DIETARY-PROTEIN AND PLASMA CHOLESTEROL IN CHICKENS

The effects of the dietary protein source on plasma cholesterol in chickens consuming diets low in fat and without added cholesterol were studied in cockerels weighing approximately 1.5 kg. The diets contained lactalbumin, soybean protein, or egg white solids fed at 25 and 50% of the diet for 4 and 3 weeks respectively. Only minor differences in plasma lipids were observed. Lactalbumin fed birds had higher total and neutral lipids compared to birds fed soybean protein or egg white solids. Soybean protein feeding depressed plasma cholesterol compared to the other two proteins. After the initial feeding period, fasting caused cholesterol to increase slowly, regardless of the protein previously fed while refeeding the same proteins caused a rapid decrease. This reduction was only transitory since cholesterol returned to a peak concentration on the third day of refeeding. Thereafter, cholesterol declined gradually for 8 to 9 days to concentrations seen during continuous feeding. Ketone bodies during starvation and refeeding tended to parallel the changes in plasma cholesterol. The data indicate that alterations in plasma cholesterol caused by different dietary proteins are smaller in chickens than in rabbits. However, the changes in plasma cholesterol in both species seem to be similar during starvation and refeeding.