ACID-BASE-BALANCE AFFECTS DIETARY CHOICE IN CATS

The effect of acid-base status on self-selection of dietary protein wa s examined in three groups of adult male cats fed 20% soybean-protein and lactalbumin diets formulated to produce acidic, neutral or alkalin e status. In two experiments, cats were offered a choice between the 2 0% protein diets or (1) the same diet with additional protein as casei n (49% total crude protein) or (2) the same diet with added soybean-pr otein and lactalbumin (43% crude protein). Casein contained 0.63 mmol H+/g and caused all three groups to avoid the high casein diets by day 4. The high soybean-protein-lactalbumin diets did not contain added a cid but would produce some extra acid upon catabolism of the sulfur-co ntaining amino acids. Again, all three groups avoided the high protein diets by day 4. In a third choice trial, cats adapted to three low pr otein diets containing appropriate electrolytes to cause neutrality, a cidemia or alkalemia, were offered a choice between: neutral vs. acidi c; acidic vs. neutral or basic vs. acidic. The cats chose the neutral, neutral and basic diet respectively, restoring or maintaining acid-ba se homeostasis for each situation. The diets producing acidosis lowere d serum sodium and potassium concentrations. We conclude that cats sel ect appropriate diets in an attempt to maintain acid-base homeostasis. (C) 1996 Academic Press Limited