Ambient temperature influences the choice made by pigs for certain types of floor

Enriching the environment of pigs is a way in which to improve welfare and it is used when legislation is formulated. An ethological study was carried out to determine the preference for one of three types of floor (litter: L; concrete: B; slatted : C), offered as free choice within the same pen. Sixteen groups of 6 growing pigs (70 kg) were used. The choices made by the pigs were analysed according to ambient temperature ; low (18°C) or high (27°C), in two experimental rooms.The major activities within a 24h period were resting (70% of time) and investigation (20%). The pigs preferred the litter flooring during the time spent investigating, whatever the ambient temperature (62% of total time of investigation). Pigs reared at 18°C preferred to rest on litter (71% of resting time vs. 12 % at 27°C), while when reared at 27°C they preferred the concrete or slatted floor (44% vs. 15% at 18°C). During resting, animals adopted significantly more frequently a ventral posture when cold (66% of resting time vs. 34% on the side) and lied-down on their sides when in warm conditions (55% vs. 44% in the ventral position). Pigs use separate areas for resting and for defaecation, and the location of these areas differ according to ambient temperature. The results indicate an interaction between floor type and temperature on the choices made by pigs. The thermal context (season and geographic location) should be integrated when European recommendations for housing are made.