Abstract
Total plasma cholesterol was measured on non-fasted White Leghorn males and females, maintained in floor pens and fed a standard all-mash ration. Environmental effects were reduced through use of 4 generations from a closed breeding flock, permitting simultaneous determinations on birds of varying age as well as repeated measurements over several years. The average total plasma cholesterol level of hens from 8 to 57 months old was 195 mg % and did not vary with age. The cholesterol level of males remained relatively constant at 139 mg % between 8 and 25 months, but by 35-38 months it had risen significantly to 155 mg %. At 45 months of age, a small group of males had a level of 209 mg %.