Mount & Blade II Bannerlord: Villages and Resources just go to any fief (any village that is nearer even if it owed by the enemy and they are not indifferent to you) and find the village elder. Most villages don't have cattle so it may take a few.
You can get cattle by going to the village elder and select the 'buying supplies' option. Then you run behind them and get on their flanks when you wish to turn them. You can also win them as tournament prizes. You can buy cows from a Farmstead that go into your inventory and produce butter.
