Patch Grazing and SustainableRangeland ProductionC. Wayne Hanselka, Robert Lyons and Richard Teague

Professor and Extension Range Specialist; Associate Professor and Extension Range Specialist; and Associate Professor and Research Scientist, Texas A&M University System

E-17210-02

Grazing distribution is a major concern to livestock produc-ers because uneven grazing reduces grazeable acres andcarrying capacity. Patch grazing is the close and repeatedgrazing of small patches and/or individual plants, whileadjacent patches or individual plants (often the samespecies) are left ungrazed or lightly grazed.

Patch grazing causes tall perennial grasses to be replacedby shorter perennial grasses, then with annual grasses untilbare ground is finally exposed. More productive species areprogressively replaced by less productive and less palatablespecies, causing a decrease in water infiltration and anincrease in runoff and erosion.

Livestock do not graze randomly. Site preference or grazingdistribution is influenced by living and non-living factors.Living factors include plant types (grasses, forbs, cacti andwoody plants), species and maturity; forage quantity, quali-ty and palatability; animal behavior; and insect pests, pred-ators and human activity. Non-living factors include weath-er, soil/topography, shade and shelter, water, salt and fenc-ing. The greater the variation among landscape areas (vege-tation, topography, etc.), the more likely animals are tograze some areas and avoid others.

Grazing Behavior

Grazing consists of searching for, selecting, grasping andtaking the selected forage into the mouth. Grazing animalsprefer new green leaves. When new green leaves are notpresent, they will eat older green leaves, followed by greenstems, then dry leaves and, finally, dry stems.

The preference for green plant material remains untilalmost no green is left. This “chasing green material”explains why cattle often lose body condition during springgreen-up. Their preference for new growth overrides theirdesire to eat quickly until full. Grazing animals also searchfor plants they consider palatable, and they can be veryselective in the species of plants they eat. They are morelikely to graze preferred forages, to take more bites fromthose plants each visit, and to graze those plants againbefore eating other forages.

If green material is present, but only in small quantities,then forage intake is low. Although available forage may beplentiful, intake may be low because livestock prefers thehigher quality green material.

Studies of cattle suggest that livestock quickly explore newpastures and develop map-like representations of the differ-ent areas within a pasture. This information is stored intheir long-term memories. An animal’s expectations of anarea based on long-term memory changes at a slower ratethan changes in forage quality and quantity. Therefore, theytypically return to areas previously grazed. Grazing ani-mals appear to use short-term memory to remember whichareas they have recently visited and selectively avoid orreturn to those areas again. Memories of where they haverecently foraged may last up to 8 hours.

Day-to-day cattle movement is not by chance. Cattle rarelystay in the same location for more than two consecutivedays. In pastures where forage quantity and quality vary,cattle may not return to sites with low quality forage for aslong as 21 consecutive days.

Development of Patch Grazing

Patch grazing is prevalent on sites with high plant densityand productivity and where species with contrastingpalatabilities are present. Sites that are ungrazed one yearalso tend to be ungrazed the next year. Ungrazed patches insummer develop on the patches that are not grazed at thebeginning of the season. Wolf (large ungrazed) plants tendto develop if grazing in the spring is delayed too long.

Cattle generally avoid forage contaminated with their ownfeces or forage growing near fecal pats. Forage areas thatare avoided can be several times as large as the actual con-taminated area. With continuous grazing, rejected areas cancover significant portions of a pasture from two to severalmonths. In contrast, sheep are not as sensitive to their owndroppings or to the droppings of other species.

As a result, patch grazing develops in a pasture following asequence. Livestock entering a new pasture establish an ini-tial pattern of use that is reinforced as the season progress-es. Animals are then attracted to previously grazed areas,thereby enlarging those and creating adjacent new ones.Patches that were previously heavily grazed are more likelyto be heavily used in subsequent years, and areas previous-ly neglected by livestock will likely receive little subsequentuse. These patterns are more pronounced under lightergrazing pressures and longer grazing periods.

Rangeland Risk Management for Texans

Overuse causes soil loss, more bare ground, replacement ofnormally dominant perennial grasses, lower soil water contentand depressed forage production. In spite of this deterioration,heavily grazed patches may continue to be more heavilygrazed than adjacent patches in better condition because theregrowth is less mature and more nutritious. Grazed patcheswill also have higher annual variability in plant productionthan less-degraded sites, with almost no forage being pro-duced in drought years. Resting such areas during a droughtor even during median rainfall years may not assist recovery ifa patch has significantly deteriorated. The patch size mayexpand even without further grazing because of continued soilerosion.

Overcoming Patch Grazing

Uneven grazing and the development of relatively stable,degraded patches can be serious problems associated withcontinuous grazing, especially in large pastures. Livestockgrazing a large pasture tend to repeatedly neglect or lightlyuse some areas of the pasture while overusing other areas. Thelarger the pasture and the lower the stocking density, thegreater the proportion of pasture neglected. Heavily grazedpatches often occur within preferred plant communities orspecies, close to water sources and within preferred sites.

Managers must minimize the effects of patch grazing andimprove the use of undergrazed areas. Forage should be mod-erately defoliated when a pasture is grazed. Producers can provide water facilities so that all grazing is within one mileand, preferably, one-half mile of water. They can separate pre-ferred from less-preferred landscape areas or plant communi-ties with fences, spread grazing pressure over the pasture withsupplemental minerals or feed, and use multiple species ofgrazing animals. They can increase opportunities for grass toregrow by decreasing pasture size, increasing stock densityand rotating livestock from pasture to pasture.

However, while such measures may alleviate problems causedby patch overgrazing, they do not correct the root of the prob-lem. Under continuous grazing, selected patches may remainmore heavily grazed and not get adequate rest between defoli-ations. By providing periodic rests from defoliation, rotationalgrazing may minimize the effects of patch overgrazing andallow recovery from damage. Consequently, planned rotationalgrazing is a key tool for using and restoring rangeland.

Several approaches have been suggested to reduce patch graz-ing. One method is to graze pastures using high stock densitiesat the beginning of the growing season. This produces moreeven grazing, which reduces patch formation.

Mowing or shredding and burning have also been used toremove old growth. This reduces or eliminates old patches andimproves access to new growth on previously unused areas ofthe pasture, which can reduce patch formation.

Another way to improve grazing distribution and use is by“management intensive grazing.” This requires numerous pas-tures and one herd of livestock. It is critical that forage use beconservative to moderate (35-45 percent) during each grazingevent, even though animal density and grazing pressure ishigh. Move animals from pasture to pasture relatively quicklywith short grazing periods. Use numerous, small pastures toachieve high stock density, with relatively short grazing peri-ods to prevent heavy use. Smaller pastures increase the oppor-tunity to improve forage use, although uneven grazing distri-bution may never be eliminated. Once animals have movedthrough the entire sequence of pastures, they are more likely toexplore and graze all the landscape.

Conservative to moderate grazing during short periods, evenof palatable plant species, preserves the vigor of desirableplants. Long rest periods encourage the growth of plants thatare particularly sensitive to grazing, thereby maintaining orincreasing species diversity.

Although the appropriate number of pastures and the lengthof the grazing and rest periods must be determined for eachindividual situation, high stock densities to achieve controlled,selective grazing should be emphasized. High stock densities,avoiding heavy use at the same time, require short grazingperiods in numerous pastures. If conservative to moderatestocking rates are used, this approach can benefit most ranches.

Texas Cooperative Extension publications are available athttp://texaserc.tamu.edu.

For additional Range Management information, see http://tex-nat.tamu.edu.

For Risk Management information, see http://trmep.tamu.edu.

Support for this publication series wasprovided by the Texas CooperativeExtension risk management initiative.

RiskManagement Education

™

Figure 1. Patch grazing develops on grasslands with species of contrasting

palatabilities.