Dietary protein level and experimental aortic atherosclerosis.

White Carneau pigeons were fed diets containing three levels of protein (compensated for by changes in the dextrin level); all other dietary constituents, including cholesterol, were at the same level, and these diets were fed for nine months, when the birds were killed and necropsied. Group A, which was fed the lowest level of dietary protein (10%), which is considerably less than that in Pigeon Chow Checkers, showed a high mortality rate (50%) and the survivors showed a significant loss in body weight. The birds in the other two groups, B and C (20 and 40% protein respectively) showed no significant changes in body weight during the experiment. When the mean serum uric acid values for the last four blood sampling periods, at two months intervals, in the last seven months of the experiment were compared with the values for A, only Group C showed a significant increase. There was no significant difference in serum total cholesterol concentrations, when compared in the same way. There were no significant changes in either the aorta atherosclerosis indices or the mean aorta cholesterol concentrations, determined after necropsy. If one compares the serum total cholesterol concentration for the groups of pigeons, of the blood samples drawn the day before they were killed, there were significant increases observed for Groups B and C. This work does not support the suggestion previously made that the dietary protein cholesterol interact in determining the concentration of aorta cholesterol and the atherosclerosis index in this breed of pigeon.