You don't need it if they are a strictly prepared crumble/pellet diet, but it doesn't hurt to have the grit available all the time.
The reason crumbles/pellets don't require grit is that they naturally will dissolve into mush in water, which means they'll do the same in the chicken digestive system. No grit is needed to physically break it down and their digestive enzymes can do all the remaining work.
When you feed your chickens other foods (fruit, whole grains, grass, insects, worms, etc), their digestive systems need the additional help to physically break down those larger chunks of food. That is where the grit and gizzard handle the work that our teeth do.
The reason crumbles/pellets don't require grit is that they naturally will dissolve into mush in water, which means they'll do the same in the chicken digestive system. No grit is needed to physically break it down and their digestive enzymes can do all the remaining work.
When you feed your chickens other foods (fruit, whole grains, grass, insects, worms, etc), their digestive systems need the additional help to physically break down those larger chunks of food. That is where the grit and gizzard handle the work that our teeth do.
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