The Effects of Training on Kinematics in a Mixed Group of Grower Pigs Using Negative Reinforcement and Positive Punishment over a Week

The objective of this study was to investigate the amount training necessary for reliable data to be obtained. Thirty-one True Choice Genetics pigs (CG32 x EB5 (9 females, 7 males) and CG32 x EBX (8 females, 7 males) weighing 68 kg were used to determine changes in gait due to training. Pigs were individually walked across a 7.5 m pressure mat (GAIT4Dog®) every day on D1-D5 and then again on D8. Training was conducted using a sorting paddle as negative reinforcement (removing pressure) and positive punishment (adding pressure). Sessions were recorded on D1, D2, D4, and D8. Pigs walked across the mat for either 6 usable repetitions or for a maximum of 20 minutes. Stance time, swing time, stride length, percent stance, gait cycle, and velocity were determined for each day. All data were analyzed using SAS 9.4 PROC MIXED repeated measures model. There was a significant increase in velocity from D1 to D4 and a decrease on D8 (P < 0.001), which resulted in a decrease from D1 to D4 and an increase on D8 in swing time (P < 0.001), stance time (P < 0.001), cycle time (P < 0.001), and percent stance (P < 0.001). There were differences between females and males for self-selected velocity (P < 0.001), and stride length (P < 0.001). Females had a decreased cycle time (P < 0.001) and percent stance (P < 0.001). Differences between the EB5 and EBX sire lines were seen for rear swing (P < 0.001), front stance (P < 0.01), cycle time (front P < 0.02), and percent stance (front P < 0.01). Changes due to training reflect the loss of novelty to the mat due to repeat exposure. Differences due to sex and genetic line may be related to conformational differences.

	D1	D4	D8	Female	Male	EB5	EBX
Velocity (cm/s)	180.3	196.81	188.67	197.35	182.75	187.75	192.35
Swing (s) Front	0.23	0.22	0.22	0.23	0.22	0.23	0.23
Rear	0.26	0.25	0.25	0.25	0.25	0.26	0.25
Stance (s) Front	0.26	0.22	0.24	0.22	0.25	0.24	0.23
Rear	0.23	0.19	0.21	0.19	0.22	0.21	0.21
Stride Length (cm) Front	83.49	84.59	84.24	85.84	82.71	83.77	84.78
Rear	83.28	84.36	84.01	85.65	82.46	83.59	84.52
Percent Stance (%) Front	50.92	49.38	49.92	48.48	51.84	50.65	49.67
Rear	45.69	43.11	44.38	42.41	45.87	43.65	44.63

Least square means of gait parameters for days, sex and sire lines