Managing pastures for sheep

The pasture resource is often the most neglected part of the sheep enterprise, yet it usually provides the majority of nutrients to the stock. Well-managed pastures that are properly grazed have the potential to minimize feed costs and increase profits. Pasture is the most natural diet for sheep and other ruminant animals. Though pasture is not without its own risks, fewer digestive problems are usually encountered among grazing sheep and lambs.

Pasture plants
A pasture can be comprised of many different kinds of plants. Which species to plant depends upon the purpose of the pasture, the climate, and soil type. Soil survey maps can help with the latter. The best pastures usually contain a mixture of grasses and legumes. Selecting one or more grass and legume species is usually preferable to commercial pasture mixes which may contain plant species which are not adapted.

Cool season grasses
Cool season grasses form the basis of most sheep pastures. Cool season grasses are annual or perennial plants that begin growth during the fall or winter and grow to spring or early summer. Cool season grasses are not damaged by sub-freezing temperatures. However, they go dormant during hot weather. Common cool season grasses include orchardgrass, Kentucky bluegrass, tall fescue, timothy, reed canarygrass, ryegrass, brome grasses, and wheat grasses.

Tall fescue
Tall fescue is the most important cool season grass in the United States. Most tall fescue is infected with a fungal endophyte that reduces performance in grazing animals and causes reproductive problems in horses. Sheep appear to be less affected by the endophyte than cattle and horses. Animal performance is superior on endophtye-free fescue, but plant persistance suffers. MaxQ™ tall fescue contains a non-toxic endophyte which improves animal performance while maintaining plant performance.

Tall fescue is the most desirable grass to stockpile for late fall and winter grazing. Unlike the summer forage, fall-saved fescue is palatable and high in digestibility. Forage quality losses after frost are less for fescue than other forages. Endophyte toxicity of stockpiled fescue declines with time.

Legume plants are known their ability to fix atmospheric nitrogen. Legumes have a higher protein content than grasses. They fall into two classes: forage and grain. Forage legumes include alfalfa, clovers, birdsfoot trefoil, lespedezas, and vetch. Grain legumes include beans, peas, lupins, kudzu, and peanuts. Pasture legumes improve summer pasture productivity.

Legume pastures (alfalfa and clover) are a common cause of bloat. The phytoestrogens contained in some pasture legumes (e.g. red clover) can cause a decline in ewe fertility.

Sericea lespedeza
The high tannin content of sericea lespedeza gives it an “anthelmintic-like” effect. Fecal egg counts tend to be lower among small ruminants grazing sericea lespedeza pastures, as adult worms lay fewer eggs and the eggs that are produced have reduced hatching ability. Though it shows great promise for helping to control internal parasites in sheep and goats, sericea lespedeza is classified as a noxious weed in some states.

Warm season grasses
Warm season grasses are annual or perennial plants that begin growth during the spring, and grow to summer or fall until frost. Common warm season grasses include bahiagrass, bermuda grass, crabgrass, eastern gamagrass, big bluestem, indiangrass, switchgrass, sudangrass, and pearl millet. Most native grasses are warm season grasses. Sheep have generally not performed as well on warm season grasses as cattle.

An annual is a plant that completes its life cycle in one year. Annuals must be planted every year in order to produce forage for livestock feed. Summer annuals complete their life cycle between spring and fall. Summer annuals include crabgrass, pearl millet, sorghum, sudangrass, and sorghum x sudangrass. Winter annuals complete their life cycle between fall and spring. Winter annuals include wheat, barley, winter oats, rye, and triticale (rye x wheat).

Brassicas are annual crops which can be grazed by sheep. They include rape, kale, swede, and turnips. They are most commonly used to extend the grazing season. Performance on brassicas is improved if dry hay is offered. Lamb performance on brassicas has varied.

Small grains

When properly managed, small grain crops can be used for grazing by sheep and other livestock. Small grains can provide excellent pasture in the fall and early spring. The effect of livestock grazing on small grain yields ranges from yield reductions to increases in yield.

Forbs are non-grasslike, non-woody, flowering herbaceous plants. Forbs are commonly called weeds. They may be classified as annual or perennial, warm season or cool season. When grazing a mixed sward, sheep prefer forbs. Sheep’s preference for forbs makes them well-suited to landscape management.

Browse includes buds, twigs, leaves, fruit and flowers of woody plants (trees and shrubs). While sheep will eat varous browse species, goats are best known for choosing these types of plants.

Crop residues
Crop residues are the materials left in a field after the crop has been harvested. Residues include stalks and stubble, leaves, and seed pods. Crop residues offer a low-cost feeding alternative for sheep, while sheep grazing helps to control pests by disrupting insect life cycles.

Pasture Establishment
Planning for a successful pasture establishment should begin months in advance. It can take years to correct severe soil acidity. If lime is needed, it should be applied six to 12 months prior to seeding.

Different seeding methods can be used to establish a pasture: drilling, cultipacking, and broadcasting. No-tillage involves using herbicides to kill the existing vegetation and then seeding directly into the residue. The seed bed is usually prepared by hay removal or hard grazing

The best time to establish cool season grasses is in the late summer and early fall. Spring plantings have enough moisture for seed germination, but weed pressure is high. Warm season grasses should be planted in late spring to early summer after the soil temperature has reached 65°F or above. Seeding rates depend upon the plant species and seeding method. Certified seed is recommended.

Legume seed may need to be innoculated with the proper bacterial strain.New seedings should not be grazed until the plants have developed sufficient root systems. If you can easily pull a plant from the ground, its root system is not sufficiently developed.

Pasture Renovation
Pasture renovation is when you “renew” a pasture by introducing a desired forage species into the existing plant stand. It should be done on a regular basis, as most legumes tend to be short-lived in a pasture. Overgrazing, poor fertility, and other adverse conditions tend to favor grass plants over legumes.

Frost seeding is a common method of pasture renovation. This is when seed is broadcast into existing pastures during the late winter or early spring when the soil freezes at night, but thaws during the day.

Pasture Maintenance
Maintaining a pasture is similar to maintaining a car. If you want good, long-term performance of your pasture, you need to take steps to properly maintain it. Soil sampling a minimum of every three years is a must. Lime and fertilizer should be applied according to soil test results. Excess lime can cause mineral deficiencies. Excess fertilizer pollutes ground water.

Pastures which are composed of predominantly grass plants should receive nitrogen fertilizer every year. There are numerous sources of inorganic and organic nitrogen. Sheep grazing pastures fertilized with poultry litter or pig manure may be at increased risk for copper toxicity. Pasture which contain 30 percent or more legumes usually do not require nitrogen fertilization.

Broadleaf weeds can be controlled with herbicides and mowing. Controlled grazing and proper soil pH will also help to surpress weed growth.

Poisonous plants
Numerous plants can be poisonous to sheep. Toxicity usually depends upon the growing conditions and stage, plant part, and amount consumed. As a general rule, sheep usually avoid poisonous plants. Problems arise when desirable forages are scarce and poisonous plants are abundant.

The effects produced by the ingestion of poisonous plants are extremely variable and depend upon the poison consumed in the plant. Some poisonous plants cause rapid death. Others produce gastro-enteritis or cause nervous symptoms or locomotion problems. Treatment is usually unrewarding.

By: Susan Schoenian, Extension Sheep & Goat Specialist, University of Maryland