Table 1.
Effects of eggshell temperature in week 2 and week 3 of incubation on tibia morphological characteristics at day 41 or 42 of age in male broiler chickens.
| Variable | Tibia weight (g) | Proximal tibia length (cm) | Lateral tibia cortex thickness (cm) | Femoral side proximal tibia head thickness (cm) | Metatarsal side proximal tibia head thickness (cm) | Robusticity index (cm/g) |
|---|---|---|---|---|---|---|
| EST week 2 | ||||||
| 37.8°C | 16.71b | 13.55 | 1.25b | 3.22 | 3.02b | 0.82a |
| 38.9°C | 17.39a | 13.60 | 1.29a | 3.25 | 3.07a | 0.78b |
| SEM | 0.11 | 0.12 | 0.02 | 0.01 | 0.02 | 0.01 |
| EST week 3 | ||||||
| 36.7°C | 17.08 | 13.58 | 1.26 | 3.21 | 3.03 | 0.79 |
| 37.8°C | 17.03 | 13.57 | 1.28 | 3.25 | 3.06 | 0.80 |
| SEM | 0.11 | 0.12 | 0.02 | 0.01 | 0.02 | 0.01 |
| EST week 2 × week 3 | ||||||
| 37.8 × 36.7°C | 16.85 | 13.70 | 1.26 | 3.23 | 3.03 | 0.82 |
| 37.8 × 37.8°C | 16.58 | 13.40 | 1.24 | 3.21 | 3.02 | 0.81 |
| 38.9 × 36.7°C | 17.31 | 13.46 | 1.28 | 3.21 | 3.04 | 0.77 |
| 38.9 × 37.8°C | 17.47 | 13.74 | 1.31 | 3.29 | 3.09 | 0.79 |
| SEM | 0.15 | 0.17 | 0.02 | 0.02 | 0.02 | 0.01 |
| P-values | ||||||
| EST week 2 | <0.001 | 0.76 | 0.05 | 0.06 | 0.05 | <0.001 |
| EST week 3 | 0.71 | 0.96 | 0.57 | 0.11 | 0.25 | 0.54 |
| EST week 2 × week 3 | 0.16 | 0.10 | 0.26 | 0.06 | 0.15 | 0.16 |
a, bValues within a column and factor lacking a common superscript differ (P ≤ 0.05).
Abbreviations: EST, eggshell temperature.