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Table 4 Hazard ratios by parity or calving season

From: Epidemiological study to investigate the incidence and prevalence of clinical mastitis, peracute mastitis, metabolic disorders and peripartum disorders, on a dairy farm in a temperate zone in Japan

  Clinical mastitis Peracute mastitis Metabolic disorder Peripartum disorder
  Hazard ratio (95%CIa) Hazard ratio (95%CIa) Hazard ratio (95%CIa) Hazard ratio (95%CIa)
Parity
 1 Reference Reference Reference Reference
 2 1.66 (1.46–1.90) 2.99 (2.35–3.81) NSb NSb
 3 2.14 (1.88–2.44) 4.36 (3.44–5.52) 2.65 (1.80–3.89) 1.68 (1.24–2.29)
 4 2.03 (1.76–2.34) 4.48 (3.50–5.74) 2.79 (1.86–4.20) NSb
  ≥ 5 2.13 (1.86–2.45) 4.86 (3.81–6.19) 3.94 (2.68–5.78) NSb
Calving seasonc
 Spring NSb 0.85 (0.73–0.99) NSb NSb
 Summer 0.80 (0.69–0.93) 1.91 (1.42–2.58) 1.55 (1.18–2.04)
 Autumn 0.81 (0.70–0.94) NSb NSb
 Winter Reference Reference Reference
  1. a 95% CI: 95% confidence interval
  2. b NS: Not Significant
  3. c Calving season: Spring (March–May), Summer (June–August), Autumn (September–November), and Winter (December–February)