Table 1.
Mean, standard deviation (STD) and range for herd parameters obtained from NDHRS from the year 2012 in 1194 dairy herds, included in a study of BRSV and BCoV as measured by bulk tank milk antibodies in the study area of Sogn og Fjordane and Møre og Romsdal county on the northwest coast of Norway.
| Variable | Mean |
Overall mean | STD | Range | |||
|---|---|---|---|---|---|---|---|
| BRSV+ | BRSV− | BCoV+ | BCoV− | ||||
| Herd size | 25.8 | 16.8 | 23.3 | 14.9 | 20.9 | 14.7 | 3.3–123.6 |
| Average milk production per cow-year, in kg | 7295 | 7161 | 7306 | 7012 | 7222 | 1123 | 2984–13682 |
| Mean somatic cell count in BTM | 122.8 | 116.0 | 121.3 | 113.0 | 119.1 | 40.4 | 24–273 |
| Mean distance to the 5 nearest herds, in km | 1.8 | 2.3 | 1.9 | 2.6 | 2.1 | 1.7 | 0.19–18.0 |
| Replacement rate | 41.9 | 42.2 | 42.9 | 40.0 | 42.0 | 16.9 | 0–128 (IQR: 31–51) |
| Herd disease incidence* | 94.0 | 91.4 | 95.2 | 86.0 | 93 | 66.9 | 0–500 |
| In-degree** | 2 | 2 | 2 | 1 | 2 | 9.7 | 0–181 |
*
Herd disease incidence per 100 cow-years (year 2012).
**
In-degree: median number of direct ingoing contacts through animal purchase over a period of almost five years.