Table 4.

Quartiles for sow and piglet characteristics associated with stillborn rate, experiment 2

Litter birth weight1, kg	<16.9	16.9 to 19.7	19.8 to 22.4	>22.4	SEM	P-value
Stillborn, %	5.9b	6.9ab	6.4ab	8.1a	0.51	0.050
Mean pig birth weight1, g	<1,100	1,100 to 1,240	1,250 to 1,390	>1,400	SEM	P-value
Stillborn, %	8.2a	7.5ab	6.4bc	5.4c	0.50	0.005
Sow back fat day 1131, mm	<11	11 to 13	14 to 16	>16	SEM	P-value
Stillborn, %	8.7a	7.2ab	6.8b	5.6b	0.57	0.004
Sow BW day 1132, kg	<244	244 to 261	262 to 279	>279	SEM	P-value
Stillborn, %	5.4b	6.9ab	7.4a	7.8a	0.50	0.027
Parity1	<3	3	4	>4	SEM	P-value
Stillborn, %	4.3c	5.5bc	6.8b	8.6a	0.55	<0.001
Sow farrowing assistance1,2	No	Yes			SEM	P-value
Stillborn, %	5.0	7.6			0.41	<0.001
Total born3, n	<14	14 to 16	17 to 18	>18	SEM	P-value
Stillborn, %	4.7c	6.1bc	6.9b	10.1a	0.50	<0.001
Birth order ranking3, %	<25	25 to 50	50 to 75	>75	SEM	P-value
Stillborn, %	1.8d	3.7c	8.0b	15.6a	0.46	<0.001

¹A total of 728 sows were categorized into quartiles within each response variable, with each quartile representing ~25% of sows in the study population.

²Sow farrowing assistance was recorded for each sow. Yes represents at least one pig was pulled from the sow, no represents that no piglets were assisted out. Means represent the stillborn rate within each category.

³A total of 11,575 piglets (10,758 live-born and 817 stillborn) were categorized into quartiles within each response variable, with each quartile representing ~25% of piglets in the study population.

^a–dMeans within a row not sharing a common superscript differ, P < 0.05.