Table 5.
Ultrastructural variables in calcified shell during formation in young (36 wk of age) and aged (70 wk of age) ducks.
| Time postoviposition | Eggshell calcification phases | Calcified shell ultrastructure1 | Young duck | Aged duck | P-value |
|---|---|---|---|---|---|
| 9.5 h | Initial | Mammillary knob density (/mm2) | 588 ± 25.6a | 524 ± 34.6b | 0.004 |
| 15.5 h | Growth | Mammillary knob width (μm) | 82.9 ± 7.51 | 91.3 ± 5.39 | 0.076 |
| Mammillary thickness (μm) | 99.4 ± 4.80 | 102 ± 9.24 | 0.636 | ||
| Effective thickness (μm) | 89.2 ± 7.07a | 59.3 ± 3.34b | <0.001 | ||
| 20.5 h | Terminal | Mammillary knob width (μm) | 87.3 ± 3.64 | 83.0 ± 4.90 | 0.118 |
| Mammillary thickness (μm) | 94.2 ± 11.4 | 91.8 ± 14.5 | 0.757 | ||
| Effective thickness (μm) | 215 ± 18.1b | 189 ± 16.4a | 0.026 | ||
| Total thickness (μm) | 309 ± 28.3 | 281 ± 29.4 | 0.120 | ||
| Mammillary layer (%) | 30.4 ± 1.45 | 32.6 ± 2.22 | 0.075 | ||
| Effective layer (%) | 69.6 ± 1.45 | 67.4 ± 2.22 | 0.075 |
a-b
Values within a row with no common superscripts differ significantly (P < 0.05)
1
Mean of 6 replicates (1 egg per replicate) per treatment.