Grazing Systems for Livestock and Horses

Pasturing horses and other livestock is often the most economical and easiest way to feed. Producers have several options for grazing livestock and horses. Some grazing strategies are better at maintaining pasture ground cover and reducing the risk of overgrazing than others. Remember that in the Eastern United States, any grazing and pasture turnout should not start until the grass has reached a height of 6 inches, and should be stopped when grass has been grazed down to 3 to 4 inches. Here are some grazing strategies to choose from; pick one that best matches your management system for your operation:

• Continuous (24hrs/7day a week) grazing
• Limiting turnout time (used most often with horses)
• Rotational grazing

Continuous Grazing

When horses have access to pasture 24 hours a day, 7 days a week, for the whole grazing season, they are being managed under a continuous grazing system. Unfortunately, this grazing strategy often results in overgrazing, particularly on smaller farms.

A limitation of this system is that it allows stock to be very selective. Animals repeatedly graze the best-tasting plants. This stresses plants beyond their ability to survive. Pasture is never allowed to recover from grazing. Over time, pastures are turned into dry lots where only weeds will grow.

Limiting Turnout

This strategy (allowing daily access to pasture for shorter periods of 1 to 12 hours per day) is referred to as limiting turnout. This grazing strategy is ideal for horse boarding stables or small properties because multiple groups of horses can be turned out on the same fields. This system gives every horse some grazing time and could be ideal for horses with laminitis or other disorders related to grazing (consult with your veterinarian to confirm - sometimes these horses should not graze at all). The time of day when forages are lowest in non-structural carbohydrates (sugars, starch, fructans) is generally very early morning. However, after cold nights, non-structural carbohydrates may remain high in the morning and rise higher during daylight hours.  

Turning horses out on a pasture provides exercise, but can also add significant savings in feed costs over time, even if horses are turned out for a few hours per day. However, this is still a form of continuous grazing because each pasture is used daily, and pastures may still deteriorate over time. 

Rotational grazing

With this grazing strategy, stock are allowed to graze one pasture cell at a time. When forage has been grazed down, animals can be rotated into the next cell. The previously grazed cell is then allowed to recover; it generally takes about 20-30 days for the forage to regrow to 6-8 inches in height. Once forage has recovered, horses can be returned to that pasture to graze.

The size and number of small pasture cells can vary based on available acreage, the number of animals, the productivity of the pasture, and how long the horses graze each cell. Ideally, each pasture cell should contain enough grass to sustain stock for 3 to 7 days. Grazing for longer than 7 days may increase damage and pasture recovery time due to horses grazing forage regrowth, which begins after about 7 days, and soil compaction, mainly near high traffic areas. Producers using rotational grazing need to make sure they have enough land to lay out the grazing cells. You also need electric fence to subdivide the pasture land into cells. After the animals are placed in this system, remember to check the grass every day and if needed, move the animals to the next pasture before overgrazing begins. You have to monitor the grazing progress and rotate animals to another cell or confine them to a holding lot or paddock if you run out of pastures with 6-8 inches of forage available.

Pasture cells can range in size depending on how much land is available and how much room the animals need.  Rotational grazing is a good way to make efficient use of a small property and still get good forage yields. If animals get along, cells could be as small as 1/2 to 1 acre each. Smaller cells will be grazed faster and more uniformly than larger cells. Remember that horses need more space than cattle or other livestock for social interactions. Rotational grazing is not the best system for yearling or young horses because they tend to be rambunctious and need lots of room to run.  

Read How to Make Rotational Grazing Work on Your Horse Farm for more tips.

How to Calculate Stocking Rates for Pastures

A mature cow or horse that weighs 1,000 pounds will consume approximately 600 pounds of dry matter forage (the weight of the forage with water removed) each month. A pasture planted with orchard grass and some clover will produce 2 to 5 ton/acre/year of forage, depending on rain fall, soil type, species of plants, fertilization, and management. All of these factors can increase pasture production yields. Most horses require somewhere between 2-4 acres of pasture land a year to supply all the forage necessary keep the horse and the pasture plants healthy.

Pennsylvania pastures that receive adequate rainfall will grow more forage than dry land pasture. Therefore, less acreage is needed to meet the grazing needs of each horse. However, only a portion of the total yield produced will be eaten. 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 regrowth. This portion varies but averages about 50% of the pastures, thus we refer to it as the "take half, leave half" rule. Remember, with year-round turnout, you must supplement with hay during periods of snow cover or when feed is not available. Continuous grazing of small pastures may require a recovery period of no grazing to maintain forage health and vigor.

Assuming a 1,000 pound animal consumes 600 pounds per month on a pasture which yields 3 tons/acre/year and 50% of the pasture forage remains uneaten, the animal would need approximately 2.4 acres.  Here is the calculation (DM means dry matter):

• 600 lbs x 12 months = 7,200 lbs DM forage consumed annually
• 7,200 lbs / 50% (take half, leave half) = 14,400 lbs DM forage needed annually
• 14,400 lbs / 2,000 lbs = 7.2 tons forage annually
• 7.2 tons / 3 tons per acre pasture yield = 2.4 acres per animal needed to provide adequate feed

Conclusion

There are many factors to consider when selecting a grazing system for livestock. Continuous grazing will often lead to overgrazed areas within the pasture and will require more frequent renovation. Rotational grazing aims to minimize overgrazing and use pastures more efficiently, but does take some additional management and setup. Whichever system you choose, remember the importance of allowing forages a rest period to regrow and recover from grazing.