The density profile and cholesterol concentration of serum lipoproteins in domestic and laboratory animals.

1. By means of density gradient ultracentrifugation, the density profile of the serum lipoproteins was studied in 14 species of domestic and laboratory animals: the pig, chicken, rhesus monkey, rabbit, dog, horse, sheep, cat, mouse, goat, cow, guinea-pig, trout and rat. 2. The concentration of cholesterol in whole serum and the lipoprotein fractions of these animal species was also determined. 3. There were large differences in the density profile of the serum lipoproteins among the various animals studied and the results indicate that the density limits employed for human serum lipoproteins are not directly applicable to the lipoproteins of animals. 4. In most of the animals studied, three major lipoprotein fractions could be observed as in man. 5. However, such a clear pattern was not found in the cow, rat and guinea-pig. 6. In the animals studied, with the exception of the pig and the guinea-pig, most of the cholesterol in the serum was carried in the high density lipoprotein fraction.