Effect of group sizes
of 10, 20, 40 and 80 on productivity and behaviour in growing-finishing
pigs
S.A. Schmolke*1,2 and H.W.
Gonyou1
1Prairie Swine Centre,
Inc., Saskatoon, Canada; 2University of Saskatchewan, Saskatoon, Canada
The swine industry has shifted towards housing growing-finishing (G/F) pigs in larger group sizes while research on G/F pigs has generally focussed on smaller group sizes. The objective of this study was to quantify the effects of four group sizes (10, 20, 40 and 80 pigs) on productivity and behaviour. Each of the four replicates had two pens of 10 pigs, and one pen each of 20, 40 and 80 pigs. An equal number of males and females were housed in each pen. Initial bodyweight of pigs was 23.2 ± 4.8 kg. One wet/dry ad-libitum feeder was provided for every 10 pigs. Floor allowance was 0.88 m2 per pig. Pigs were weighed every 2 wk and feed measured daily to determine ADG, ADFI and to calculate feed efficiency. Injury scores were collected 48 hr post-regrouping on four body zones. During the initial 8 hr post-regrouping, the number and duration of fights were recorded via live continuous observations with a pig to observer ratio of 10 to 1. Time budgets were conducted twice within a replicate over a 24 hr period by instantaneous sampling at 5 min intervals for two out of every four hours. The frequency of eating, lying, standing, and sitting were recorded. Neither overall ADG nor ADFI was affected by group size (ADG = 0.861, 0.873, 0.854, and 0.845 kg/d, ADFI = 2.34, 2.42, 2.23 and 2.27 kg/d, for pens of 10, 20, 40 and 80, respectively; P > 0.10). Injury scores and post-regrouping aggression were similar among group sizes (P > 0.10). The percent of time spent at the feeder was greater in groups of 40 (8.2 %) than groups of 10 (7.0%) and 20 (7.2%; P < 0.05). Time spent lying, standing and sitting were similar among group sizes (P > 0.10). The percent of pigs removed from the study did not differ among group sizes (7.5, 6.2, 5.0 and 5.6% for pens of 10, 20, 40 and 80, respectively; P > 0.10). The results of this study indicate that housing G/F pigs in larger group sizes does not appear to be detrimental to productivity or behaviour.