>Just in terms of land-use, livestock is several times less efficient than other kinds of agriculture for the same food output.

This assumes that the land is equally usable for both activities. Many times, it isn't: a lot of land that's good enough for grazing cows doesn't have enough water available for growing plants that people want to (or can) eat. People can't eat grass.

This probably isn't an issue in Denmark, but in many other places it is.

Cows are extremely inefficient (2% conversion) at converting calories to meat, so putting cows on that land is also an inefficient use of that land. And land with bad yield for crops also has bad yield for cows and the grass they eat and the water they need. I don't see the proposition being made in these claims.

Cows are so inefficient that we don't need to use marginal land at all to grow food. The majority of arable land is already used for cows yet they produce a disproportionately small amount of food. Weening off cows is a good thing.

Cows still need water from somewhere in those areas you’re talking about. If the land is particularly poor it also won’t produce enough feed and will have to be supplemented with feed that requires water and energy to grow somewhere else.

It also ignores that animals produce the manure that is used to fertilize soil to grow crops in.