Table 3.
Nitrogen balance in growing beef steers fed diets of varying F:C at ad libitum intake
| Treatment1 | P-value | |||||||
|---|---|---|---|---|---|---|---|---|
| Item | HF:C | IF:C | EF:C | LF:C | VLF:C | SEM2 | Linear | Quadratic |
| N intake, g/d | 146.1 | 163.1 | 174.7 | 160.4 | 170.7 | 8.84 | 0.01 | 0.06 |
| N excretion, g/d | ||||||||
| Feces | 67.7 | 73.7 | 80.8 | 64.1 | 58.4 | 4.13 | <0.01 | <0.01 |
| Urine | 65.9 | 80.3 | 83.0 | 82.7 | 83.7 | 5.56 | 0.01 | 0.09 |
| Total | 133.6 | 154.5 | 163.4 | 147.2 | 141.7 | 7.57 | 0.48 | <0.01 |
| N excretion, % of total N excretion | ||||||||
| Feces | 53.2 | 48.8 | 49.6 | 44.9 | 41.3 | 2.71 | <0.01 | 0.57 |
| Urine | 46.9 | 51.1 | 50.3 | 55.1 | 58.7 | 2.71 | <0.01 | 0.57 |
| N excretion, % of total N intake | ||||||||
| Feces | 46.5 | 45.8 | 46.5 | 40.2 | 34.3 | 1.65 | <0.01 | <0.01 |
| Urine | 45.5 | 48.7 | 48.1 | 52.4 | 50.2 | 4.04 | 0.27 | 0.76 |
| Apparent N digested, g/d | 78.3 | 89.5 | 93.9 | 96.4 | 112.2 | 6.17 | <0.01 | 0.62 |
| Apparent N digested, % of N intake | 53.6 | 54.8 | 53.7 | 60.1 | 65.7 | 1.63 | 0.03 | <0.01 |
| N retained, g/d | 12.3 | 9.6 | 10.3 | 14.2 | 28.0 | 7.04 | 0.09 | 0.11 |
1DRC replaced corn silage and alfalfa hay at 0% (HF:C), 22.5% (IF:C), 45% (EF:C), 67.5% (LF:C), and 83.8% (VLF:C) of dietary DM.
2Pooled standard error of the least-squares mean (n = 10 except in period 3 n = 9).