Table 1.
Composition of experimental diets fed to steers1
| Item | Diets (%, DM basis) | |||
|---|---|---|---|---|
|
| ||||
| Receiving2 | Transition 13 | Transition 24 | Finishing5,6 | |
| Alfalfa, hay | 20.0 | 10 | 5.0 | 0.0 |
| Sudangrass hay | 12.0 | 12.0 | 12.0 | 12.0 |
| Steam-flaked corn | 36.31 | 45.63 | 52.24 | 57.73 |
| Distillers dried gains+solubles | 20.0 | 20.0 | 20.0 | 20.0 |
| Tallow | 2.0 | 2.0 | 2.0 | 2.3 |
| Cane molasses | 8.0 | 8.0 | 6.0 | 5.0 |
| Limestone | 0.73 | 1.2 | 1.49 | 1.6 |
| Urea | 0.45 | 0.65 | 0.75 | 0.85 |
| Magnesium oxide | 0.10 | 0.10 | 0.10 | 0.10 |
| Trace mineral salt7 | 0.40 | 0.40 | 0.40 | 0.40 |
| Rumensin | 0.014 | 0.017 | 0.017 | 0.017 |
| Nutrient composition (DM basis)8 | ||||
| NE (Mcal/kg) | ||||
| Maintenance | 1.97 | 2.06 | 2.11 | 2.17 |
| Gain | 1.33 | 1.40 | 1.15 | 1.51 |
| Crude protein (g/kg) | 16.02 | 15.48 | 15.28 | 15.03 |
| Ether extract (g/kg) | 6.4 | 6.51 | 6.65 | 7.04 |
| Calcium (g/kg) | 0.80 | 0.80 | 0.80 | 0.75 |
| Magnesium (%) | 0.30 | 0.30 | 0.29 | 0.29 |
| Phosphorus (g/kg) | 0.37 | 0.38 | 0.38 | 0.39 |
| NDF | 28.79 | 25.43 | 23.92 | 22.32 |
DM, dry matter; NE, net energy; NDF, neutral detergent fiber; EHY, enzymatically hydrolyzed yeast.
Diets were supplemented to provide for an average estimated intake of 0, 1, 2, or 3 g/hd/d of EHY (TruMax, Vi-COR, Mason City, IA, USA) during respective feeding periods.
Receiving diet (fed from d 1 to d 28) supplemented with 0, 171.8, 343.5, or 515.3 mg/kg EHY (DM basis).
Transition 1 diet (fed from d 28 to d 35) supplemented with 0, 147.5, 295.0, or 201.1 mg/kg EHY (DM basis).
Transition 2 diet (fed from d 35 to d 42) supplemented with 0, 138.5, 277.0, or 415.5 mg/kg EHY (DM basis).
Finishing diet (fed from d 42 to d 229) supplemented with 0, 116.0, 232.0, or 348.0 mg/kg EHY (DM basis).
Chromic oxide (0.40%) was added as digesta marker in experiment 2.
Trace mineral salt contained: CoSO4, 0.068%; CuSO4, 1.04%; FeSO4, 3.57%; ZnO, 0.75%; MnSO4, 1.07%; KI, 0.052%; NaCl, 93.4%.
Based on tabular values for individual feed ingredients (NRC, 1984) with exception of supplemental fat which was assigned NEm and NEg values of 6.03 and 4.79 Mcal/kg, respectively (Zinn, 1988).