History and Contemporary Uses
The role of horses in society has changed significantly in the last century. Their uses for farm work, carriage, under saddle, and as the ‘engines’ for delivery and fire-fighting vehicles, are parts of a by-gone era. In 1925, there were more than 19,000,000 horses in the U.S. (USDA, 1925) and their numbers for various uses were compiled and reported along with cars, tractors and other vehicles.
Today some horses and mules are used for work under saddle with a smaller number of horses and mules used as draft animals, but most are ridden for pleasure or sport.
This USDA APHIS (2017) tables gives us an overview of the contemporary uses of horses in the United States.
Dramatic changes have occurred in horse industries in the last 20 years as well. In this period, during which most horses are kept for sport and companionship, numbers have again declined. In 2012 the number of horses and ponies was 3,621,348 which was a decline of 4,028,827 from 2007. That decline was attributed to the great recession. 47.2% of equid operations used the animals for pleasure, 25.0 % for farm and ranch work and 1.6% were used in racing (USDA APHIS, 2017). Although horses are not purposefully raised as meat animals in the United States, approximately 1-2% are exported to Canada and Mexico to be slaughtered each year while 10-12% are euthanized (AVMA, 2012).
Contemporary statistics are less complete than those for other farm species because most horses are not sold in regulated markets and they are not a commodity. USDA statistics include farms where five or more animals are kept, and data is self-reported by farm owners. This USDA APHIS (2017) map also reveals that recent statistics include data from only 28 states.
In sharp contrast, the number of feral (wild horses) on range has increased dramatically. Controlling their numbers is needed for the protection of soil, water and vegetation resources which comprise wildlife habitat and other multiple uses as dictated by the Federal Land Policy and Management Act of 1976. However, the affinity some people feel for this charismatic species leads them to oppose population control efforts commonly used in other populations of domesticated horses.
Approximately 88,000 feral horses are managed by the BLM on 26.9 million acres of public lands. The population growth rate of this group of horses was 7.5% from 2018 to 2019 (BLM, 2019). More than 11,000 horses were removed from rangelands in that same time period with some being adopted by the public and others being housed in holding facilities. The Northwest Tribal Horse Coalition (2019) also seeks to address the challenge of horse over-population on tribal rangelands through several herd reduction practices.
Feeding of Horses
Many who manage horses choose to feed high quality hay and concentrated feeds. These practices produce demand for value-added hay. The value of hay produced and sold in Oregon in 2017 was $580,434,000. While this number includes all hay (fed to many species including dairy animals) some growers target a specialty market of horse farms. For this market, hay growers produce light bales, 60-80 lbs. each, with lower nutrient density in carbohydrates and protein as compared to dairy hay.
Managers of horses are increasingly interested in low carbohydrate hay to avoid, or cope with, problems such as laminitis and insulin resistance in horses. While there is a genetic component to these diseases, these syndromes are largely due to over-feeding of horses confined in stalls or paddocks and over-consumption of feeds in greater quality or quantity than the horses require for maintenance.
Management of Pasture for Multiple Uses
Recommendations for horse-keeping often emphasize the importance of pasture for exercise and benefits of improved dispositions (Golenz and Roser, 1996). While these are essential components of horse physical and emotional well-being, they do not help one to understand the under-lying need to manage the soil and plants in the pasture.
The season and duration of grazing affect the nutritive value of the plants for the horses and the ability of plants to re-grow after each grazing bout. Consider that, with every bite, the grazing animal reduces the ability of the plant to photosynthesize. Fortunately, grasses evolved with herbivores and selection of grass cultivars for pasture means that plants of good nutritional value and resilience to grazing and trampling have been genetically selected for.
Additionally, the effect of grazing on soil health and plant re-growth potential needs to be considered. Balancing our view of the pasture as a resource for fitness with the pasture as its own biotic community will lead to sustained pastures with little compaction and healthy plant species and cover. Creating a small sacrifice area, where the horse can exercise and roll to meet its natural behavioral needs, allows managers to protect pastures from over-grazing and the effects of trampling by horse hooves.
Nutrition from Pasture and Hay
The amount of pasture, or standing forage, available to maintain an animal is estimated using the average height of the plants in a pasture, or area, to be grazed. The dry mater (DM) available can also be estimated by cutting numerous samples, drying them and determining DM by difference. This technique is most often used in research and is not a practical as estimates using pasture sticks or other field techniques.
Water content is high, up to 80% of the fresh weight, in rapidly growing grasses and legumes. Animals on these pastures may consume a large amount of forage but may still lack essential nutrients. Mineral deficiencies or excesses, relative to grazing animal need, vary by region and are influenced by soil type, plant uptake of minerals and historic uses of a site which may have contributed to the mineral profile of the soil. The need for supplementation is most accurately determined by forage analysis conducted at a lab. Extension Service publications may direct you to your nearest resources. A useful Oregon State University publication is EM 8677, Analytical Laboratories Serving Oregon
Horse pastures should be predominately grass and not clover or other legumes. Horse pasture mixes for the Pacific Northwest commonly include orchardgrass, perennial ryegrass and Kentucky bluegrass. Timothy is also highly palatable for horses but is less tolerant of grazing pressure and trampling so it will decline in prevalence over time. Timothy hay is commonly fed to horses.
Although the demand for protein can be met with legumes, such as clover, these are not purposefully included in seed mixes for establishing new horse pasture in the Pacific Northwest because clovers will become too large a portion of the pasture over time. Under hoof action, and subsequent soil compaction, the more shallow-rooted clovers will thrive and become a dominant part of the pasture plant community.
Challenges with Feeding Legume Hay to Horses
Over-ingestion of clover can lead to bloat as the readily digestible proteins are utilized by gut microbes which produce gaseous by-products. Clover hay is fed in some parts of the U.S., but care must be taken to avoid molds which are common in these plants. If ingested, they can induce toxicoses in horses and other livestock species.
Obesity is one of the most common diet-related problems in horses. It can be avoided with proper diet and exercise. The lack of owner knowledge about ideal body condition scores (BCS) contributes to this problem and has similar causes and consequences as human obesity (Johnson et al., 2009). Obese horses suffer from reduced exercise tolerance, insulin resistance and laminitis.
Hay with more than 10% carbohydrate is not recommended for obese animals (Lenz, 2019). Horses which consume a diet rich in carbohydrate, without the appropriate level of exercise, can develop laminitis (inflammation of laminae within the hoof) which is painful and debilitating. This can be caused by grazing too much early stage grass on a pasture which is experiencing fast re-growth. This can occur in any season when soil moisture in adequate and hours of sunlight allow for increased plant growth. In the Pacific Northwest, this is common in Spring as hours of daylight increase allowing for fast vegetative growth or in Fall and early winter when soils are moist and sunny days increase soil temperature and stimulate re-growth of established grasses. Managers must adjust the hours of grazing to match the nutritive value of the pasture sward and the nutrients fed as hay or other supplements.
Over-feeding, from any source, can result in metabolic challenges and illness. Carter et al. (2009) observed that horses, in an experimental trial, fed two times their dietary requirement gained weight and concurrently developed decreased sensitivity to insulin. In clinical practice, veterinarians refer to this syndrome as insulin resistance (IR). While genetic factors have an influence, prevention of the problem with exercise and an appropriate diet is the most effective approach.
Some nutritionists advocate choosing low carbohydrate hay as preventative to the development of laminitis. Teff grass, a native of East Africa, has become increasingly popular (Shaw, 2018) but this requires water availability during the warm (summer) season. Water supply is limited in the Pacific Northwest, and irrigated horse pasture is not practical for most farms. Irrigation also allows intestinal parasites to persist on pastures and, if over-grazed to a height less than 4 inches, the likelihood of fecal-oral parasite transmission increases.
Horse-related guides for 4Hers and others
University of Kentucky
Choosing Hay for Horses
Using Soil-Cement on Horse and Livestock Farms
Paddock Paradise for Horses
Texas A&M University
Selection and Use of Hay and Processed Roughage in Horse Feeding
Gluck Equine Research Center Faculty Publications, University of Kentucky
Andrews, S., D. Walenta, C. Sullivan, L. Henderson, and L. Brewer. 2017. Analytical Laboratories Serving Oregon. https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/em8677.pdf
AVMA. 2012. Unwanted horses and horse slaughter FAQ. https://www.avma.org/KB/Resources/FAQs/Pages/Frequently-asked-questions-about-unwanted-horses-and-horse-slaughter.aspx#HorseSlaughterTransport (Accessed 5 September 2019.)
BLM. 2019. Wild horse and burro on-range population estimates. https://www.blm.gov/programs/wild-horse-and-burro/about-the-program/program-data (Accessed 5 September 2019.)
Carter, R.S., L. J. McCutcheon, L. A. George, T. L. Smith, N. Frank, and R.J. Geor. 2009. Effects of diet-induced weight gain on insulin sensitivity and plasma hormone and lipid concentrations in horses. American Journal of Veterinary Research 70 (10): 1250-1258.
Golenz, R.M. and J.F. Roser. 1996. Equine Husbandry. in: Book of Horses: A Complete Medical Reference Guide for Horses and Foals, Siegal, M. (ed.), Harper Collins Publishers, New York.
Johnson, P.J., C.E. Wiedmeyer and V. K. Ganjam. 2009. Medical implications of obesity in horses- Lessons for human obesity. Journal of Diabetes Science and Technology 3(1):163-174.
Lenz, T. 2019. Equine Obesity. American Association of Equine Practitioners. https://aaep.org/horsehealth/obesity (Accessed 5 September 2019.)
Northwest Tribal Horse Coalition. 2019. Managing excess feral horses in the inland northwest. https://www.ynwildlife.org/Wildhorsecoalition.php (Accessed 5 September 2019.)
Shaw, N. 2018. The growing demand for low-carb horse hay. Progressive Forage. March issue. https://www.progressiveforage.com/forage-production/harvest-and-storage/the-growing-demand-for-low-carb-horse-hay
USDA APHIS. 2017. Equine 2015: Changes in the U.S. Equine Industry, 1998-2015. https://www.aphis.usda.gov/animal_health/nahms/equine/downloads/equine15/Eq2015_Rept2.pdf
USDA. 1925. Horses, Mules, and Motor Vehicles. USDA Statistical Bulletin No. 5. Government Printing Office, Washington. https://downloads.usda.library.cornell.edu/usda-esmis/files/qv33rw655/db78tg38w/5d86p3338/horsemulemvstat_Horses__Mules__and_Motor_Vehicles__1840-1924.pdf