Very few soybeans are used for cattle. The meal from soybeans is used on chickens and pigs. Cattle cannot stomach very much soy at all. They are more likely to be fed some grain, but their diet is 90+% hay and grass even on feed lot cattle. Soy meal is the leftover part of the soy bean. About 20% of a soy bean is used to produce soy oil, which is the primary source of human nutrition in soy. That's what's used to make soy milk, soy protein, etc. The meal component of the bean is not useful for all these other byproducts that soy acts as an ingredient of. So it would be a waste of perfectly good food not to feed that to chickens and pigs.

Land use management in Brazil sounds like an incredibly nuanced topic that I know next to nothing about. I'm much more familiar with American agriculture. And we make most of our own food here, including our own beef.

Source: https://ncsoy.org/media-resources/uses-of-soybeans/