Table 1.
The influences of seasonal changes on the Dairy Herd Improvement (DHI) index in cows.
| Items | Spring | Summer | Autumn | Winter |
|---|---|---|---|---|
| somatic cell score | 4.5 ± 0.04 ab | 5.1 ± 0.46 a | 4.3 ± 0.20 ab | 3.8 ± 0.28 b |
| milk yield (kg/d) | 34.9 ± 0.14 a | 33.6 ± 0.19 b | 33.6 ± 0.33 b | 34.2 ± 0.22 ab |
| Protein (%) | 3.5 ± 0.02 a | 3.3 ± 0.03 b | 3.5 ± 0.02 a | 3.5 ± 0.05 a |
| Lactose (%) | 5.0 ± 0.02 b | 5.1 ± 0.02 a | 5.1 ± 0.01 a | 5.1 ± 0.07 a |
| fat (%) | 4.5 ± 0.17 | 4.4 ± 0.35 | 4.5 ± 0.01 | 4.4 ± 0.32 |
| dry matter (%) | 13.8 ± 0.13 a | 13.3 ± 0.17 b | 14.0 ± 0.02 a | 13.7 ± 0.23 ab |
| urea nitrogen (mg/dL) | 14.6 ± 1.98 | 14.3 ± 2.26 | 13.5 ± 1.11 | 16.6 ± 2.79 |
All data are represented by the mean ± standard error. n = 728 in the spring, n = 702 in the summer, n = 662 in the autumn and n = 686 in the winter. Different letters in the same rows are significant (p < 0.05).