You have a solution with cows if you want it for your update without waiting for Revamp. Don't use "cattle" in your recipe but COW_HOLSTEIN and change the beef liters to 500 (and 75 fat). and in the sellingstation part use filltypeconversion with 1 or 2 in ratio. Then angus and other "beef cattle" will give 1000 liters and milky only 500.
Of course if you play with mods which add more animals types it wont work.
Edit: oups, just a minute too late ^^