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Table 6 Comparisons between factors for severe repeat-breeder (SRB) risks per service

From: Characteristics and risk factors for severe repeat-breeder female pigs and their lifetime performance in commercial breeding herds

  Gilts and sows
Explanatory variables N SRB risk (99% CI)
Parity groups
 0 93,604 0.92 (0.67–1.26)a
 1 78,243 0.49 (0.35–0.68)b
 2–5 229,859 0.24 (0.17–0.34)c
6 or more 52,352 0.11 (0.07–0.18)d
First-served month group
 Jan.-Mar. 113,178 0.29 (0.21–0.42)b
 Apr.-Jun. 114,322 0.30 (0.21–0.44)b
 Jul.-Sep. 112,615 0.40 (0.27–0.56)a
 Oct.-Dec. 113,943 0.29 (0.20–0.41)b
Herd productivity groups
 Low-performing herds 65,565 1.30 (0.73–2.22)a
 Intermediate-performing herds 196,848 0.57 (0.37–0.85)b
 High-performing herds 191,645 0.11 (0.06–0.21)c
WMI groups1
 WMI 0–6 days 315,071 0.26 (0.19–0.39)b
 WMI 7–12 days 22,633 0.36 (0.23–0.57)a
 WMI 13 days or more 22,750 0.27 (0.15–0.42)ab
  1. CI confidence interval, WMI weaning-to-first-mating interval
  2. a-cMean values within a group with different letters are different (P < 0.05)
  3. 1The WMI groups were compared in the model containing sows only (N = 360,454)