UW Extension: Considerations for grazing horses

By: Makayla Getz

In the state of Wyoming, one of the most common small-acreage large animals purchased is a horse. 

The average lifespan of a horse is 25 to 30 years, so how are these four-legged herbivores living out their days for up to 30 years or even 15 years if they are only moved to a ranchette for half of their lifetime? 

Most likely eating. 

The following is some general guidance on how to get started on caring for a four-legged friend. Remember, when in doubt, always call a veterinarian.

Healthy versus

unhealthy pasture

For this article’s purpose, a healthy pasture is one thickly vegetated with desired plants and has vigorous growth during the growing season. Since this article focuses specifically on horses, desired plants are typically grasses.

A healthy native range pasture is going to look different than a healthy cultivated pasture, especially if it has consistent irrigation. However, they can both be considered healthy pastures.

Native range pastures tend to have many plants, but the vegetation height is usually not as tall or uniform as cultivated pastures. Cultivated pastures tend to be the opposite, with lower diversity of plants and rather tall uniform grass, which tends to look like hayfields. 

Both pastures can be equally healthy, with the most productive pasture being the one with the most water availability.

In addition to knowing what a healthy pasture looks like and what a horse owner wants their pastures to be, they also need to be able to identify unhealthy pastures. 

Unhealthy pastures have a lot of visible soil due to little or no vegetation, typically have an abundance of weeds and can have tall standing vegetation not desirable for grazing. 

Many times, unhealthy pastures are overgrazed and therefore look like a drylot with only soil or dirt – no native or added vegetation. In severe situations, the ground is so degraded if weeds grow on the property, it is considered an improvement.

How forages grow

Grass stems are generally hollow, supporting the plant and directing its leaves toward the sun. These stems also contain vessels like phloem and xylem, which transport water, nutrients and sugars throughout the plant. 

Additionally, leaves generate energy for the plant’s growth while also exchanging carbon dioxide, oxygen and water vapor with the atmosphere. The chlorophyll in the leaves enables photosynthesis, where sunlight is captured and transformed into the chemical energy in glucose – sugar.

Some perennial grasses can reproduce and spread from modified roots called rhizomes or stems called stolons. 

Rhizomes are modified roots which grow horizontally below ground and spread away from the parent plant, then rise to the soil surface to form a new shoot and plant which is an identical clone from the parent plant. These types of grasses are identified as rhizomatous grasses, which tend to form a sod of grass like a Kentucky bluegrass lawn. 

Stolons are modified stems which grow horizontally along the ground away from the parent plant and then form roots and new shoots at various nodes giving rise to identical clones of the parent plant. An example would be buffalo grass, which is a native species to Wyoming.

Nutritional quality and palatability of grasses decrease as they progress towards maturity. New growth is always the more digestible and palatable to horses because it is the most tender and softest tissue. 

During this phase, the lignin content of the plant is the lowest because the amount of stem is the lowest with a great amount of leaves, which contain a lot of protein. 

As the grass progresses towards maturity, lignin increases and leaf growth slows, shifting to more stem growth. The shift in stem-to-leaf ratio and the increase in lignin is why palatability and nutrition decreases.

Once the grass reaches the reproductive stage, grasses are less palatable because of the old leaf material and stemmy nature of the reproductive structures. 

A point to note is yield – or biomass created – has an indirect relationship to nutritional quality. Therefore, nutritional quality of grass is at its highest with earliest new growth, however yield is at its lowest. 

The highest nutritional quality and highest yield intersect during the boot phase. The reproductive phase has the highest yield production, while the maturity phase loses yield slightly but has the lowest nutritional quality in all of the growth phases.

This is why horses select different forages throughout the year and why forages can have a huge impact to a horse’s nutritional needs, which directly impacts their overall health. 

It is important to know not all grasses develop at the same time or rate. There are nutritional differences between grass species, and cool-season grasses are often in the reproductive phase when warm-season grasses are beginning to grow. 

This is why one can see horses selecting different forages in pastures, why some grasses are never eaten and native pastures have a longer season of green vegetation – the shift between cool-season and warm-season grasses.

In the end, the overall goal is to maximize yield – tons per acre – of grasses produced in pastures for the health and well-being of horses. 

The amount of biomass created by grass is impacted by environmental factors with the two most important factors being temperature and moisture. 

Yield decreases if temperatures do not stay within optimal growing conditions and when soil moisture is not maintained within adequate levels – too low or in excess.

Purchasing grass seed

By now, readers are probably asking, “Where do I buy this grass seed and what type do I get?” 

Many seed mixtures can be purchased locally at agriculture supply stores, such as Bomgaars, Murdochs, Tractor Supply, local co-op stores, agriculture supply companies, etc.

Another source could be a local Weed and Pest office.

These companies typically sell seed in mixes for irrigated or non-irrigated pastures and are already bagged for sale. This is easy and convenient for the buyer. However, the buyer does not have a selection of which forage species or ratio of the species are in the bag. 

These mixtures are created from grass species which germinate well, tend to grow in a variety of conditions and can establish great pastures.

Individuals who want specific grass species or grass mixes can source seed from a seed company. 

There are numerous seed companies around the region. These seed companies specialize in selling seed and usually have a wide selection of native and non-native species. They sell seed in preestablished seed mixes, custom mixes or individual seed lots.

Species can also be selected for haying or grazing capabilities. 

Again, all grass species can be grazed. However, the grasses with more upright and vertical growth with minimal basal leaves are best for hay production and can also be grazed. Grasses with a lot of basal leaves, which are leaves growing from the ground, are not good for haying, but are great for grazing.

To choose the highest-quality seed, select seed with a high percentage of pure seed – 80 percent or more – the lowest percentage of other crop seeds, inert matter and weed seeds and the highest percentage of germination. 

If possible, purchase seed produced in Wyoming because those are species that grow well in this state, and this helps supports local agricultural producers.

This article is a continuation of a previously published Wyoming Livestock Roundup article from July 19, which can be found at wylr.net/2024/07/19/theres-a-horse-in-my-yard-now-what/.

Makayla Getz is the University of Wyoming Extension educator for agriculture and natural resources serving Park County. She can be reached at mgetz@uwyo.edu or 307-527-8568.