I'm old time Tennessee and everything here eats lard
I wouldn't just feed them gobs of it but, in moderation it shouldn't hurt them . get some corn meal and bake them a pone of bread once a week or so with lard in it if you have surplus lard.
I wouldn't feed mine lard, but someone else may know more than i do about chickens, these are the first i've had in probably close to 30 years but I never did feed them meat,potato peelings or anything greasy,