Table 2.
Descriptive statistics of explanatory variables in a study of herd-level risk factors for on-farm cow mortality in 6,898 Swedish dairy herds from September (Sep.) 2002 to August (Aug.) 2010.
| Variable | Category | n1 | No.1 with mortality, % | Mortality events per 100 cow-years |
|---|---|---|---|---|
| Calving interval, d | <389.3 | 31,017 | 52.5 | 5.3 |
| 389.3 to 403.5 | 30,618 | 53.4 | 5.6 | |
| 403.6 to 421.9 | 31,009 | 54.9 | 6.1 | |
| ≥422.0 | 31,015 | 56.6 | 7.0 | |
| Herd size, cow-years | 20 to 29.9 | 25,445 | 32.3 | 5.0 |
| 30 to 49.9 | 46,166 | 45.7 | 5.2 | |
| 50 to 99.9 | 38,505 | 66.3 | 5.8 | |
| ≥100 | 13,543 | 91.0 | 7.3 | |
| Milk yield, kg of ECM | <8,525 | 30,908 | 49.7 | 6.2 |
| 8,525 to 9,290 | 30,911 | 54.3 | 6.2 | |
| 9,291 to 9,980 | 30,912 | 55.1 | 5.8 | |
| ≥9,981 | 30,928 | 58.1 | 5.8 | |
| Predominant breed | Swedish Holstein | 32,987 | 60.1 | 6.8 |
| Swedish Red | 34,554 | 46.1 | 4.8 | |
| Mixed/other breeds2 | 56,118 | 56.0 | 6.1 | |
| Region3 | Södra Götaland (1) | 11,971 | 60.2 | 6.8 |
| Östra Götaland (2) | 39,184 | 52.1 | 6.2 | |
| Västra Götaland (3) | 38,365 | 53.6 | 5.7 | |
| Östra Svealand (4) | 9,859 | 52.1 | 5.4 | |
| Västra Svealand (5) | 7,087 | 51.9 | 5.5 | |
| Norrland (6) | 20,193 | 50.6 | 6.1 | |
| Season4 | Autumn-winter | 41,232 | 50.1 | 4.5 |
| Winter-spring | 41,257 | 55.7 | 5.1 | |
| Summer | 41,170 | 57.1 | 5.4 | |
| Year | Sep. 2002 to Aug. 2003 | 19,095 | 46.7 | 5.1 |
| Sep. 2003 to Aug. 2004 | 18,396 | 48.8 | 5.4 | |
| Sep. 2004 to Aug. 2005 | 17,343 | 52.9 | 6.0 | |
| Sep. 2005 to Aug. 2006 | 16,383 | 55.0 | 6.2 | |
| Sep. 2006 to Aug. 2007 | 14,742 | 56.7 | 6.3 | |
| Sep. 2007 to Aug. 2008 | 13,611 | 56.9 | 6.0 | |
| Sep. 2008 to Aug. 2009 | 12,630 | 60.8 | 6.5 | |
| Sep. 2009 to Aug. 2010 | 11,459 | 64.0 | 6.6 |
1
Number of herd-year-seasons.
2
Crossbreeds, Swedish Polled, and Swedish Jersey.
3
Numbers in parentheses refer to different regions identified in Figure 1.
4
Autumn-winter (September 1 to December 31), winter-spring (January 1 to April 30), and summer (May 1 to August 31).