Preference for lamp or mat heat by piglets at cool and warm ambient temperatures with low to high drafts

Neonatal piglets (1.7 to 7.1 kg; 3.7 to 15.7 lb body weight) were allowed t o choose at will a heat source (lamp or mat) in a wind tunnel at cool (20 d egrees C; 68 degrees F) or warm (30 degrees C; 86 degrees F) air temperatur e coupled with various air velocities (0.05 to 0.45 m/s; 10 to 90 ft/min). The effects of original heat source in the farrowing crates on the choice o f the piglets were included. At the cool temperature (20 degrees C), piglet s from heat lamp-equipped farrowing crates showed preference for lamp heat at 1.7 kg (3.7 lb) and similar usage of mat and lamp at 2.4 to 5.3 kg (5.3 to 11.7 lb). Piglets up to 5.3 kg from the heat mat-equipped farrowing crat es generally did not show distinct preference for lamp or mat heat, except at the high draft condition (0.45 m/s; 90 ft/min) where preference for heat mat was exhibited. Piglets of 7.1 kg (15.6 lb) preferred mat independent o f the original heat source type. At the warm temperature (30 degrees C), pi glets of 2.6 to 5.3 kg (5.7 to 11.7 lb) showed almost equal usage of mat an d lamp independent of the original heat source type. Air temperature affect ed heat needs of the piglets. At 20 degrees C, total (i.e., lamp + mat) hea t usage (THU),by piglets of 1.7 to 2.4 kg (3.7 to 5.3 lb) averaged 98% of t he exposure time for all air velocities tested At 30 degrees C, THU ranged from 24% for 2.6 kg (5.7 lb) piglets to 5% for 4.4 kg (9.7 lb) piglets. THU declined substantially as piglets reached 3.4 kg (7.5 lb), especially at t he low air velocities. Piglets were more sensitive to drafts at the cool te mperature. Drafts up to 0.45 m/s (90 ft/min) had little effect on THU at th e warm temperature.