Table 2 : Estimates of climatic factors, other fixed effects and random effect variance included in the final models1
for the probability of a sow having stillborn piglets and for the number of stillborn piglets2 during the hot
and humid season (June to September).


Hot and humid s.eason Probability of a sow having
stillborn piglets
Number of stillborn piglets

Fixed effects (factors)3 and variance Estimate (+SE) P-value Estimate (+SE) P-value

Intercept -0.4213 (0.0392) <0.01  0.5121 (0.0125) <0.01
Maximum temperature (HT)  0.0014 (0.0041) 0.73  0.0050 (0.0011) <0.01
Relative humidity (RH)  0.0024 (0.0011) 0.02  0.0011 (0.0005) 0.03

Parity groups (Parity)

Parities 3 to 5  0.3334 (0.0199) <0.01  0.0672 (0.0087) <0.01
Parity 6 or higher  0.9063 (0.0283) <0.01  0.2385 (0.0103) <0.01

HT x Parity

HT x Parities 3 to 5  0.0152 (0.0043) <0.01 -- --
HT x Parity 6 or higher  0.0217 (0.0061) <0.01 -- --
Total number of pigs born (TPB)  0.2317 (0.0054) <0.01  0.0549 (0.0023) <0.01
TPB-squared  0.0092 (0.0011) <0.01  0.0033 (0.0002) <0.01
TPB-cubed -0.0003 (0.0001) <0.01 -- --
RH x TPB  0.0006 (0.0003) 0.03  0.0003 (0.0001) 0.04

Parity x TPB

Parities 3 to 5 x TPB  0.0172 (0.0062) <0.01  0.0106 (0.0030) <0.01
Parity 6 or higher x TPB  0.0452 (0.0086) <0.01  0.0208 (0.0034) <0.01

Parity x TPB-squared

Parities 3 to 5 x TPB-squared -0.0038 (0.0013) <0.01 -- --
Parity 6 or higher x TPB-squared -0.0069 (0.0018) <0.01 -- --
Intercept variance at herd level  0.1157 (0.0180) --  0.0070 (0.0013) --
Intercept variance at sow level  0.1156 (0.0188) -- -- --
Intraclass correlation coefficient (ICC;
records within the same herd), %
 3.3 --  1.2 --
ICC (records within the same sow), %  6.6 -- -- --

1Logistic regression and Poisson regression models were used respectively for the probability of a sow having stillborn
piglets and for the number of stillborn piglets.
2Omitted data were records of sows with no stillborn piglets.
3Reference category was the parities 1 and 2 sow group.

Koketsu et al.Veterinary Medicine and Animal Sciences  2016 4:3DOI : 10.7243/2054-3425-4-3