Manure samples were collected over a 10‐mo period from a feedlot with conventional pens and pens in which about one‐half the surface was covered with concrete. Samples were collected from the front, middle, and rear of each pen for each sampling period.The average percentages of 139 samples on a dry matter basis were: dry matter, 58.5; ash, 37.0; total N, 2.32; neutral detergent fiber, 45.9; acid detergent fiber, 39.7; hemicellulose, 6.29; cellulose, 9.78; lignin, 7.67; and ADF insoluble ash, 25.3. Average pH was 7.09. The average percentages on a dry matter basis for 63 manure samples were: P, 0.54; K, 1.35; Ca, 1.88; and Na, 0.51.Samples collected from concrete surfaces were 12.2% lower in ash because of less mising with soil. Effects of residence time of manure in the feedlot did not have a predictable effect upon composition because of the mixed influence of temperature, feedlot rations, and depth of the manure pack.