Management of Intensive Livestock Grazing
What intensive grazing really means
This fact sheet discusses some of the aspects of Management of Intensive Livestock Grazing.
History of intensive grazing
In Britain and throughout Europe, intensive grazing practices go back over 500 years. Here, population pressures demanded greater productivity from the agricultural land base. The use of rotational grazing, tame forage species and fertilizer became established and accepted practices.
Early ranching enterprises in North America also practiced a form of intensive grazing management. Livestock, unrestricted by fences and property boundaries, moved as forage supplies depleted, and by default, the range received rest periods. However, as fencing use became widespread, season-long, continuous-use grazing became accepted. This produced many of the problems now associated with poor grazing management. Modern livestock producers are rediscovering the value of intensive management of livestock grazing.
Goal of range and pasture management
Long-term successful grazing systems must do the following:
Impacts of poor grazing management
Excessive defoliation results in desirable forage plants being replaced by less desirable species and reduction of surface litter levels, resulting in increased amounts of bare ground and risk of soil erosion. The water and mineral cycles cease to function efficiently and overall range and pasture productivity declines.
Livestock show other behaviours that directly influence grazing. They are reluctant to use slopes exceeding 15 per cent, and in rolling terrain seldom graze at elevations greater than 70 metres above water. Grazing is also limited by the horizontal distance from water. Livestock rarely graze further than 2.5 km from water. They readily seek shade during hot summer periods, resulting in high usage of forested and riparian areas.
Controlling livestock behaviour improves animal distribution and plant use. Fencing, salt/mineral placement, herding, and water development are used to influence where and what animals graze.
Grazing systems control time, intensity and frequency of grazing on individual plants.
Principles of intensive grazing
Adequate regrowth is an important concept in understanding how the plant behaves under intensive grazing. It is best explained using two plotted curves that describe carbohydrate (or food storage) and overall plant growth.
The carbohydrate storage curve shows seasonal fluctuations through the various development of phenological stages of a plant. Figure 1 shows how carbohydrate levels hit a low at the two to four leaf stage. Grass plants die if grazed repeatedly at this stage without allowing carbohydrate build-ups.
Figure 1. The carbohydrate storage curve of a typical cool season grass plant. Carbohydrate reserves reach a low point at the two to four leaf stage, and peak at seed ripe.
Root growth stops within 24 hours of severe defoliation. When moisture conditions are unfavourable, growth may not resume that season. This places the plant at a competitive disadvantage compared to other ungrazed plants in the sward. In general, leaving 50 per cent of the green leaf area will minimize the time period in which roots do not grow.
Figure 2 The sigmoid (S) growth curve of a typical forage stand indicates how yield, growth rates and rest periods change over the growing season. (Voisin 1988).
Andre Voisin, an early intensive grazing researcher, found that forage production follows a sigmoid or "S-shaped" growth pattern (Figure 2). He noted that growth was slow in the initial stages of plant growth, increasing rapidly during the central period and slowing again as leaves die.
Figure 2 Growth shows that the amount of time needed by an individual plant to recover from grazing varies with a number of factors. Significant and timely rainfall and/or temperatures will speed growth or regrowth, thus altering required recovery time. Conversely harsh conditions necessitate longer rest periods. Grazing intervals and rest periods must therefore be altered according to rate of growth which is in turn governed by environmental conditions and the vigour of the plant. Healthy plants recover most quickly.
Harvesting by livestock
The Saskatchewan Experience
Figure 3 The relationship between stocking rate and production. Individual animal performance is highest at a low stocking rate and lowest when overstocking occurs. Maximum gain per acre is achieved at a moderate stocking rate.
Relationship between stock density and meat production
However, there is a point above which overall production declines and the land becomes overstocked. Managers must watch their grazing lands closely and seek to maintain the delicate relationship between stock density and beef production.
When implementing intensive grazing, try to:
Remember, each situation is different. Only you can decide what is best for your operation.
Animal Unit Month (AUM) - the amount of forage consumed by a 1,000 pound cow, with or without calf, in one month.
Grazing system - the manipulation of livestock in a planned manner in order to accomplish a desired goal.
Preference - selective grazing exhibited by animals when confronted with choices.
Riparian Areas - The lushly vegetated zones in coulees and alongside rivers, creeks, lakes, sloughs, potholes, hay meadows and springs.
Stocking rate - the number of animals on a unit area of land during a month or a grazing season. This is usually expressed in AUMS/acre or AUMS/quarter.
Stocking density - the number of animals on a given area of land at a moment in time.
References and Suggested Readings
Saskatchewan Agriculture Development Fund, 2008. Managing Saskatchewan Rangelands. updated.