Cows are picky if given the opportunity to selectively graze. They will return to the most delicious grasses as soon as new growth appears while letting the less palatable (but equally nutritious) grasses reach maturity (thus no longer nutritious), seed and eventually crowd out the good stuff. With the Managed Intensive Rotational Grazing (MIRG) system, the animals are given the exact amount of pasture that they can eat in 24 hours before being moved to a fresh paddock which encourages the animals to take a more “mowing” approach opposed to selective. Each paddock is rested until it regenerates.
Grass grows on an “S” curve as demonstrated by this excerpt from the California Grazing Association’s publication titled Principles of Controlled Grazing (PDF):
Since I am working with so little land (~6 Acres with trees removed), I want to manage it as efficiently as possible. The next question is how much do I let the grazers mow the paddocks? According to these fantastic demonstrations on Forage Decision Aids by the University of Kentucky, we can directly compare the regeneration of Orchard Grass of the 6 days following simulated grazing to 3.5 inches vs mowed all the way down to 1″.
Combined with various different university studies, most grasses regenerate best when grazed to ~10 cm. At this length, grasses retain enough photosynthetic tissue to create the energy required for regrowth without having to use reserves stored in the root system.