Table 3. Effects of a nursing sound stimulus on performance (mean ± SD) of lactating sows and suckling piglets

Variables	Treatment1)				p-value
	Control	T35	T40	T45
Sows
No. of sows	35	34	35	36
Parity	3.5 ± 2.6	3.4 ± 2.1	3.9 ± 1.9	3.5 ± 2.2	0.8032
Feed intake (kg/d)	6.4 ± 1.2	6.8 ± 0.7	6.7 ± 1.0	6.3 ± 1.3	0.5906
Back fat thickness (mm)
Before farrowing	26.3 ± 5.71	27.9 ± 2.6	26.2 ± 5.2	25.9 ± 3.3	0.7403
At farrowing	22.2 ± 5.54	23.8 ± 3.3	23.0 ± 6.1	21.3 ± 4.4	0.6041
Back fat thickness loss	4.0 ± 2.8	4.2 ± 2.1	3.2 ± 2.7	4.6 ± 1.7	0.2318
Piglets
Litter size (piglets/litter)
At day 0 postpartum2)	10.2 ± 1.0	10.3 ± 1.0	10.4 ± 0.9	10.4 ± 0.8	0.7986
At weaning	9.4 ± 1.3	9.7 ± 0.8	9.4 ± 1.0	9.4 ± 1.4	0.6600
Creep feed intake (g/litter/d)	766.1 ± 42.4	772.1 ± 39.5	772.0 ± 36.8	771.2 ± 42.4	0.9674
Average birth weight (kg)	1.4 ± 0.2	1.5 ± 0.3	1.5 ± 0.2	1.5 ± 0.2	0.2981
Average weaning weight (kg)	6.2 ± 0.8b	6.8 ± 0.5a	6.8 ± 0.7a	6.4 ± 0.7b	0.0004
Average daily gain (g)	237.7 ± 32.3b	252.7 ± 19.6a	255.1 ± 34.0a	233.5 ± 26.9b	0.0054

T35, T40, and T45 = 35, 40, and 45 min nursing sound stimulus interval, respectively.
After cross-fostering.
Different superscripts in the same row indicate a significant difference among treatments.