Supportive supplements (liver tonic / vitamins / amino acids) run 3-5 days, max 7 days, then stop — plain clean water + starter feed is enough.
Never give B-complex / thiamine (B1) while amprolium is being given — amprolium works by blocking thiamine; B1 in the water cancels the treatment.
Repeat a short (3-5 day) vitamin course only on a trigger: vaccination, antibiotic/anticoccidial/deworming treatment, transport, heat stress, or visible deficiency.
Fat-soluble vitamins (A, D, E, K) accumulate — continuous daily supplementation long-term is not required and can be harmful.
Sources: TNAU Agritech (growing chicks — vitamins/antibiotics 3-5 days); poultry liver-tonic product labels (5 days); PoultryDVM amprolium monograph (thiamine interaction).