Table 1. Descriptive statistics for piglet behaviour during the backtest.

	all piglets (n = 88)		piglets in analysis (n = 30)
	mean	sd	mean	sd
struggles (n)	2.71	1.15	2.9	1.12
struggling duration (s)	24.88	12.58	23.07	11.7
latency to struggle (s)	4.3	9.2	3.1	4.3
piglet weight (g)	1830	450	1870	430
maximum resistance force (maximum weight / piglet weight)	1.46	0.16	1.47	0.18
vocalizations (n)	50.3	21.6	56.7	20.1
screams (n)	20.5	18.6	21.9	16.8
grunts (n)	29.8	15.1	34.8	12.9
screams / s—relaxed	0.10	0.17	0.09	0.12
screams / s–struggling	0.67	0.43	0.76	0.32
grunts / s–relaxed	0.35	0.29	0.51	0.32
grunts / s struggling	0.81	0.61	0.78	0.45