Table 5.
Effect of digestible P (g/kg) and Ca:digestible P ratio on bone traits in pigs on d 91.
| Item | Digestible P1 | Ca:Digestible P | ||||||
|---|---|---|---|---|---|---|---|---|
| P– | P+ | p-Value 2 | 2.2:1 | 2.5:1 | 2.8:1 | p-Value 2 | SEM | |
| N° | 36 | 48 | 24 | 36 | 24 | |||
| Metacarpus III and IV | ||||||||
| Weight, defatted (g DM) | 30.6 | 32.0 | n.s. | 30.8 | 31.6 | 31.6 | n.s. | 0.95 |
| Ash (g) | 16.9 | 18.3 | * | 17.3 | 17.7 | 17.9 | n.s. | 0.54 |
| Ash (g/kg DM) | 555y | 573x | *** | 561b | 559b | 570a | * | 4.1 |
| Ca (g/kg DM) | 207y | 218x | ** | 215 | 210 | 213 | n.s. | 3.3 |
| P (g/kg DM) | 98y | 102x | * | 101 | 99 | 100 | n.s. | 1.8 |
| Zn (mg/kg DM) | 114 | 118 | n.s. | 116 | 116 | 117 | n.s. | 4.2 |
| BMC (g) 3 | 17.1 | 18.6 | * | 17.3 | 18.0 | 18.2 | n.s. | 0.49 |
| Bone area (cm2) | 22.8 | 22.9 | n.s. | 22.7 | 23.2 | 22.8 | n.s. | 0.41 |
| BMD (g/cm2) 3 | 0.754 | 0.806 | *** | 0.763b | 0.779ab | 0.797a | ** | 0.014 |
| Metacarpus III | ||||||||
| Weight (g) | 22.0 | 23.1 | n.s. | 22.2 | 22.7 | 22.8 | n.s. | 0.56 |
| Volume (cm3) | 18.0 | 18.3 | n.s. | 18.0 | 18.4 | 18.1 | n.s. | 0.46 |
| Density (g/cm3) | 1.22y | 1.26x | * | 1.23b | 1.23b | 1.26a | * | 0.013 |
| BMC (g) 3 | 8.9 | 9.7 | * | 9.1 | 9.4 | 9.5 | n.s. | 0.26 |
| Bone area (cm2) | 11.6 | 11.7 | n.s. | 11.6 | 11.7 | 11.6 | n.s. | 0.21 |
| BMD (g/cm2) 3 | 0.773 | 0.827 | ** | 0.783b | 0.801ab | 0.816a | * | 0.014 |
| Metacarpus IV | ||||||||
| Mid-section area (mm2) 4 | 169 | 162 | n.s. | 168 | 165 | 164 | n.s. | 6.5 |
| Maximal load (N) | 1580y | 1766x | ** | 1624b | 1635ab | 1757a | * | 67.8 |
| BMC (g) 3 | 8.2 | 8.8 | * | 8.3 | 8.6 | 8.7 | n.s. | 0.25 |
| Bone area (cm2) | 11.3 | 11.2 | n.s. | 11.1 | 11.4 | 11.2 | n.s. | 0.21 |
| BMD (g/cm2) 3 | 0.734 | 0.785 | ** | 0.743b | 0.757ab | 0.778a | * | 0.015 |
| Front Foot | ||||||||
| BMC (g) 3 | 38.8y | 41.9x | * | 39.2 | 40.7 | 41.1 | + | 0.99 |
| Bone area (cm2) | 62.9 | 65.0 | n.s. | 63.6 | 64.4 | 63.8 | n.s. | 1.11 |
| BMD (g/cm2) 3 | 0.618y | 0.644x | * | 0.616b | 0.632ab | 0.644a | * | 0.010 |
1 P– = Formulated to contain 2.5 and 1.7 g digestible P/kg grower and finisher diets, respectively. P+ = Formulated to contain 3.0 and 2.4 g digestible P/kg grower and finisher diets, respectively. 2 *** p < 0.001; ** p < 0.01; * p < 0.05; n.s. (non-significant) P > 0.10; + P < 0.10; two-way interactions were not significant. Thus, only main effects are presented. For each main factor, values in the same row not followed by the same letter differ. 3 BMC = bone mineral content; BMD = bone mineral density measured by DXA 4 Mid-section area = π * (longest mid-shaft diameter/2)2.