Generally one cow requires 3 acres.
You alternate the cow on acres 1 & 2- it forages on one while the other regrows.
Third acre is to cut for winter hay storage.
Chickens depend on what you're trying to do.
If you're collecting eggs then they need a coop so they lay eggs in a nesting box instead of under a random bush out in the yard.
If you're raising to eat then they can free roam (you'll slaughter before they're old enough to lay eggs anyways). Some breeds are better at predator avoidance (more alert, will warn other chickens instead of just running away and hiding). All chickens need to be kept out of the garden but they're beneficial in a corn field because they'll eat insects and weeds but once the corn is about 2 feet tall they won't eat the corn leaves.
Daily chores is watering (even you have automatic waterers you need to verify everything is functioning) and supplemental feed.
Chickens or cows you're look at about 20 minutes each a day. Once you get in a rhythm its very easy to make rounds. Every few days you need another 30 minutes to clean chicken shit out of coops.
And yes, I'm a farmer.