Failure of dietary-casein-induced acidosis to explain the hypercholesterolemia of casein-fed rabbits.

The partial replacement of casein by a mixture of gelatin, fish protein and soy protein in cholesterol-free semipurified diets of rabbits reduced the hypercholesterolemic response. The partial replacement of casein by the protein mixture also increased the feed intake and alleviated or reversed the weight loss observed from the casein diet. The data indicate that casein alone is not an ideal protein source for rabbits probably because of the imbalance of the amino acid composition. When KCl in the semipurified diets was replaced by KHCO3, a higher feed intake and a better growth were obtained, irrespective of the protein source in the diet. In addition, the feeding of semipurified diets containing KCl resulted in acidosis, which could be prevented by its replacement with KHCO3. A semipurified diet containing casein and KCl produced a more severe acidosis and higher serum cholesterol levels than the diet containing the protein mixture. Nevertheless, the correction of the acidosis by the replacement of KCl in the diet by KHCO3 did not lead to an abrogation of the casein-induced hypercholesterolemia.