Overgrazing happens when an individual plant is re grazed before it has fully recovered from the previous grazing. It's not the same as severe grazing where if adequate rest is given, promotes leaf production and a better leaf to stem ratio that allows the plant to be more productive.
Under Total grazing we strive to harvest as high a % as possible and in practice we usually achieve 80-90% harvest efficiency. This is very high as when machine cutting for hay harvest efficiency is usually lower.
Under Selective grazing cattle harvest, by definition, a lower quantity of forage than under Total Grazing, usually 30-50%.
Let’s think about the consequences of this.
Under Selective grazing, where they harvest only 30% of available forage means that only one third of the available cow/days is harvested by the cattle.
The cow/days harvested per acre determines, in a given area, how many days pass between grazing and the herd returning, which is the rest period.
Harvesting 90% of available forage gives us a rest period that is 3 times longer than only harvesting 30%. When we have high stocking rates, which is necessary for profitability, the herd needs to return to re-graze the first paddock before it has recovered in a dry year. In dry years bare areas start to form in dry environments and a change in species composition to undesirables in humid environments.
On the other hand, with Total grazing this does not happen, and we can even stockpile complete paddocks of the ranch, thanks to the longer rest periods even in dry years.
Some may say: but the forage quality will be lower, we will address this in future blogs.
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