Table 7.
Gestation length of Holstein cows with different parities
| Variables | Parity 11) | Parity 2 | Parity 3 | Parity 4 | Parity 5 | Parity 6 | Parity 7 | Parity 8 |
|---|---|---|---|---|---|---|---|---|
| Number of cows | 70 | 51 | 43 | 28 | 14 | 8 | 6 | 3 |
| Gestation length | ||||||||
| Mean (d) | 275.1±6.5 | 277.8±6.28 | 276.8±5.4 | 279.1±6.4 | 275.4±6.2 | 277.4±4.0 | 278.2±5.0 | 280.7±2.9 |
| Min (d) | 252 | 263 | 260 | 270 | 262 | 273 | 271 | 279 |
| Max (d) | 294 | 297 | 289 | 304 | 283 | 285 | 286 | 284 |
1)
The mean age at the first service and age at first calving in Holstein heifers are 493.2 days and 813.5 days (27.1 months), respectively.