbing and weaving are also more prevalent in horses fed forage-restricted diets. 
But over-feeding hay or providing hay that is too energy dense for your horse’s needs can lead to weight gain and increased risk of equine metabolic syndrome and laminitis.
For overweight horses, forage restriction is sometimes required to support weight loss and metabolic health. An equine nutritionist can help you determine how much hay to feed your horse and provide management guidance.
The best way to determine how much hay you should feed your horse is to submit a sample for analysis. Knowing the energy content and nutritional profile of your hay will ensure you provide the right amount for your horse’s individual needs.
Importance of Feeding Hay
Horses naturally evolved to spend 50 – 60% of their time grazing on high-fibre roughage including grasses, legumes, and other plant material. 
Compared to other mammals, horses have relatively small stomachs and should be fed many small meals throughout the day and night. Wild horses consume forage continuously, leaving little time spent with an empty stomach. 
Ensure your horse does not go long periods without access to forage. Providing free-choice forage at all times is the best way to mimic your horse’s natural time budget and grazing pattern.
Restricted Hay Access
Modern management practices can interfere with natural feeding behaviours. Horses may have limited forage access and instead be fed 2-3 meals of high-energy concentrate feeds.
This shift towards lower fibre intake and higher sugar and starch intake can negatively affect health and behaviour.
- Gastric ulcers
- Hindgut acidosis
- Equine metabolic syndrome
- Insulin resistance
- “Hot” behaviour
If your horse needs less energy in their diet, avoid restricting hay and instead find ways to reduce calorie consumption by slowing down their intake and choosing lower-quality forage.
Using a slow feeder or hay net, dispersing hay around your horse’s paddock or stall, soaking your forage, or replacing some hay with straw can decrease energy intake.
A typical 500 kg (1100 lb horse) should consume 7.5 – 15 kg (16.5 – 33 lb) of forage daily or 4 to 8 hay flakes.
Maximizing forage intake and reducing reliance on grain-based complete feeds can support your horse’s overall health and well-being.
For most maintenance horses, hay provides sufficient energy and protein to meet dietary needs. High-performance horses, lactating mares, and growing foals may require additional energy and protein, which can be provided as beet pulp, fat supplements, hay cubes, or soybean meal.
Horses on a forage-only diet do require supplemental vitamins and minerals because hay alone will not meet nutrient requirements.
Choose a concentrated vitamin and mineral supplement, such as Mad Barn’s Omneity, which does not contain any fillers or added sugars.
5 Key Factors when Feeding Hay
Many factors affect how much hay you should feed your horse including hay quality, the horse’s body condition, breeding status, activity level, and local climate.
Most horses will consume roughly 2% of their body weight in dry matter per day.  For a 500 kg (1100 lb) horse, this is 10 kg (22 lb) of forage per day.
Hay provision should also take into consideration management conditions, other feeds being provided, health concerns, the presence of any stereotypical behaviours, and dental issues.
Work with an equine nutritionist and veterinarian to design a balanced feeding program for your horse and remember these 5 key factors for feeding hay.
1) Body Condition Score
The Body Condition Score (BCS) is a tool to assess your horse’s energy balance by evaluating fat deposits on their body.
The Henneke scale is the most used system and scores horses from 1 (Emaciated) to 9 (Very Obese). 
Monitor your horse’s body condition regularly to determine how well their diet meets their calorie needs and whether adjustments need to be made.
- Scores 1 – 3: Diet does not provide enough energy.
- Scores 4 – 6: Diet provides energy near the requirement.
- Scores 7 – 9: Diet provides too much energy.
If your horse is underweight (BCS 1 – 3), increase the energy supply of their diet to improve their condition. This should be done carefully under the guidance of an equine nutritionist and veterinarian.
To support weight gain, provide ample access to high-quality palatable forages such as immature alfalfa.
For horses that are overweight (BCS 7 – 9), decrease the energy supply of the diet by removing additional calorie sources such as complete feeds and grains.
In some cases, restricting forage access to 1.5% of body weight may be required to promote weight loss.
Do not reduce forage below this amount unless under the guidance of a veterinarian.
2) Hay Maturity & Quality
The nutritional quality and palatability of hay can influence how much the horse is willing to consume. These factors depend largely on the stage of maturity of the plant when it is cut to make hay.
Although visual assessment can give you some idea of maturity and nutritional profile, a hay analysis is the only way to know the protein, fibre, and energy content of your hay.
As the legume or grass matures, the nutritional profile changes in the following ways:
- Decreased protein content
- Decreased digestible energy
- Increased fibre content
- Lower NSC (sugar + starch) content
Mature hay will have a higher percentage of stems than leaves or blades. This results in higher overall fibre and lower protein content.
In general, higher fibre (neutral detergent fibre or NDF) levels in mature hay correlate with a lower voluntary intake of hay. Hay with NDF greater than 65% has lower palatability and digestibility. 
Mature hay is appropriate for horses at maintenance and light work because free-choice access will allow natural feeding behaviour without oversupplying energy.
Horses with higher energy requirements (i.e., growing, heavily exercising, lactating) should be fed high-quality hay that was cut at earlier growth stages to provide higher energy and protein content.
3) Management Practices
Management practices should try to mimic this natural feeding behaviour. The goal is to ensure the horse has constant access to forage and never goes longer than 4 hours without eating. 
Several strategies can be used to extend meal time:
- Slow feeding devices (such as hay nets) 
- Provide free-choice access to less nutritious hay to allow for maximal hay intake without oversupplying energy
Pasture availability and quality also impact how much hay you should feed. Pasture can replace some or all hay inclusion in the diet if it is of sufficient quality and availability (grass is dense and 6-8 inches tall). 
A horse on a dry lot or an overgrazed field will require hay to make up the base of their diet and supplement their grazing time.
If the horse cannot safely handle long fiber without risk of choke, hay cubes or pellets should be fed to replace hay.  These should be split into multiple feedings to provide the horse with foraging time throughout the day.
5) Cold Weather
Healthy, mature horses can maintain their body condition without being blanketed during the cold weather but will require more hay than the blanketed horse. A mature horse may eat up to 3% of its body weight in hay (on a dry matter basis) in the winter. 
Studies report that unblanketed horses consume an additional 0.2% of their body weight in hay (on a dry matter basis) compared to unblanketed horses. 
A 500 kg horse consuming 10 kg dry matter during warm weather might consume 11 kg in cold weather. Although this may seem marginal, it represents roughly 7 flakes of hay per day compared to 6 flakes in the summer.
Providing free choice hay during the winter is ideal for horses who are not overweight. Additional hay is necessary for all horses at temperatures below their LCT.
Measuring Hay for your Horses
Most horse owners determine how much forage to feed their horses by counting flakes of hay. Square hay bales are usually divided into 12 to 16 flakes.
The typical two-string small square bale of grass hay weighs between 27 – 32 kg (60 – 70 lb), but larger three-wire bales can weigh between 45 – 57 kg (100 – 125 lb).
A single flake of hay usually weighs between 1.7 – 2.7 kg (4 – 6 lb) and horses are usually fed 4 – 8 flakes of hay per day.
However, there can be significant variation in weight between different flakes and hay bales. Weight may be affected by forage type, moisture content, flake size and baling technique.
How to Weigh Your Forage
For this reason, it’s important to weigh your horse’s hay to ensure they receive the appropriate amount of energy from forage.
This can be done using a hanging scale and following these steps:
- Use a bucket or empty hay net to hold the hay (or hay cubes)
- Hang the empty bucket or hay net and zero the scale
- Fill the bucket or hay net with the amount of hay you currently feed your horse
- Weigh the filled bucket/hay net
- Record the weight on an as-fed basis
- Convert to dry matter basis
As Fed vs. Dry Matter
Equine nutritionists look at the nutrient profiles for different forages on a dry matter basis instead of an as-fed basis.
Dry matter measures the mass of feed after removing water content. Looking at dry matter values for feedstuffs makes it easier to compare nutrient concentrations and improves feeding precision.
The average dry matter content of hay is 85 – 90%, with a moisture content of 10 – 15% water. This value will be available on your hay analysis report.
Most horses will consume roughly 2% of their body weight in dry matter per day. For a 500 kg (1100 lb( horse this is 10 kg (22 lb) of dry matter per day.
Coverting to As-Fed
You can convert to as-fed values by dividing by the dry matter percentage of your hay. For example, to feed 10 kg of dry matter from hay with 15% moisture, you will need to weigh out 11.8 kg of hay (as-fed).
The calculation is dry matter weight divided by dry matter percentage:
10 kg / 0.85 = 11.8 kg as-fed
Coverting to Dry-Matter
Conversely, to determine the dry matter weight based on the as-fed weight, multiply the as-fed weight by the dry matter percentage.
For example, if you weigh out 12 kg of hay and want to know how much dry matter you are feeding the calculation is:
12 kg x 0.85 = 10.2 kg dry matter
Because moisture content can vary between hays, feeding by weight ensures accuracy when balancing your horse’s diet.
Sample Hay Feeding Plans
Below are sample hay-feeding plans for mature ponies and horses, according to desired body condition change.
These are based on moderate-quality grass hay that contains 13% moisture, 10% crude protein and provides 2 mcal / kg digestible energy.
Table 1: Sample Forage-Based Diet for a 200 kg Pony at Maintenance
|Reduce Weight||3.5 kg
|Maintain Weight||4 kg
|Gain Weight||4.5 kg
Table 2: Sample Forage-Based Diet for a 500 kg Horse at Maintenance
|Reduce Weight||9 kg
|Maintain Weight||9.8 kg
|Gain Weight||11.5 kg
Regional climate and harvesting conditions may impact the ability to make hay. In these cases, haylage and silage (forages stored at higher moisture levels) can be used in equine diets.
Cut hay is also deficient in Vitamin E, and horses will require supplementation to maintain antioxidant status.
Supplement your horse’s forage-based diet with a concentrated vitamin/mineral supplement that meets their micronutrient needs without supplying excess energy and protein.
Mad Barn’s Omneity Premix is a comprehensive vitamin and mineral supplement formulated with 100% organic trace minerals and Vitamin E. It is designed to balance the majority of forage-only equine diets.
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