SHADE-SEEKING AND LYING BEHAVIOR IN PIGS OF MIXED-SEX AND AGE, WITH ACCESS TO OUTSIDE PENS

Observations were made over a 2 month period (50 days) of the standing, lying and shade-seeking behaviour of boars, sows, growers and weaners with access to an outside pen. Some pigs sought shade between 15 and 20-degrees-C, and by 26-30-degrees-C nearly all the boars (88.3%), sows (87.3%) and growers (91.2%) were in the shade. However, only 65.4% of the weaners were in the shade. Above 35-degrees-C, the proportion of weaners seeking shade had increased to 85%. At the lower temperatures (15-20-degrees-C) most of the sows in the shade were lying down (84.7%), but only 13.3% of the boars, 54.8% of weaners and 67.6% of growers were lying in the shade. Above 35-degrees-C, almost all sows and boars in the shade were lying down (99.6% and 97.9%, respectively) and many of the growers (93.9%) and weaners (91.1%). The younger animals were more restless or lacked the experience to seek shade, either standing or lying down. The proportion of all pigs in the sun (standing or lying) in the morning (08:00-12:00 h) was negatively related to temperature (P<0.01) and there was no relation with time. In the afternoon (13:00-16:00 h), ambient temperature was not related to the proportion of pigs in the sun, however, time of day showed a weak correlation for boars, sows and weaners, but not for growers. In the morning (08:00-12:00 h) and afternoon (13:00-16:00 h), the proportion of animals standing was related to time rather than temperature. In the morning, the proportion standing decreased and in the afternoon increased with advancing time. If access to outdoors becomes an alternative pig husbandry system, consideration should be given to provision of shade in temperatures above 20-degrees-C.