|More affluent Chinese consumers eating beef|
China has a small amount of arable land when compared to it's population. Not to mention it has a huge pollution problem which is shrinking that amount of land every year.
If you combine that with climate change, and the limiting of fresh water and arable land, then it makes perfect sense why China is trying to get ahead of this now. It's much easier and efficient to grow vegetables than to grow full-grown animals. Also they are at least shrinking their pollution rates by some level and thus slowing the effects somewhat.