Pure muscle meat is very low in calcium and high in phosphorus, so months of plain chicken or fish can invert the calcium-phosphorus ratio and harm bones and kidneys.
Taurine, vitamins A and D, essential fatty acids, and trace minerals are unevenly distributed in household ingredients and need precise, recipe-based supplementation.
Organ ratios matter too: too little liver risks vitamin A deficiency while too much can cause toxicity, so the whole recipe must balance rather than pile up single items.
For long-term homemade feeding, use a recipe reviewed by a veterinary nutritionist and recheck body condition regularly; keep occasional toppers under ten percent of daily calories.