Variable or Fixed Formulas

Reputable cat-food manufacturers only use surplus nutrients from foods produced for the human food sector. Other manufacturers may use products that have been deemed unfit for human consumption.

Whatever the texture of commercial food, the recipes follow either a fixed or a variable formula. Fixed formulas remain constant and form the "premium" or "super-premium" end of the market.

These are the most expensive foods, because in them the manufacturers always use the same ingredients, making no substitutions.

A variable formula product is not necessarily inferior, as long as the varying ingredients remain of high quality and nutritional value. Variable formula foods maintain the same energy value.