A total of 450 pigs were used in two studies to examine the effects of group size and floor space on use of space and pig performance for pigs held in confinement on total concrete slats. In the first study, pigs showed similar weight gain, feed intake and feed efficiency when held in pens providing 0.74 m2 per pig and in group sizes of 10, 20 or 40 pigs per pen. Pig injury/morbidity rates were greatest for pigs held at 40 pigs per pen. Examination of pig postures every 30 min for a 24-h period allowed us to use published allometric equations to determine amount of floor space occupied by pigs and amount of floor space free or unoccupied. Free space perpig increased as group size increased. In the second performance trial, removal of 50% of the free or unused space resulted in no performance problem; however, removal of all the free space (or exactly meeting pig body space needs) resulted in reduced pig weight gain. These data support the idea, firstly, that space needs per pig decrease slightly as group size increases. Secondly, to avoid performance set-backs, pigs require some free space beyond their static space requirements (beyond their need for resting places for their bodies).
- Group size