Last week when I was at the Nebraska Grazing Conference in Kearney I heard two or three things that were inaccurate on the surface.
The conference was great, as usual, but the thing that bothered me most was a misstatement about "mob" grazing or ultra-high stock-density grazing and the timing of moves. The statement hangs in my memory as an ambiguity so instead of calling it out I'll just get straight to the facts.
Time in a paddock is almost perfectly inverse to the amount of space (and therefore forage) given animals in that paddock, also known as stock density.
* The more room and forage they have the longer they can stay and still have groceries.
* The less room and therefore less amount of forage they have the less time they can stay without running out of groceries.
Click on the video to see a graphic representation of this principle.
The only things that keep this principle from being perfectly inverse are facts about grazing efficiency. Under very high stock density animals eat more competitively and consume some plants they otherwise might not. They also tend to eat a greater proportion of plants they might otherwise dung or urinate upon or trample and not consume.
Still, it's best to just think of this as an inverse relationship and plan moves accordingly.
Another way to understand this stock-density-to-time relationship is to think of it as a mathematical salad bar.
A herd of cattle will consume a given percentage of their body weight every day; let's call it them the crowd consumption.
A given amount of land acreage will only have so much forage on it, depending on location, rainfall and species makeup. Let's call that the salad bar.
The simplified question is how long will it take for the appetite of the crowd of cattle to clean out the salad bar. Pounds of salad bar supplied divided by pounds of consumption by the crowd equals time of grazing.
How long would it take 20 people to strip a small salad bar clean if that's all they had to eat?
How long would it take 150 people to strip that same salad bar clean if that's all they had to eat?
Further, when long-term stocking rate is correct, here's another relationship: The more paddocks you have the shorter the graze period and the longer the rest periods.
This is a key understanding. If you don't get it right you will get terrible animal performance.
Moreover, the top part of forage plants is the highest quality and gives the best gains, body condition or milk production. If you leave cattle in a paddock beyond the point where they are eating the best forage you kill performance.
Further, if you leave them very long under ultra-high stock density they will eat all the forage and be hungry you will actually keep them from getting enough to eat and their performance will go into negative numbers.
There is some great information on managed grazing in the August edition of Beef Producer in your local Farm Progress magazine or you can find it in the archives of www.BeefProducer.com.