I'm out of the loop, I don't know much about grazing pastures. But some grasses, grown intentionally, grow extremely fast (giganteus miscanthus was the big one

I'm out of the loop, I don't know much about grazing pastures. But some grasses, grown intentionally, grow extremely fast (giganteus miscanthus was the big one at the time I was researching actively). https://en.wikipedia.org/wiki/Miscanthus_%C3%97_giganteus https://en.wikipedia.org/wiki/Miscanthus_%C3%97_giganteus I'm certain there are better ones now, this is very dated information about the details. But from the Wikipedia there's some exciting stuff to me: "Miscanthus is unusually efficient at turning solar radiation into biomass, and its water use efficiency is among the highest of any crop. It has twice the water use efficiency of its fellow C4 plant maize, twice the efficiency as the C3 energy crop willow (Salix viminalis), and four times the efficiency as the C3 plant wheat." and check out just how tolerant this species is -- "Miscanthus × giganteus is either moderately or highly tolerant of heat, drought, flooding, salinity (below 100 mM), and cool soil temperatures (down to −3.4°C, or 25°F). This robustness makes it possible to establish relatively high-yielding miscanthus fields on marginal land, for instance in coastal areas, damp habitats, grasslands, abandoned milling sites, forest edges, streamsides, foothills and mountain slopes. 99% of Europe's saline, marginal lands can be used for M. × giganteus plantations, with only an expected maximum yield loss of 11%." It's pretty amazing, and is already grown for fuels according to the wikipedia page so it's not like it's a novel concept.