Table 5.
Effects of heat stress and dietary betaine on intestinal morphology of yellow-feathered broilers *.
| Dietary Betaine Levels (mg/kg) | Temperature | Duodenum | Jejunum | Ileum | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Villus Height, μm | Crypt Depth, μm | VH:CD | Villus Height, μm | Crypt Depth, μm | VH:CD | Villus Height, μm | Crypt Depth, μm | VH:CD | ||
| After 5 Weeks Heat Stress | ||||||||||
| 0 | TN | 523 | 65 | 8.09 | 397 | 49 | 8.25 | 215 | 45 | 4.83 |
| 0 | HS | 415 | 68 | 6.14 | 335 | 46 | 7.28 | 204 | 42 | 4.99 |
| 500 | HS | 474 | 63 | 7.68 | 337 | 49 | 7.02 | 233 | 42 | 5.58 |
| 1000 | HS | 559 | 60 | 9.50 | 330 | 48 | 7.12 | 248 | 50 | 4.94 |
| 2000 | HS | 479 | 64 | 7.88 | 338 | 53 | 6.43 | 231 | 47 | 5.00 |
| SEM | 34.7 | 3.9 | 0.679 | 25.8 | 3.1 | 0.803 | 21.9 | 4.0 | 0.352 | |
| Contrast | p-value | |||||||||
| TN vs. HS | 0.039 | 0.599 | 0.057 | 0.102 | 0.511 | 0.403 | 0.728 | 0.605 | 0.745 | |
| Linear | 0.122 | 0.387 | 0.057 | 0.983 | 0.162 | 0.456 | 0.340 | 0.165 | 0.708 | |
| Quadratic | 0.084 | 0.253 | 0.056 | 0.918 | 0.706 | 0.773 | 0.299 | 0.586 | 0.483 | |
| After 10 Weeks Heat Stress | ||||||||||
| 0 | TN | 566 | 105 | 5.54 | 318 | 66 | 4.95 | 192 | 59 | 3.26 |
| 0 | HS | 480 | 106 | 4.78 | 212 | 68 | 3.27 | 177 | 58 | 3.16 |
| 500 | HS | 540 | 87 | 6.42 | 265 | 60 | 4.55 | 228 | 58 | 4.15 |
| 1000 | HS | 555 | 102 | 5.84 | 287 | 63 | 4.72 | 209 | 58 | 3.60 |
| 2000 | HS | 529 | 109 | 5.03 | 283 | 61 | 4.99 | 189 | 60 | 3.13 |
| SEM | 22.9 | 8.4 | 0.508 | 21.9 | 6.0 | 0.434 | 23.9 | 5.9 | 0.378 | |
| Contrast | p-value | |||||||||
| TN vs. HS | 0.036 | 0.975 | 0.370 | 0.003 | 0.781 | 0.028 | 0.664 | 0.885 | 0.850 | |
| Linear | 0.114 | 0.541 | 0.751 | 0.037 | 0.405 | 0.037 | 0.882 | 0.822 | 0.717 | |
| Quadratic | 0.046 | 0.155 | 0.033 | 0.232 | 0.640 | 0.347 | 0.179 | 0.898 | 0.080 | |
* VH:CD, villus height to crypt depth ratio; TN, thermoneutral zone; HS, heat stress; SEM, standard error of means; TN vs. HS, TN group vs. HS control (0 mg/kg betaine) group.