Table 5.
Chemical analysis of experimental diets (Exp. 2; as-fed basis)1,2
| Analyzed Ca:P ratio: | 0.75:1 | 1.00:1 | 1.25:1 | 1.50:1 | 2.00:1 | |
|---|---|---|---|---|---|---|
| Item | STTD Ca:STTD P ratio2: | 0.95:1 | 1.18:1 | 1.40:1 | 1.62:1 | 2.07:1 |
| Calcium (Ca), % | ||||||
| Phase 1 | 0.47 | 0.53 | 0.70 | 0.84 | 0.97 | |
| Phase 2 | 0.33 | 0.38 | 0.56 | 0.69 | 0.87 | |
| Phase 3 | 0.30 | 0.41 | 0.54 | 0.62 | 0.87 | |
| Phase 4 | 0.27 | 0.36 | 0.50 | 0.48 | 0.81 | |
| Phosphorus (P), % | ||||||
| Phase 1 | 0.54 | 0.53 | 0.53 | 0.54 | 0.52 | |
| Phase 2 | 0.45 | 0.45 | 0.46 | 0.47 | 0.46 | |
| Phase 3 | 0.39 | 0.41 | 0.39 | 0.41 | 0.40 | |
| Phase 4 | 0.36 | 0.35 | 0.38 | 0.35 | 0.36 | |
| Ca:P ratio | ||||||
| Phase 1 | 0.87:1 | 1.00:1 | 1.32:1 | 1.56:1 | 1.87:1 | |
| Phase 2 | 0.73:1 | 0.84:1 | 1.22:1 | 1.47:1 | 1.89:1 | |
| Phase 3 | 0.77:1 | 1.00:1 | 1.38:1 | 1.51:1 | 2.18:1 | |
| Phase 4 | 0.75:1 | 1.03:1 | 1.32:1 | 1.37:1 | 2.25:1 |
1Representative samples of treatment diets were taken from 6 feeders per dietary treatment 3 d after the beginning and 3 d before the end of the phase and stored at −20 °C. After blending, subsamples were submitted to Ward Laboratories, Inc. (Kearney, NE) and Midwest Laboratories (Omaha, NE) for analyses in duplicate. Values represent the average across laboratories.
2Coefficients for standardized total tract digestibility (STTD) of P were obtained from NRC (2012), while values for STTD Ca in feed ingredients were obtained from Stein et al. (2016). These represent a weighted average of the ratio between STTD Ca:STTD P across treatments for the 4 dietary phases.