To Mow or Not to Mow...?
Caring for Your Horse Pasture
By Dr. Stephen Duren
“Mowing” is a term used to describe the cutting or trimming of grass. The mowing process cuts grass to a uniform height in a pasture or lawn. If your pasture management plan doesn’t include mowing, you may be asking the following questions:
- Do the pastures, paddocks, or fields used to graze horses require mowing?
- At what height do you mow pasture grass?
- Are there any risks associated with grazing horses on freshly mowed pasture?
- Are there any potential benefits of mowing?
Benefits of Mowing
The main goal in pasture management is to maintain or to enhance grass quality. The intake of pasture grass can be a significant source of nutrition for the grazing horse if the pasture is properly managed. Mowing is one of the tools for better pasture management. Some horse owners mistakenly feel that mowing pastures is done simply to make the pastures look nice. However, there are several valid reasons to consider mowing pastures. Some potential benefits of mowing include weed management, enhancing forage quality, and reducing grazing patterns.
Pity the horse that has to find something to eat in this poorly maintained pasture. This pasture is full of weeds, with very little forage of nutritional value and well established grazing patterns creating many ungrazed areas with weeds that have gone to seed.
Mowing pastures is a great means of controlling weeds. Repeated mowing of pasture decreases the competitive ability of a weed to survive in a grass paddock. Keeping weeds the same height of grass will give grass an advantage, and prevent weeds from shading and restricting grass growth. Mowing also serves to prevent weeds from establishing seed heads. Eliminating seed heads prevents weeds from reproducing and spreading in the pasture. The control of weeds in a pasture does not occur with a single mowing, but is facilitated with repeated mowing.
Mowing pastures enhances pasture quality. A grass plant that is actively growing is constantly producing nutrients that horses can utilize. The mowing process keeps grass plants in a vegetative or growing state. Mowing prevents the plants from reaching a reproductive state when they develop a seed head and ultimately cease growing. Mowing also keeps plants at a shortened height which increases digestibility and palatability. As grass plants grow tall they become fibrous and less digestible. When mowing grass pastures, it is important not to cut grass plants too short since cutting too short will reduce leaf area which is needed to stimulate growth. A grass plant that is cut too short is also prone to stress and may die. The optimum height for a cool-season grass is approximately four inches (10 cm), while the optimum height for a warm-season grass is approximately eight inches (20 cm).
Mowing pastures also reduces grazing patterns. Horses tend to graze in certain areas of a pasture and utilize other areas of the pastures to pass manure. The grazed areas are very short and known as “lawns.” The ungrazed areas consist of taller grass and they are known as “ruffs.” This is a bit of golf course terminology, but it describes well the different areas of a horse pasture. Mowing serves to shorten the taller grass and enhance its palatability. Over time this will help to eliminate the grazing patterns that can exist in horse pastures and provide better utilization of pasture.
What are the risks, if any, for horses grazing mowed pasture?
The biggest risk associated with mowed pasture is the possibility that the horse may consume molded grass. Once grass is mowed, the portion of grass that is clipped from the plant contains a high moisture content. These clippings are prone to molding. If horses eat grass that has molded, it can cause a variety of symptoms including coughing and nasal discharge, and extreme instances result in death due to mold toxins.
Another potential risk of clipped forage is choking. If horses take in large mouthfuls of short grass clippings they can potentially choke. Both the risk for ingestion of mold and for choking can be virtually eliminated if the pasture is harrowed following mowing. The harrowing process spreads the grass clippings evenly throughout the field and dramatically decreases the likelihood of any problems.
This article was originally published in the July 2015 issue of Canadian Horse Journal.
Main article photo: Mary R Vogt