Table 1.
Composition of basal diets (as-fed basis)
| Item | Phase 11 | Phase 22 | Phase 33 | Phase 44 | Phase 55 | Phase 66 |
|---|---|---|---|---|---|---|
| Feedstuff, % | ||||||
| Corn, yellow dent | 35.05 | 43.60 | 59.65 | 68.90 | 76.40 | 78.60 |
| Soybean meal, dehulled | 22.00 | 29.00 | 34.00 | 26.00 | 19.00 | 17.00 |
| Dried whey | 27.50 | 17.50 | 0.00 | 0.00 | 0.00 | 0.00 |
| Fish meal | 4.50 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| Animal plasma | 4.00 | 3.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| Animal fat | 2.00 | 1.50 | 1.00 | 1.00 | 1.00 | 1.00 |
| Limestone | 0.70 | 0.70 | 0.70 | 0.75 | 0.75 | 0.60 |
| Dicalcium phosphate | 0.40 | 1.50 | 1.30 | 1.10 | 0.90 | 0.85 |
| Sodium chloride | 0.45 | 0.35 | 0.25 | 0.15 | 0.15 | 0.15 |
| Vitamin–mineral premix7 | 2.00 | 1.50 | 2.00 | 1.00 | 0.70 | 0.70 |
| Zinc oxide | 0.30 | 0.25 | 0.00 | 0.00 | 0.00 | 0.00 |
| Supplement8 | 1.10 | 1.10 | 1.10 | 1.10 | 1.10 | 1.10 |
| Calculated composition | ||||||
| Dry matter, % | 91.14 | 90.66 | 89.92 | 89.70 | 89.58 | 89.53 |
| Metabolizable energy, kcal/kg | 3,300 | 3,289 | 3,310 | 3,355 | 3,375 | 3,382 |
| Crude protein, % | 23.03 | 22.15 | 21.19 | 18.16 | 15.46 | 14.69 |
| SID9 Lys, % | 1.31 | 1.20 | 1.03 | 0.83 | 0.66 | 0.61 |
| SID Met+Cys, % | 0.69 | 0.64 | 0.60 | 0.53 | 0.46 | 0.45 |
| SID Thr, % | 0.83 | 0.76 | 0.66 | 0.55 | 0.46 | 0.44 |
| SID Trp, % | 0.27 | 0.26 | 0.23 | 0.18 | 0.15 | 0.14 |
| Ca, % | 0.85 | 0.91 | 0.78 | 0.70 | 0.61 | 0.54 |
| STTD10 P, % | 0.51 | 0.52 | 0.38 | 0.33 | 0.28 | 0.26 |
1Phase 1 was 1 wk postweaning (21 to 28 d of age).
2Phase 2 was 2 wk after phase 1 (29 to 42 d of age).
3Phase 3 was 3 wk after phase 2 (43 to 63 d of age).
4Phase 4 was from the end of phase 3 to 121 d of age.
5Phase 5 was from 122 to 157 d of age.
6Phase 6 was from 157 to 171 d of age.
7Vitamin–mineral premix provided the following concentrations per kilogram of complete diet: 31.1 mg of manganese as manganous oxide, 50 mg of iron as iron sulfate, 69.2 mg of zinc as zinc oxide, 6.32 mg of copper as copper oxide, 0.48 mg of iodide as ethylenediamine dihydroiodide, 5,037.4 IU of vitamin A as vitamin A acetate, 550 IU of vitamin D3, 41.3 IU of vitamin E, 2.9 IU of vitamin K as menadione sodium bisulfite, 36.6 g of vitamin B12, 9.2 mg of riboflavin, 29.3 mg of D-pantothenic acid as calcium pantothenate, 36.6 mg of niacin, and 3,224 mg of choline as choline chloride.
8Four dietary treatments were formulated: a PC diet containing antibiotics and diets with 3 levels of BA at 0.00%, 0.50%, and 1.00% BA without antibiotics. In the PC diet, antibiotics were included at 100 mg/kg of chlortetracycline (equivalent to 450 mg/kg of Aureomycin 100) during phases 1 to 3 and 44 mg/kg of tylosin (equivalent to 200 mg/kg of Tylan 100) during phases 4 to 6. Both antibiotics and BA were supplemented by replacing a premix supplement in the basal diets. The premix supplement consisted of 50% corn and 50% animal fat. The total inclusion rate of antibiotics or BA plus the premix supplement was maintained at 1.1% across all dietary treatments, such that increasing the level of BA or antibiotics resulted in a proportional reduction in the amount of the premix supplement.
9Standardized ileal digestible. Coefficients were taken from NRC (2012).
10Standardized total tract digestible. Coefficients were taken from NRC (2012).