Table 3 Comparisons of pre-weaning piglet mortality risk for sows (probabilities of a sow having a piglet death) during early (0–1 days), mid- (2–8 days) and late (9–28 days) lactation between parity, farrowing season, piglets born alive, gestation length and stillborn piglets groups¹

Parity

 1

55,635

34.3 (1.60)^b

25.5 (2.53)^a

14.5 (1.91)^a

 2–4

123,314

35.4 (1.72)^ab

25.7 (2.34)^a

12.7 (1.74)^b

 5 or higher

85,384

36.4 (1.74)^a

21.3 (2.20)^b

10.3 (1.45)^c

Farrowing season

 Jan.–Mar

64,584

35.5 (1.97) ^ab

22.3 (2.36)^b

12.1 (1.72)

 Apr.–Jun

64,264

35.2 (1.58) ^ab

24.0 (2.40)^ab

12.4 (1.71)

 Jul.–Sept

68,990

34.0 (1.54) ^b

25.5 (2.40)^a

13.3 (1.84)

 Oct.–Dec

66,495

36.8 (1.88) ^a

24.7 (2.32)^a

11.9 (1.54)

Piglets born alive

 11 or less pigs

69,232

28.1 (1.52)^c

21.5 (2.14)^c

12.2 (1.65)

 12–15 pigs

95,371

35.0 (1.61)^b

23.6 (2.21)^b

12.3 (1.63)

 16 or more pigs

99,730

43.9 (1.92)^a

27.5 (2.80)^a

12.8 (1.71)

Stillborn piglets

 0 pigs

127,524

31.5 (1.48)^d

22.0 (2.09)^d

12.0 (1.59)^b

 1 pig

65,185

33.0 (1.62)^c

22.8 (2.20)^c

11.9 (1.60)^b

 2 pigs

38,494

37.2 (1.73)^b

24.5 (2.36)^b

12.9 (1.71)^a

 3 or more pigs

33,130

39.8 (1.98)^a

27.2 (2.60)^a

12.9 (1.74)^a

Gestation length, days

 110–113 days

37,877

39.3 (1.93)^a

28.2 (2.63)^a

13.4 (1.81)^a

 114–116 days

187,339

35.2 (1.68)^b

23.1 (2.24)^b

12.0 (1.61)^b

 117–120 days

39,117

31.8 (1.49)^c

21.4 (2.06)^c

11.9 (1.57)^b