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

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

	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

ISSN: 2055-5660