PSII-5 - Temperature preference of nursery pigs housed in groups with mixed body weight

Abstract: Current recommendations for ambient temperatures for newly-weaned pigs are based on historical research carried out many years ago. Since that time, significant changes have occurred in the genotype of the pigs, as well as in management and housing conditions. The objective of this study was to establish the preferred temperature of groups of pigs, with typical variation in BW, over the first 4 wk after weaning (at 21 ± 1 d). The study involved 120 newly-weaned pigs housed in mixed-sex pens (barrows and gilts) of 20. Three temperature treatments were compared: 26°C vs. 30°C vs. 34°C; the 3 treatments were available to the pigs within each pen. The temperature treatments were created in 3 distinct zones of the pen using a heat lamp suspended over an insulated mat. Room temperature was set at 22°C for the duration of the study. Initial and final BW were 6.2 ± 0.9 kg and 15.3 ± 2.4 kg, respectively. Throughout the study period, the pigs had ad libitum access to nursery diets formulated to meet NRC (2012) requirements. Images of the pen area were captured every 15 min during the study period. The location (in the temperature treatment zones or other areas of the pen) and posture (lying, sitting, or standing) of every pig in the group were recorded from the images. The ambient temperature in the temperature treatment zones and other areas of the pen were recorded every 2 hr throughout the study period using a thermal camera. The preferred temperature was calculated by weighting the percentage of observations of pigs located within each temperature treatment zone and the other areas of the pen by the average temperature in each zone and area. The percentage of observations of pigs in the 26, 30, and 34°C temperature treatments areas were: Week 1 [10.5, 23.1, and 44.2% (SEM 10.70), respectively], Week 2 [7.8, 25.8, and 44.6% (SEM 5.00), respectively], Week 3 [7.6, 24.0, and 34.1% (SEM 4.89), respectively], and Week 4 [12.3, 21.2, and 26.8% (SEM 4.28), respectively]. The calculated preferred temperatures were 31.1, 31.7, 29.6, and 27.7°C for wk 1, 2, 3, and 4 post-weaning, respectively. The impact of housing nursery pigs at these temperatures on pig performance needs to be established.