Grazing Systems for Horses

By Ann Swinker, PhD, Extension Horse Specialist,  Penn State University

Pasturing horses and other livestock is the most economical and easiest way to feed.  Owners have several options for grazing horses. Some grazing strategies are better at maintaining pasture ground cover and reducing the risk of overgrazing than others. Remember in the Eastern U S, any grazing strategy and turning horses out on pasture should not start until the grass has reached a height of 6 inches, and should be stopped when grass has been grazed down to 2 to 3 inches. Here are some grazing strategies to choose from, pick one that best matches you management system for your operation:

• Continuous (24hrs/7day a week) grazing
• Limiting turnout time
• Rotational grazing
• Partial-season grazing
• Combination of the each

Continuous Grazing - When horses have access to pasture 24 hours a day, 7 days a week, for the whole grazing season (or even 365 days/year), they are being managed under a continuous grazing system. Unfortunately, this grazing strategy often results in overgrazing, particularly on our eastern smaller farms.

The bad thing about this system, it allows horses to be very selective. Horses repeatedly graze the best-tasting plants. This stresses plants beyond their ability to survive. Pasture is never allowed to recover from grazing. In time pastures are soon turned into dry lots where only weeds will grow.

Limiting Turnout - This strategy allowing the horse daily access to pasture for shorter periods (1-hour to 12-hours per day) is referred to as Limiting Turnout. This grazing strategy is ideal for horse boarding stables or small properties. This system gives every horse some grazing time and is ideal for horse with laminitis or other disorders related to grazing.

Turning horses out on a pasture provides exercise, but adds significant savings in feed costs over time, even if horses are turned out for a few hours per day. This system works well for people that work 9 am to 5 pm.

Rotational grazing- With this grazing strategy, horses are allowed to graze one pasture cell at a time. When forage has been grazed down, horses can be rotated into the next cell. The previously grazed cell is then allowed to recover generally it takes about 20-30 days. Or sufficient re-growth 6 – 8 inches, and them horses can be returned to that (first) pasture to graze.

The size and number of small pasture cells can vary based on available acreage, the number of horses, the productivity of the pasture, and how long the horses graze each cell. Ideally, each pasture cell should contain enough grass to sustain the horses for 3 to 7 days. Grazing for longer than 7 days may increase damage due to hoof impaction, mainly near high traffic areas. Horse owners using rotational grazing need to make sure you have enough land to lay out the grazing cells. You also need electric fence and a lot of it --to divide the pasture land into cells.  After the horses are placed in this system, remember to check the grass every day and if needed, move the horses to the next pasture before overgrazing and trampling of the grass. You have to monitor the grazing progress and remove horses to another cell or take them off the pasture and into a holding lot or paddock if you run out of grass (feed hay).

Pasture divided into (1 – 2 acre) pastures cells can make effective rotational system. Remember horses need more space than cattle or other livestock for social interactions.  Rotational grazing is not the best idea for yearling or young foal.  They tend to run into the fence and for this system to work most people use temporary electric fence that must be kept HOT.

How to Calculating Stocking Rates for Horses
Most riding horses weighing 1,000 pounds consume 600 pounds of dry matter forage each month.  A pasture planted with orchard grass and some clover will produce 3 to 8 ton/acre/yr of forage, depending on rain fall, soil type and species of plants fertilization and management.  All of these factors can increase pastures production yields.  Most horses require somewhere between 1 to 2 acres of pasture land a year to supply all the forage it need to keep the horse and the pasture plants healthy. 

Pastures that receive adequate rainfall (Pennsylvania) will grow more forage than dry land pasture.  Therefore, less acreage is needed to meet the grazing needs of the horse.  However, only a portion of the total yield produced will be eaten by the horse.  Grass that is trampled and defecated on will not be consumed. Also, a certain amount of grass residue must be left to maintain good quality re-growth.  This portion varies but averages about 30% of the pastures.  Remember, with year round turnout--- you must supplement with hay during periods of snow cover or when feed is not available.  Continuous grazing of pastures of limited acreage may require a recovery period of no grazing to maintain forage health and vigor.

In the western part of the United State or during severe period of drought, calculating the stocking rates, using the 1,000 pound horse will require 600 lbs of forage per month.  This will calculate to 7200 lbs of available forage per year (600 lbs/mo x 12 mo.).  Figuring 500 lbs of forage production per acre and using the take half, leave half principal, it will require 28.8 acres of pasture (out west) to meet the needs of the horse.  Depending on the productivity of the pasture land, supplemental feeding may be required.

Limit grazing (several hours per day) combined with supplemental feeding on smaller acreage will extend the length of the grazing seasons.  Horses will need to be housed in a box stall or a dry lot for the period of time they are not on pasture. 

What Grass Species to Plant
Not all forage species have the same growth patterns, production levels, or produce well in all soils.  Grasses alone require more nitrogen to maximize yields than a grass/legume species mixture.  Grasses will out produce a grass/legume mix over all but a grass/legume mix will out produce a grass stand in the summer months.  Species selection for soils, goals, and management are crucial. 

You must manage your pasture as a crop.  Each year fertilize according to the recommendation of a soil test.  Drag manure, clip weeds and monitor the pasture for over and under-grazing.  Contact your county Extension Office for information on soil testing and management.