What is a managed grazing program, and what does it entail? The answer lies in the first word of the phrase – managed. The underlying principle is to manage livestock in a manner that controls the timing and extent of grazing of forage plants so that the pasture provides a reliable source of forage of the appropriate quality throughout the growing season.

Control of when, how often and how much of the forage plant is defoliated by livestock has a large influence on its productivity. Cool-season, perennial grasses generally benefit from an uninterrupted period of growth after defoliation before being grazed again, which is usually when grass tillers have produced three or more leaves. These grasses may tolerate occasional severe defoliation similar to when alfalfa is cut for hay, where little or no leaf area remains after harvest.

Unlike alfalfa, however, grasses produce new leaves from carbohydrates stored in the stem base and from carbohydrates produced by leaves that remain after grazing. Thus, severe defoliation that removes all of the leaf area and most of the stem will likely weaken the plant and reduce persistence. The more frequently severe defoliation occurs, similar to what often occurs in continuously stocked pastures, the greater the stress placed on the plant. Factors beyond the control of the producer such as drought and winter severity often compound the negative effect of poor grazing management.

Producers should consider three factors when trying to determine whether a managed grazing program will work for them:

1. personal goals and philosophy regarding grazing and livestock management

2. land resources

3. type and class of livestock to be grazed

From a personal perspective, a producer should consider the level of time and financial resources he or she is willing to invest in grazing. A managed grazing program will usually require additional permanent or temporary fencing and additional time to monitor pastures and move livestock at the appropriate time. Depending on the current condition of pastures, producers may also need to amend soil fertility, construct lanes for livestock movement and account for soil physical properties such as poor drainage that limit pasture growth. The need to reseed pastures with more productive species is not necessarily a given, since grasses that are best adapted to the type of management imposed will tend to flourish.

A managed grazing program also does not imply that pastures must be managed so that livestock always graze immature, high-quality forage. Producers should consider the nutritional needs of their livestock and the contribution of non-pasture feed sources to their diet before implementing a particular grazing program. Grasses may be grazed at a more mature stage and still meet livestock intake and nutrient requirements. While a managed grazing program offers great flexibility for scheduling when and how often pastures are grazed, an important objective to remember is to manage for the plant’s health as much as possible. Grazing pastures too often and too short may delay the need to feed stored feeds, but may ultimately require more stored feed later on due to poor pasture productivity.

Perennial grasses typically constitute the major component of managed pastures, although legumes and forbs can improve forage quality, seasonal yield distribution and the biodiversity of flora and associated fauna. The major advantage of perennial grasses is that the recurring cost of establishing annuals is avoided, which also reduces the potential for soil erosion associated with tillage.

Perennial grasses have the potential to remain productive year after year, increasing in density by vegetative reproduction through tillers (upright stems), stolons (above-ground runners) or rhizomes (underground runners). Dense grass sods decrease the prevalence of weeds as well. Some perennial grasses have high tolerance to livestock traffic, making them particularly valuable when livestock are kept on pasture during the winter and spring.

Appropriately managed perennial grass pastures are a reliable source of high-quality feed, and stockpiled grass forage can provide feed after growth has ceased in the fall or pastures are covered with snow. Due to their extensive root system and above-ground growth, a permanent sod has beneficial effects on soil properties, such as improved nutrient recycling, organic matter content, water-holding capacity and reduced runoff.

Finally, a less tangible benefit of utilizing perennial grasses in a managed grazing program, but an important one from the perspective of general society, is that they possess an aesthetically pleasing appearance in the landscape, particularly when associated with grazing livestock.  FG

Geoffrey Brink
U.S. Dairy Forage Research Center