Fig. 4

AB. Two-way comparisons of pre-weaning piglet mortality risk for sows (probabilityof a sow having a piglet death: PWM) during early (0–1 days) and late lactation (9–28 days; N = 264,333 sows) between gestation length groups and either parity (A) or SB groups (B). Means and SEs were estimated in mixed-effects models. ^x–zDifferent superscripts within SB groups represent significant differences in means (P < 0.05). ^a–dDifferent superscripts within gestation length groups represent significant differences in means (P < 0.05)