There is a big difference is growing plants for human consumption when compared ...

There is a big difference is growing plants for human consumption when compared to growing feed for an animals and then consuming the animal meat.

Basic biology says that when cattle eat feed only of portion of that feed ends up as meat.

The farming industry actually measures this using a measure called the Feed Conversion Ratio.

For example the FCR for cattle is over 4 meaning for every unit of animal mass you'll need over 4 times that mass in feed.

This basic biology means it is always be more efficient to grow vegetables for direct consumption than to grow them for animal feed.