Variables | N | Positive (%) | Univariable analysis | Multivariable analysis | ||||
---|---|---|---|---|---|---|---|---|
 | p-value* | odds ratio (CI95%) | β | S.E. | odds ratio (CI95%) | p-value* | ||
Age (years) |  |  | < 0.001 |  |  |  |  | < 0.001 |
1.25 to ≤4 | 26,152 | 3.5% | – | – | – | – | – | – |
> 4 to ≤8 | 18,384 | 6.7% | < 0.001 | 2.20 (1.99–2.43) | 0.724 | 0.053 | 1.99 (1.81–2.19) | < 0.001 |
> 8 to 15.29 | 1115 | 7.1% | < 0.001 | 2.43 (1.86–3.17) | 0.728 | 0.137 | 1.98 (1.55–2.54) | < 0.001 |
Somatic cell count (×1000/ml) |  |  | < 0.001 |  |  |  |  | < 0.001 |
1.0 to ≤ .4 | 11,711 | 3.2% | – | – | – | – | – | – |
> 14 to ≤26 | 11,630 | 3.9% | 0.05 | 1.15 (0.99–1.34) | 0.058 | 0.078 | 1.05 (0.91–1.21) | 0.45 |
> 26 to ≤39 | 10,622 | 5.3% | < 0.001 | 1.65 (1.43–1.91) | 0.272 | 0.078 | 1.36 (1.18–1.56) | < 0.001 |
> 39 to 97 | 11,447 | 7.2% | < 0.001 | 2.33 (2.03–2.68) | 0.467 | 0.077 | 1.66 (1.44–1.90) | < 0.001 |
Number of lactation |  |  | < 0.001 |  |  |  |  |  |
0 to ≤1 | 14,072 | 3.3% | – | – |  |  |  |  |
> 1 to ≤2 | 15,521 | 4.4% | < 0.001 | 1.68 (1.47–1.92) |  |  |  |  |
> 2 to ≤3 | 8681 | 6.0% | < 0.001 | 2.36 (2.05–2.73) |  |  |  |  |
> 3 to 11 | 7378 | 7.4% | < 0.001 | 2.99 (2.58–3.46) |  |  |  |  |
Milk production (pounds) |  |  | < 0.001 |  |  |  |  | < 0.001 |
0 to ≤52 | 12,220 | 7.7% | – | – | – | – | – | – |
> 52 to ≤68 | 11,384 | 4.4% | < 0.001 | 0.53 (0.47–0.61) | − 0.507 | 0.066 | 0.66 (0.59–0.75) | < 0.001 |
> 68 to ≤86 | 11,465 | 3.7% | < 0.001 | 0.44 (0.38–0.51) | − 0.722 | 0.076 | 0.56 (0.49–0.65) | < 0.001 |
> 86 to 192 | 10,524 | 3.3% | < 0.001 | 0.35 (0.30–0.42) | −1.110 | 0.093 | 0.43 (0.36–0.51) | < 0.001 |
Milk fat (%) | Â | Â | 0.03 | Â | Â | Â | Â | Â |
0 to ≤3.5 | 12,549 | 4.4% | – | – |  |  |  |  |
> 3.5 to ≤3.9 | 9903 | 4.5% | 0.89 | 1.00 (0.88–1.15) |  |  |  |  |
> 3.9 to ≤4.5 | 12,657 | 4.7% | 0.98 | 1.00 (0.87–1.13) |  |  |  |  |
> 4.5 to 9.9 | 10,543 | 5.9% | 0.01 | 1.17 (1.03–1.34) |  |  |  |  |
Milk protein (%) |  |  | 0.001 |  |  |  |  | < 0.001 |
0 to ≤3.0 | 12,418 | 4.9% | – | – | – | – | – | – |
> 3.0 to ≤3.3 | 13,952 | 4.1% | 0.008 | 0.84 (0.73–0.95) | −0.262 | 0.072 | 0.76 (0.67–0.87) | < 0.001 |
> 3.3 to ≤3.5 | 8224 | 5.0% | 0.61 | 0.96 (0.83–1.11) | − 0.261 | 0.083 | 0.74 (0.64–0.85) | 0.001 |
> 3.5 to 7.4 | 11,058 | 5.7% | 0.28 | 1.07 (0.93–1.23) | −0.380 | 0.083 | 0.67 (0.58–0.77) | < 0.001 |
Milk urea nitrogen (mg/dl) | Â | Â | 0.17 | Â | Â | Â | Â | Â |
0 to ≤5 | 12,076 | 4.7% | – | – |  |  |  |  |
> 5 to ≤11 | 14,833 | 5.0% | 0.77 | 1.02 (0.87–1.19) |  |  |  |  |
> 11 to ≤13 | 8087 | 5.0% | 0.52 | 1.05 (0.88–1.26) |  |  |  |  |
> 13 to 81 | 10,656 | 4.7% | 0.26 | 0.90 (0.76–1.07) |  |  |  |  |
Previous-305-d mature equivalent (305ME)(Kg) |  |  | < 0.001 |  |  |  |  |  |
0 to ≤21,120 | 11,687 | 6.6% | – | – |  |  |  |  |
> 21,120 to ≤25,690 | 11,540 | 5.1% | < 0.001 | 0.69 (0.60–0.79) |  |  |  |  |
> 25,690 to ≤29,550 | 11,253 | 4.3% | < 0.001 | 0.55 (0.47–0.64) |  |  |  |  |
> 29,550 to 46,720 | 11,171 | 3.3% | < 0.001 | 0.42 (0.35–0.50) |  |  |  |  |
305-d mature equivalent (305ME)(Kg) |  |  | < 0.001 |  |  |  |  |  |
0 to ≤20,220 | 11,718 | 6.8% | – | – |  |  |  |  |
> 20,220 to ≤25,370 | 11,485 | 5.1% | < 0.001 | 0.65 (0.57–0.74) |  |  |  |  |
> 25,370 to ≤29,400 | 11,256 | 4.2% | < 0.001 | 0.53 (0.46–0.62) |  |  |  |  |
> 29,400 to 46,720 | 11,192 | 3.2% | < 0.001 | 0.39 (0.33–0.46) |  |  |  |  |
Lactation persistence (%) |  |  | < 0.001 |  |  |  |  |  |
1 to ≤100 | 14,022 | 6.1% | – | – |  |  |  |  |
> 100 to ≤108 | 9976 | 5.0% | < 0.001 | 0.79 (0.70–0.90) |  |  |  |  |
> 108 to ≤116 | 11,286 | 4.0% | < 0.001 | 0.60 (0.52–0.69) |  |  |  |  |
> 116 to ≤225 | 10,368 | 4.0% | < 0.001 | 0.58 (0.51–0.67) |  |  |  |  |
Days in milk |  |  | < 0.001 |  |  |  |  | < 0.001 |
< 30 | 3658 | 6.4% | – | – | – | – | – | – |
−31-60 | 3280 | 5.3% | 0.39 | 0.90 (0.72–1.13) | 0.007 | 0.120 | 1.00 (0.79–1.27) | 0.94 |
61–90 | 1950 | 3.1% | < 0.001 | 0.49 (0.35–0.68) | −0.580 | 0.169 | 0.55 (0.40–0.78) | < 0.001 |
91–120 | 1604 | 4.5% | 0.01 | 0.67 (0.48–0.92) | −0.283 | 0.167 | 0.75 (0.54–1.04) | 0.08 |
121–150 | 1351 | 4.3% | 0.01 | 0.63 (0.45–0.89) | −0.403 | 0.180 | 0.66 (0.46–0.95) | 0.02 |
151–180 | 1224 | 5.6% | 0.07 | 0.74 (0.53–1.03) | −0.243 | 0.173 | 0.78 (0.55–1.10) | 0.16 |
181–210 | 1862 | 5.0% | 0.22 | 0.83 (0.62–1.11) | −0.152 | 0.154 | 0.85 (0.63–1.16) | 0.32 |
211–240 | 3336 | 3.6% | < 0.001 | 0.61 (0.46–0.80) | −0.513 | 0.143 | 0.59 (0.45–0.79) | < 0.001 |
241–270 | 6743 | 3.6% | < 0.001 | 0.57 (0.45–0.73) | −0.615 | 0.124 | 0.54 (0.42–0.69) | < 0.001 |
271–300 | 6498 | 4.6% | 0.001 | 0.68 (0.54–0.85) | −0.558 | 0.124 | 0.57 (0.44–0.72) | < 0.001 |
> 301 | 14,146 | 5.7% | 0.12 | 0.85 (0.69–1.04) | −0.557 | 0.116 | 0.57 (0.45–0.71) | < 0.001 |
Season of cow’s birth |  |  | 0.07 |  |  |  |  |  |
Winter (Dec-Feb) | 12,339 | 5.3% | – | – |  |  |  |  |
Spring (Mar-May) | 11,100 | 5.0% | 0.16 | 0.91 (0.80–1.03) |  |  |  |  |
Summer (Jun-Aug) | 12,134 | 4.5% | 0.01 | 0.84 (0.74–0.96) |  |  |  |  |
Fall (Sep-Nov) | 10,079 | 4.7% | 0.05 | 0.88 (0.77–1.00) |  |  |  |  |