Should one perform Kaparos with chickens if the chickens will not be eaten by people but used as animal fodder?
It is still preferable to perform Kaparos with a chicken even in such a case.[1] Nonetheless, in the above scenario, it is best to give Pidyon Kaparos to the poor.[2] The chickens are to be slaughtered regularly with a blessing and a blessing is to be recited over the covering of the blood.[3]
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[1] As the giving the chicken to the poor is an additional Minhag that was added to Kaparos. The main minhag of Kaparos is to sweeten the Gevuros through a Kosher Shechita, irrelevant of what is done afterwards. Thus its ruled in Achronim that if the Shechita was Kosher but the bird was a Treifa it is still valid. See Shaar Hakolel 42:2
[2] See Admur 605:6
[3] See Michaber 18:18; Simla Chadasha 19:1; 28:22; Shulchan Gavoa 28:41