So cattle eat things that humans cannot and convert them into things we can. They poop and urinate to fertilise the place, graze in places not suitable for crops, churn the soil as they move about and it turns out plants needs to be grazed. All this is easily searchable information. Bear in mind I am not talking about factory cattle, which is a cruel and awful practice that probably should be banned.

This article lays out the argument pretty well for example.