Table 1.
Alfalfa and grass hay nutrient compositions (DM basis)1,2,3
| Alfalfa hay4 | ||||
|---|---|---|---|---|
| Nutrient | Control | Med-Se | High-Se | Grass hay |
| DM, g/kg | 874 | 874 | 878 | 871 |
| CP, g/kg | 170 | 183 | 157 | 68 |
| ADF, g/kg | 377 | 386 | 373 | 441 |
| NDF, g/kg | 402 | 417 | 430 | 640 |
| Nonfiber carbohydrates, g/kg | 316 | 289 | 286 | 195 |
| Fat, g/kg | 13.7 | 12.4 | 12.0 | 5.4 |
| Ash, g/kg | 98.3 | 98.6 | 115.0 | 91.6 |
| TDN, g/kg | 600 | 596 | 564 | 538 |
| Calcium, g/kg | 13.3 | 13.1 | 13.4 | 4.7 |
| Phosphorus, g/kg | 2.4 | 2.6 | 2.5 | 1.9 |
| Magnesium, g/kg | 3.2 | 3.5 | 3.4 | 2.4 |
| Potassium, g/kg | 23.3 | 23.3 | 22.5 | 15.9 |
| Sodium, g/kg | 0.98 | 1.14 | 1.11 | 1.35 |
| Copper, mg/kg | 10 | 11 | 11 | 4 |
| Iron, mg/kg | 292 | 447 | 261 | 613 |
| Manganese, mg/kg | 39 | 48 | 41 | 239 |
| Zinc, mg/kg | 20 | 19 | 20 | 24 |
| Selenium, mg/kg | 0.34 | 2.42 | 5.17 | 0.36 |
1Alfalfa hay samples were submitted to Cumberland Analytical Services, Maugansville, MD, for routine nutrient analysis and to Utah Veterinary Diagnostic Laboratory, Logan, UT, for Se analysis.
2Alfalfa hay DM determination was completed at a temperature of 105°C for 12 to 14 h in a forced draft oven. Methods for CP (990.03), ADF (973.18), ash (942.05), and minerals (985.01) were performed according to the AOAC International (AOAC, 2000). The NDF was determined according to Van Soest et al. (1991). Soluble protein was determined according to Krishnamoorthy et al. (1982). Fat was calculated by difference.
3Alfalfa hay samples were prepared for Se analysis as described by Davis et al. (2012), and Se was determined using inductively coupled argon plasma emission spectroscopy (ELAN 6000; PerkinElmer Inc., Shelton, CT).
4Control cows were fed non-Se-fortified alfalfa hay as a major portion of the ration plus a mineral supplement containing 120 mg/kg Se (U.S. Food and Drug Administration, 2016) from sodium selenite. Med-Se cows were fed alfalfa hay harvested from a field fertilized with 45.0 g Se/ha as sodium selenate and fed a mineral supplement without added Se. High-Se cows were fed alfalfa hay harvested from fields fertilized with 89.9 g Se/ha as sodium selenate and fed a mineral supplement without added Se; both groups received mineral supplement without added Se.