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David W. Pratt, U.C.C.E. Farm Advisor
Reference: Livestock & Range Report No. 962 Summer 1996
Many ranchers using rotational grazing make decisions about moving livestock from one paddock to another based on the severity of use in the paddock their stock are currently grazing. When plants are grazed down to a particular height they move on to the next field. They think, "I don’t want to take any more grass out of here…I’d better move the cattle." If this is the way you make decisions about when to move, trouble may be around the corner.
The severity of use in a paddock tells us if we are understocked or overstocked. But it doesn’t tell us anything about the most important aspect of controlled grazing…the management of time. This is one reason why controlled grazing is not rotational grazing.
An old Chinese proverb tells us that "the best fertilizer is the footprint of the owner." Let me add "…but it makes a difference where those footprints are." (I’m not as poetic as most Chinese philosophers.) The feet making your foot prints need to be taking you to the right places.
Controlled graziers have three questions to answer and three places to make footprints when they move stock from one paddock to another.
1. Look Behind: What rest period will I need?
Ranchers using controlled grazing know that the single most important principle of controlled grazing is to adjust the rest period as the growth/recovery rate of pastures changes: slower growth, longer rests. The rest period and the graze period are dependent on each other. To shorten the rest period, we shorten the time stock remain in each paddock. To lengthen the rest period we need to increase the length of time stock stay in each paddock. So, as growth rates change, we will need to adjust the rest and graze periods. That means that before we make decisions about the graze period, we have to know how much rest our pastures need…and that means we need to know how fast our pastures are growing.
How can we tell how fast our pastures are growing? It’s simple. We need to make some footprints in the pastures stock have already grazed. If the paddocks stock left a week or two ago have significant regrowth (a couple of inches), plan on using relatively short rest periods (30 to 45 days). If we don’t see much regrowth, we need to plan for longer rest periods (60 to 120 days).
2. Look Ahead: Has this paddock had enough rest?
The second place to make footprints is the paddock we plan to graze next. We need to make sure the pasture is ready. If it is short of feed, the pasture probably hasn’t had enough rest. To get more rest we may need to keep the cattle where they are a bit longer. Moving livestock in before the pasture is ready may launch us into a vicious cycle of "chasing the grass." Once in the cycle, the cows will find less and less grass waiting for them each time they move. (For more information on this problem read: Out Of Feed: The Vicious Cycle, Solano County UCCE Livestock & Range Report 937.)
3. Where The Livestock Are: Is the stocking rate right?
Our third set of footprints should be in the paddock the stock are currently grazing. The severity of use here tells us if the stocking rate is okay. If grazing is too severe, we are either overstocked or our rest period is too short (we may be in the vicious cycle and not even know it). If we are overstocked, we’d better destock. If the rest period is too short, we’d better lengthen it…that means that moving is exactly the wrong thing to do…we need to stay put.
Controlled graziers try to keep the graze periods short (consistent with the required rest) to keep animal performance high. Increasing the graze period is one way to lengthen the rest period, but there is a better alternative…increase the number of pastures. By subdividing fields we can maintain or increase the rest period while maintaining or shortening the graze period. For example, if we have 8 pastures and need a 50 day rest, our graze periods will be 7 days long. If we divide each of those pastures in half (16 pastures) we can rest paddocks for 60 days with only 4 day graze periods.
50 Days Rest ÷ 7 Paddocks Resting = 7 Day Graze Period
60 Day Rest ÷ 15 Paddocks Resting = 4 Day Graze Period
There is more to controlled grazing than moving animals from one paddock to another.
Remember to make footprints:
To assess the growth rate of pastures and determine the rest period you’ll need to provide.
To see if the paddock is ready for livestock (did it get enough rest?)
3. WHERE THE LIVESTOCK ARE
To see if your stocking rate is appropriate.