Rotational grazing is one of the best ways to maximize forage utilization by managing stocking rate and pasture size.  The reality is pasture ground is hard to find and quite valuable.  In some area, I see planters working fields that had been pasture for the last 50 years.  With rotational grazing the concept is to divide the grazing area into paddocks that a group of animals can consume within 7 to 10 days.  

Rotational grazing allows you to run more cows per acre while matching grass growth rates to stocking rate.  Table 1.  Shows how improving percent pasture utilization from 60% to 90% will increase the capacity from 0.67 to 1.0  cows/year.  In rotation grazing systems, we often see pasture yield increase.  This can be explained by the benefits of better weed control, more even manure distribution and maintaining the grass in a vegetative state longer during the growing season. In the example below increasing pasture yield from 5000 to 7000 DM pounds allowed the stocking rate to increase by nearly 0.3 to 0.4 cows per year.

Table 1.  Carrying Capacity and Forage Available at Various Utilization Rates

The best advice for using rotational grazing is to learn the basics and then apply those principals to your specific operation.  Major considerations are water access, animal numbers, how many paddocks to utilize, time constraints and fencing options.  Mother Nature is in control and seasonal grass growth rates and moisture availability will impact the length and frequency of grazing each paddock.

Considerations for a rotational grazing system are water, animal units, matching stocking rate to grass growth and how each of those factors impact paddock size and layout.

Water
Where is it and how will water location impact paddock size and shape?  Often a drover lane can be utilized for access to multiple paddocks.  Visit with local extension agents or NRCS offices about possible cost share funding for fencing and water systems.

Animal Units
Most of the reference material for grazing will use the terminology of animal unit.  They will have information about stocking rates expressed in acres per animal unit for various grass types that are modified for growing season.  Generally an animal unit is defined as equivalent to 1000 pounds of animal.  There are some adjustments made for stage of production.   A 1300 pound dry cow would be 1.3 animal units but a lactation cow in the first 4 months would be 1.6 animal units. 

Considerations For Yield Variation
Fast spring growth of grass will often allow for some paddocks to be skipped in the grazing rotation and saved for hay production.  Typically acres needed per animal unit will be 0.3 to 0.5 units lower in the spring due to increased productivity compared to the drier summer months.  For example, an orchard grass pasture can be grazed at 0.7 acres/animal unit in the spring, but in August 1.25 acres/animal unit is needed.  This variation can be managed by changing animal numbers or changing paddock size.  In a system where there are 4 similar sized paddocks, one paddock is saved for hay and the other 3 grazed.  In the drier months when grass growth declines, two lots at once would be grazed at the same time.

Timing and Fencing
Pasture in the Midwest with cool season grasses will have about 300 pounds of forage per inch of growth and length of the grazing period will vary by animal number and growth rate.  Common rest periods or time between grazing is 14-21 days during the spring and 40-60 days in warmer months.  Internal temporary fencing is a great tool for managing animal access to the different paddocks.  A practice in some areas is to have a front and back fence that are each moved on a 10-14 day schedule.  

The economic value of getting maximum utilization of the pasture has significant impact on profitability.  The forage that the cow herd harvests by grazing is the most economical feed you have.  With pasture value increasing and pasture availability being a concern, you may want to consider rotation grazing.  Grass type and carrying capacity will vary around the country.  Suppliers of fencing equipment pasture walks and grazing days are great sources of information.  Visit with your local extension specialist and NRCS representative to see what is available and working in your part of the country.