Grazing Management: Designing a Rotational System
Excerpt from Publication 19, Pasture Production, Order this publication
Table of Contents
To keep costs reasonable, incorporate the existing fencing into the scheme. All paddocks must have access to water and the layout must accommodate this. An alley system is useful for moving livestock back and forth to a common destination.
Figure 4-1. A field divided for rotational grazing. An alley way allows access to water and handling facilities from all paddocks.
Estimate the productivity of the pastures. Paddocks do not have to be the same size, but it makes it easier to manage them if they have a similar degree of productivity. Divide extremely productive pastures into smaller areas than poorly producing pastures. Set up paddocks on hills to run across the field, rather than up and down. This eliminates the selective grazing that normally takes place on slopes. If given the opportunity, livestock will camp on the top of hills and reject the forage at the bottom.
The number of paddocks required is based on the length of time it takes for the pasture to recover after being grazed. This is essential for keeping the pastures productive. A French scientist, André Voisin, devised the following simple formula to calculate the number of paddocks required for efficient grazing:
Number of paddocks required = (days of rest period / days of grazing in one paddock) + 1
The number of days required for rest differs over the grazing season. In the spring cool season forages grow at twice the rate than they grow in summer. A good working guideline is that it takes 1520 days in the spring and 3040 days in the summer for most forage species to recover after grazing. However, recovery rate is influenced by the individual species, how they have been grazed and the weather. The required rest period fluctuates not only within the season but also from year to year. A good rotational system must be flexible to handle these changes.
The time the animals spend in a paddock must be long enough to graze the pasture off evenly but short enough to prevent grazing of new regrowth. The faster the animals are in and out of a pasture the better in terms of forage production. Seven days is the maximum time that animals should remain in a paddock. The animals should be moved on to the next paddock when it is ready to be grazed even if they have not finished grazing the first. This is to prevent the next field from becoming too mature and being largely wasted by the animals. If the animals cannot keep up to forage production, a hay or silage crop, if possible, should be taken.
Source. R.S. Fulkerson. Ontario Agricultural College, University of Guelph
Shorter grazing periods encourage higher pasture yields.
Because of the differences in recovery rates in the spring and summer, only half the number of paddocks needed in the summer are required in the spring. Hay or silage with half of the spring production is one solution to balancing the forage supply with livestock demand. The other option is to expand the land base for summer grazing by incorporating the aftermath of hay fields. Most pasture systems are more effective if they include grazing hay aftermath, reducing stocking rates in midsummer.
Paddocks work best if they are square, rather than rectangular or irregularly shaped. Long, thin paddocks tend to encourage livestock to graze at the end nearest water, minerals or shade, and to avoid grazing the distant end. Square corners are easier to hay or clip. Design your paddocks to allow access to machinery for carrying out these operations as well as fertilizing.
At the end of each grazing season evaluate the performance of your pastures. If some of the paddocks are regularly not grazed off evenly, then subdivide that specific paddock to encourage better grazing next season.
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