Table 3.
Diet composition for phases 1 to 4 diets (Exp. 2; as-fed basis)1
| Item | Phase 1 | Phase 2 | Phase 3 | Phase 4 |
|---|---|---|---|---|
| Ingredient, % | ||||
| Corn | 67.85–64.83 | 76.19–73.60 | 81.22–78.99 | 81.56–79.50 |
| Soybean meal, 46.5% CP | 29.91–30.13 | 21.74–21.92 | 16.83–16.99 | 16.77–16.92 |
| Beef tallow | 0.50–1.60 | 0.50–1.45 | 0.50–1.30 | 0.50–1.25 |
| Monocalcium phosphate, 21% P | 0.48 | 0.30 | 0.15 | – |
| Limestone | 0.23–1.94 | 0.28–1.73 | 0.31–1.58 | 0.32 – 1.48 |
| Sodium chloride | 0.35 | 0.35 | 0.35 | 0.35 |
| L-lysine HCl | 0.30 | 0.30 | 0.30 | 0.23 |
| DL-methionine | 0.09 | 0.06 | 0.04 | 0.01 |
| L-threonine | 0.10 | 0.09 | 0.10 | 0.08 |
| L-tryptophan | 0.01 | 0.01 | 0.02 | 0.01 |
| Phytase2 | 0.04 | 0.04 | 0.04 | 0.04 |
| Vitamin and trace mineral premix3 | 0.15 | 0.15 | 0.15 | 0.15 |
| Total | 100.00 | 100.00 | 100.00 | 100.00 |
| Calculated analysis | ||||
| Standardized ileal digestible amino acids, % | ||||
| Lysine | 1.15 | 0.95 | 0.83 | 0.77 |
| Isoleucine:lysine | 63 | 62 | 61 | 66 |
| Leucine:lysine | 132 | 140 | 146 | 158 |
| Methionine:lysine | 32 | 32 | 31 | 30 |
| Methionine and cysteine:lysine | 56 | 57 | 58 | 59 |
| Threonine:lysine | 62 | 63 | 65 | 67 |
| Tryptophan:lysine | 18.9 | 18.6 | 18.7 | 18.8 |
| Valine:lysine | 69 | 69 | 70 | 75 |
| Total lysine, % | 1.29 | 1.07 | 0.94 | 0.88 |
| Net energy, kcal/kg | 2,489 | 2,540 | 2,571 | 2,575 |
| Crude protein, % | 19.4 | 16.1 | 14.1 | 14.0 |
| Analyzed calcium, % | 0.37–0.97 | 0.31–0.82 | 0.27–0.72 | 0.25–0.66 |
| Total calcium with phytase, % | 0.51–1.11 | 0.45–0.96 | 0.42–0.86 | 0.39–0.80 |
| STTD Ca4 with phytase, % | 0.35–0.78 | 0.31–0.67 | 0.27–0.59 | 0.26–0.55 |
| Phosphorus, % | 0.49 | 0.41 | 0.36 | 0.33 |
| STTD P5 with phytase, % | 0.38 | 0.33 | 0.29 | 0.26 |
| Available phosphorus, % | 0.32 | 0.27 | 0.24 | 0.21 |
| Analyzed calcium:phosphorus | 0.75:1–2.00:1 | 0.75:1–2.00:1 | 0.75:1–2.00:1 | 0.75:1–2.00:1 |
| STTD Ca:STTD P | 0.93:1–2.07:1 | 0.94:1–2.06:1 | 0.95:1–2.06:1 | 0.98:1–2.09:1 |
1Treatments were formulated to 0.75:1, 1.00:1, 1.25:1, 1.50:1, and 2.00:1 analyzed calcium to analyzed phosphorus ratios across dietary phases. These represent a weighted average of 0.95:1, 1.18:1, 1.40:1, 162:1, and 2.07:1 STTD Ca:STTD P ratios. Treatments were achieved with the addition of limestone at the expense of corn. Beef tallow was added to balance net energy across treatments. Phase 1 diets were fed from day 0 to 25 (25.3- to 44.6-kg BW), phase 2 from day 26 to 58 (44.6- to 74.4-kg BW), phase 3 from day 59 to 87 (64.4- to 103.0-kg BW), and phase 4 from day 88 to 114 (103.0- to 126.6-kg BW).
2Phytase (Ronozyme HiPhos, DSM Nutritional Products, Parsippany, NJ) was included at 1,000 FYT/kg releasing an assumed 0.15% aP, 0.132% STTD P, 0.144% total Ca, and 0.096% STTD Ca.
3Provided per kg of premix: 8,818,490 IU vitamin A; 1,102,311 IU vitamin D; 35,273 IU vitamin E; 3,527.4 mg vitamin K; 30.9 mg vitamin B12; 39,683 mg niacin; 22,046 mg pantothenic acid; 6,614 mg riboflavin; 165 g Zn from Zn sulfate; 165 g Fe from iron sulfate; 40 g Mn from manganese oxide; 17 g Cu from copper sulfate; 0.3 g I from calcium iodate; 0.3 g Se from sodium selenite.
4STTD Ca = standardized total tract digestible calcium. The STTD Ca were determined based on the analyzed Ca in feed ingredients and the coefficients for STTD of Ca in feed ingredients from Stein et al. (2016). These values also include the 0.096% STTD Ca release by phytase.
5STTD P = standardized total tract digestible phosphorus. The STTD P were determined based on the analyzed P in feed ingredients and the coefficients for STTD of P from NRC (2012). These values also include the 0.132% STTD P release by phytase.