Do you use salt in your rendering process? Were you thinking of using the scraps left after the rendering or the tallow from the suet? If you 're thinking of the scraps some of them may be salty from the rendering process. I'm not sure if that much salt would be hard on the little chicks.
If you're using the tallow, then there shouldn't be too much salt because I think the rendering process keeps the salt in the drippings, but tallow in itself doesn't have a lot of nutritional value unless mixed with grains, seeds, and stuff.
On the advice of someone who should know, I took rendering drippings, mixed them with peanut butter and made my own suet cakes for wild birds. They were a dismal failure. What do you mix in them, Imp, to get the birds to like them. I'm guessing that my chickens would love it because basically they love almost everything (not collard greens) but I'm not sure how good it is for them. I think there's something called fatty liver disease that affects chickens fed a diet high in fat.
Perhaps others have had different experiences.
Mary