Table 6.
Least square means for growth performance, carcass characteristics, and bone mineralization of growing-finishing pigs fed increasing analyzed calcium to analyzed phosphorus (Ca:P) ratio from 26- to 127-kg body weight (BW) in Exp. 11
| Analyzed Ca:P ratio2: | 0.75:1 | 1.00:1 | 1.25:1 | 1.50:1 | 1.75:1 | 2.00:1 | SEM | P-value | ||
|---|---|---|---|---|---|---|---|---|---|---|
| Item3 | STTD Ca:STTD P4: | 0.96:1 | 1.30:1 | 1.65:1 | 1.98:1 | 2.32:1 | 2.67:1 | Linear | Quadratic | |
| Grower period (day 0 to 56) | ||||||||||
| ADG, g | 902 | 930 | 927 | 910 | 943 | 923 | 11.1 | 0.129 | 0.279 | |
| ADFI, g | 1,913 | 1,911 | 1,934 | 1,906 | 1,949 | 1,961 | 31.9 | 0.073 | 0.439 | |
| G:F, g/kg | 472 | 487 | 480 | 478 | 485 | 471 | 5.0 | 0.791 | 0.037 | |
| Finisher period (day 56 to 110) | ||||||||||
| ADG, g | 942 | 977 | 994 | 985 | 951 | 932 | 18.6 | 0.390 | 0.009 | |
| ADFI, g | 2,811 | 2,979 | 2,970 | 2,941 | 2,860 | 2,866 | 37.1 | 0.708 | 0.002 | |
| G:F, g/kg | 335 | 328 | 335 | 3,335 | 333 | 325 | 5.4 | 0.388 | 0.400 | |
| Overall period (day 0 to 110) | ||||||||||
| ADG, g | 923 | 955 | 961 | 949 | 950 | 929 | 10.4 | 0.953 | 0.005 | |
| ADFI, g | 2,338 | 2,408 | 2,419 | 2,396 | 2,382 | 2,383 | 28.8 | 0.483 | 0.028 | |
| G:F, g/kg | 395 | 397 | 398 | 396 | 399 | 390 | 3.9 | 0.479 | 0.116 | |
| BW, kg | ||||||||||
| Day 0 | 26.3 | 26.3 | 26.3 | 26.3 | 26.3 | 26.3 | 0.71 | 0.967 | 0.860 | |
| Day 56 | 77.1 | 78.6 | 78.6 | 77.6 | 79.2 | 78.1 | 1.14 | 0.262 | 0.203 | |
| Day 110 | 124.9 | 129.0 | 130.0 | 128.2 | 127.9 | 125.6 | 1.72 | 0.906 | 0.006 | |
| Carcass characteristics5 | ||||||||||
| HCW, kg | 93.0 | 95.9 | 96.2 | 94.6 | 94.4 | 92.7 | 1.18 | 0.298 | 0.003 | |
| Yield, % | 74.5 | 74.4 | 74.0 | 73.8 | 73.8 | 73.8 | 0.33 | 0.066 | 0.471 | |
| Backfat, mm6 | 16.8 | 16.3 | 16.8 | 16.9 | 16.3 | 16.5 | – 7 | 0.584 | 0.823 | |
| Fat-free lean, %6 | 56.8 | 56.7 | 56.9 | 57.1 | 57.3 | 57.0 | – 7 | 0.236 | 0.832 | |
| Loin depth, mm6 | 68.4 | 69.0 | 68.8 | 70.9 | 69.7 | 68.3 | – 7 | 0.597 | 0.067 | |
| Bone characteristics8 | ||||||||||
| Ash, %6,9 | 61.2 | 61.5 | 62.4 | 62.3 | 62.4 | 62.5 | 0.19 | <0.001 | 0.017 | |
1A total of 1,134 pigs (PIC 359 × 1050, initially 26.3 kg) were used in a 110-d growth trial with 27 pigs per pen and 7 pens per treatment.
2Treatments were formulated to be adequate in standardized total tract digestible phosphorus (STTD P) within phases, which corresponded to 0.38, 0.32, 0.29, and 0.26% STTD P for phases 1, 2, 3, and 4, respectively.
3ADG = average daily gain; ADFI = average daily feed intake; G:F = gain-to-feed ratio; HCW = hot carcass weight.
4Coefficients 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.
5Nine hundred and seven pigs were transported to a commercial packing plant for processing and data collection (Swift and Company, Worthington, MN).
6Adjusted for HCW.
7SEM for backfat were 0.31, 0.30, 0.29, 0.29, and 0.29; SEM for fat free lean were 0.30, 0.29, 0.28, 0.28, 0.28, and 0.28; SEM for loin depth were 0.84, 0.82, 0.81, 0.81, 0.80, and 0.81 for 0.75:1, 1.00:1, 1.25:1, 1.50:1, 1.75:1, and 2.00:1 analyzed total Ca:P, respectively.
8Eighty-four pigs (2 pigs per pen, 1 barrow/1 gilt) visually assumed to represent the mean live weight of the pen were subsampled and shipped to a separate processing facility for bone collection (Natural Foods Holdings, Inc., Sioux Center, IA). A total of 84 third metacarpals were autoclaved for 1 h. After cleaning, bones were placed in Soxhlets containing petroleum ether for 7 d as a means of removing water and fat. They were then dried at 105 °C for 7 d, and then ashed at 600 °C for 24 h.
9The 2-way interaction and the effect of gender were tested and no evidence for significant effects was observed.