I am assuming those are cheaper/more efficient. After all, our grain production relies heavily on petrochemical inputs.
Historically speaking, one of the reasons[1] domestication of large herbivores for meat production makes sense is because those can be fed with agriculture byproducts not suitable for human consumption. In industrial terms, it is a sort of "rejects reprocessing" that partially recovers an investment that was already lost.
Nowadays, we feed our animals with human suitable food, which is possible due to the (cost) efficiency gains of the green revolution, which originally was mostly about petrochemicals.
[1] the other being that in nomad societies, they constitute a food store that can carry its own weight around.