Canadian scientists B. R. Street and H. W. Gonyou (Prairie Swine Centre), have examined how housing finishing pigs in two group sizes and at two floor space allocations can effect production, health, behavior, and physiological variables.

The studies, which were recently published in the Journal of Animal Science, looked at the effects of small (18 pigs) vs. large (108 pigs) group sizes provided 0.52 m2/ pig (crowded)or 0.78 m2/pig (uncrowded) of space on production, health, behavior, and physiological variables.

Eight, 7-8 week-long blocks, each involving 288 pigs, were completed. The average liveweight at the beginning of the study was 37.4 ± 0.26 kg. Overall, average daily gain (ADG) was 1.032 kg/day and 1.077 (±0.015) kg/day for crowded and uncrowded pigs, respectively (P = 0.018).

Differences between the space allowance treatments were most evident during the final week of study.

Pigs in the crowded groups spent less (P = 0.003) time eating over the eight-week study than did pigs in non-crowded groups. However, average daily feed intake (ADFI) did not differ (P = 0.34) between treatments. Overall, ADG of large-group pigs was 1.035 kg/d, whereas small group pigs gained 1.073 kg/d (±0.015; P = 0.039). Average daily gain differences between the group sizes were most evident during the first two weeks of the study.

Minimal Changes

The investifation found that over the entire study, large groups were less efficient (P = 0.005) than small groups. Although large-group pigs had poorer scores for lameness (P = 0.012) and leg scores (P = 0.02) throughout the eight-week period, morbidity levels did not differ (P = 0.32) between the group sizes. Minimal changes in postural behavior and feeding patterns were noted in large groups.

An interaction (P = 0.04) of group size and space allowance for lameness indicated that pigs housed in large groups at restricted space allowances were more susceptible to lameness. Although some behavioral variables, such as lying postures, suggested that pigs in large groups were able to use space more efficiently, overall productivity and health variables indicate that pigs in large and small groups were similarly affected by the crowding imposed in this study.

Broken-line analysis of ADG indicated no difference in the response to crowding by pigs in large and small groups. Little support was found for reducing space allowances for pigs in large groups.

References
B. R. Street and H. W. Gonyou. Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5A8; and Prairie Swine Centre Inc., Saskatoon, Saskatchewan, Canada S7H 5N9 J. Anim Sci. 2008. 86:982-991. doi:10.2527/jas.2007-0449

To view the article published in the Journal of Animal Science click here