Growing and producing horse-quality hay can be both a rewarding and frustrating experience. On one hand, horse owners are often willing to pay a premium for what they consider “horse-quality” hay, but on the contrary, they can be much more selective as compared to other clientele. It is important to understand the needs of the horse industry when producing hay for this market. The horse industry is diverse, which makes their needs difficult to pinpoint. Age, production status, workload and overall health of horses greatly influence their requirements, particularly in regard to their forage needs. Because of the diversity of clients in the horse industry, there are many opportunities for hay producers to find a niche and serve some part of this community.
Before discussing the hay needs of horses, it is important to understand how the horse’s gastrointestinal tract is unique from our other hay-eating farm animals. The horse is considered a monogastric animal, meaning that it has a single stomach. Food moves fairly rapidly through the stomach into the small intestines, where the horse’s enzymes digest and absorb much of the food that it eats. The food that is left undigested after the small intestine is typically the fibrous component, which then moves to the hindgut of the horse. Bacteria in the hindgut break down the fiber that the horse cannot digest on its own and in the process release volatile fatty acids (VFAs) that the horse uses for energy. The hindgut of the horse is larger and more developed as compared to other monogastric animals (e.g., pigs, humans, etc.) which allows the horse to better digest and utilize fiber as compared to other monogastric species.
However, the hindgut fermentation process is not as efficient when compared to ruminant animals (cows, goats, sheep, for example) where fiber is digested for a longer period of time in the foregut of the animal. For this reason, horses are typically thought to need a higher-quality forage with more digestible fiber as compared to ruminant animals.
Quality feed
What makes the forage higher quality? This is primarily determined by maturity of the plant at harvest as well as harvest practices. While it can be tempting to cut hay on longer intervals to increase the yield of each cutting, it is a better practice to cut hay at an earlier stage of maturity. While the yield per cutting may not be as great, more cuttings can be made per growing season, and the hay will be higher quality. As plants mature, the fiber becomes more lignified and less digestible to the horse.
If we were to analyze hay via a forage report, what we see is an increase in acid detergent fiber (ADF) and neutral detergent fiber (NDF) as the plant matures. As these fiber measures increase, the digestibility of the forage decreases, and the horse’s intake of the forage (willingness to eat it) also decreases. (If a horse refuses to eat your hay, the owners are much less likely to buy it again!) Guidelines for upper thresholds for ADF and NDF vary slightly and are somewhat arbitrary, but are generally referenced at approximately 45% ADF and 65% NDF. Hay above this is typically labeled as unsuitable for horses, and lower values for these measures would make hay more desirable for those horse owners seeking high-quality hay.
Once hay reaches the growth stage of producing seedheads, it is typically more mature than what is desired for horses. As fiber becomes less digestible to the horse, it is also more likely to cause gastrointestinal issues such as colic and diarrhea in part due to disruption of the fiber-digesting microbes in the hindgut. (If a horse colics or develops diarrhea on your hay, the horse owner is not likely to buy it again!)
Cutting approach
In addition to the stage of maturity at harvest, there are other harvesting practices that affect the quality of hay produced. A recent study in our lab investigated fiber content of bermudagrass hay over a two-year period. Bermudagrass typically has a high NDF level (greater than 65%) which frequently leads to it being cautioned against in the horse industry. In our research, we harvested bermudagrass at different intervals ranging from four to eight weeks. Growth rate of the plant obviously varied based on temperature, rainfall, etc., so an ideal cutting interval will vary based on these external factors.
However, we noticed that approximately half of our samples fell below the 65% NDF threshold, which was somewhat surprising given that the majority of bermudagrass forage reports that are sent to me for interpretation are above 65% NDF. Upon reflection of potential differences that may have accounted for this higher quality in our samples, we believe it is likely due to differences in cutting heights. Mower height in our research was set to an approximate 5-inch cutting height. Cutting at a higher location on the plant results in better-quality forage due to an increased leaf-to-stem ratio. The stems of plants are much more fibrous and less digestible to the animal as compared to the leaf, and the base of the stem is particularly lignified and indigestible. Therefore, raising cutting height of the mower should result in a higher-quality forage. It also should allow for faster regrowth of the plant by allowing the plant to retain more aboveground material for photosynthesis. For many species of forage, this also helps prevent root dieback and allows stands to persist longer.
How much quality?
It is important to recognize that not all horses need the highest-quality hay. While growing, lactating and performance horses all have high energy demands that need to be met with high-quality forage, many horses in today’s society are idle. Obesity and obesity-related health issues such as insulin dysregulation and insulin-mediated laminitis are problems that many horse owners are grappling with today. For this reason, there is an increased demand for hays that are low in nonstructural carbohydrates (NSC). NSC refers to the sugars and starches in the plant that are enzymatically digested in the small intestine of the horse and result in higher blood glucose and insulin levels. Because higher blood insulin levels may trigger laminitis in affected horses, owners of these horses frequently seek hay that has low NSC levels (10% is the targeted NSC level for obese horses with metabolic issues).
Because these horses may still be adversely affected by overly mature hays with high NDF, ADF and lignin levels, horse owners are faced with a dilemma of finding hay with fiber that isn’t too indigestible in order to prevent gastrointestinal upset, but that also has a low NSC level and a somewhat lower calorie level to manage obesity and blood insulin levels. In my experience, horse owners in this predicament most commonly select either a high-quality warm-season grass hay such as bermudagrass (bermudagrass typically has a low NSC but must be cut properly to achieve reasonable NDF levels) or a somewhat lower-quality timothy or orchardgrass hay. (These typically fall within recommended ADF and NDF levels but are higher in NSC – however, many harvest practices can affect the NSC levels.) Alfalfa, though low in NSC, is typically highly digestible and provides too many calories for obese horses.
As you can see, providing appropriate hay for horses can be a complex and multifactored issue. Forage is an extremely important component of the equine diet, as it should make up the majority of what the horse consumes. Hay producers are a valued part of the equine industry and contribute greatly to the health of the horse. Hay producers seeking to get involved in the equine industry can consult (at no charge) their local county extension agent who can put them in touch with an equine nutritionist to help answer more specific questions regarding the production of hay for horses.
