@graventhe - Okay, I can understand the confusion. I bet you're wondering how I jumped from removing the rabbit holes (which only the sims need) to outlining a few pitfalls of a rabbit hole-less world where the animals and other points of Sim life are concerned. My apologies for the confusion.
I should have started with -- when developing a rabbit hole-less game, it all depends on the type of world you begin with. If you start with a blank unpopulated world, then there are no spawning plants (usually) for the animals to feed on. The animals become dependent on you to provide for them, but only when in the game world.
Think of it this way, you know how townies, despite having access to various food sources readily available to them such as quick meals, picnic baskets and tables (even the kitchen at their houses) will be seen around town screaming of starvation? The same holds true for the animals when there are no food sources available. They can drink all the water they want to temporarily alleviate hunger (like sims do with the juice bar), but it doesn't sustain them for long.
And, contrary to common belief, the game does not provide for their needs while they are in the world; animals are handled just like any other Sim. They have to find food for themselves. If things become too bad, the game will generally pull them back and they will disappear for a while and return the next day. Otherwise, if not pulled back in time, they will die in-game and you'll find the tombstone of the deceased animal. Thankfully, that does not happen often, but it does happen. This is why I suggested making a plan when setting up the world.
However, things work a little bit differently when you are reducing an already developed world, such as Sunset Valley down to a rabbit hole-less one which is more under your control. A developed world comes with pre-built in 'back-up' plans. Such as renewable food sources on community lots and residential lots with unguarded plants for the animals (and sims) to take advantage of (and plenty of fish).
When using this kind of world, keep in mind, any essential thing which is removed has to be replaced with a sustainable equivalent. When you take away the grocery stores, you take away the food source only for your sims.
Townies don't really shop at the store; they are just directed there to give the impression and illusion of daily life when food shopping. While out in town when townies get hungry, unless called to another location, they will head to the nearest picnic basket, picnic table, fire pit, or community grill to get or make a meal. Otherwise, they cook at home or go into suspended animation while their needs are refreshed. This is why the town won't die of starvation.
However, for your Sim, with the grocery store gone, you now have two options available to you for food; start a garden or forge off of the land.
If you choose to forge off of the land, your Sim is now in direct competition with the animal population for food as plants only renew randomly once a day (with no death or decay just dormancy if Seasons is active). This means there is a limited amount of food resources to be shared at any given time. The more a community lot plant is harvested from or eaten, the slower its regenerative cycle becomes. When the world plants slow down, the strain is felt.
One of the ways to keep things a bit more balanced when the world's plants aren't producing as much as they normally would is to feed the animals. This can be done in a couple of ways, using the 'buyDebug' cheat place a few fully harvestable plants down for them to 'destroy' (eat). Or make animal food and leave it in accessible areas. I do this all the time with the horses. I make granola and leave it around town for them to find (and they always find and eat it).
Or, if modded, the whole thing can be avoided by simply turning off the animal population preventing them from spawning.
Hope this helps clear up any misunderstandings. The other points I made are suggestion on how to navigate without the rabbit holes which handles things like, jobs, schools, hospitals and social events. There are always two or three manual ways around everything in this game, it all depends on how deep or realistic the player is wanting and willing to go.