Upgrade the coop and animal shed, for animals in particular. I haven't had a lot of problems with my Sims being too tired/busy with the animals, but probably your best bets are automation mechanics.
Upgraded coops and sheds will feed your animals; sprinklers and hydroponic planters will water your garden; befriended birds and rabbits (and golden chickens) and Patchy the scarecrow will help with garden chores.
Usually my garden is more of a time sink than the animals, and if that is the case for you I seriously suggest abandoning giant crops. Even with gardening help, they can be annoying and high maintenance.
If you're interested in smaller changes for efficiency, I would also upgrade your furniture for better use returns.
