Correlations Between Body Surface and Rectal Temperature of Newly Weaned Sows.

There is interest in using body temperature changes in sows as an indicator of the onset of estrus. However, the optimum location to measure body temperature has not been established. The objective of this study was to evaluate the relationships between sow body surface temperature (SBST) measured at various locations and rectal temperature. The study involved 98 multiparous sows weaned in 6 groups between September and November. Sows were housed in individual stalls and were checked daily for standing reflex from day 3 to 7 post-weaning. Temperature measurements were taken daily for 10 days post-weaning [at 06:15 (feeding time), 07:00, 07:30 (heat checking time), 09:00, 11:00, 13:00, 15:00, 17:00, 19:00, 21:00, and 23:00]. Surface temperature was measured using a handheld thermal camera at 4 locations: outer ear, back of the head, vulva, and ham. Rectal temperature was measured using a clinical thermometer. The ambient temperature in the room was measured at the same times as the animal measurements were taken. The PROC CORR procedure of SAS was used to determine correlations between SBST, rectal temperature, and average room temperature at the time of each measurement (RMT). All correlations between SBST at the different measurement locations were strong and positive (P < 0.0001; Table 1) with r values ranging from 0.64 (between vulva and the outer ear) to 0.89 (between vulva and ham). However, correlations between SBST and rectal temperature were relatively weak (range r = 0.14 to 0.18; P < 0.0001). Rectal temperature was not correlated with RMT (r = 0.02; P = 0.12); correlations between RMT and SBST measurements were positive, with the strongest correlations being with the outer ear and the back of the head (r = 0.45 and 0.50, respectively; P < 0.0001). In conclusion, this study suggests strong relationships between body surface temperatures at different locations but relatively weak relationships between these measurements and rectal temperature. In addition, these results suggest room temperature has a greater influence on body surface temperature than on rectal temperature. [ABSTRACT FROM AUTHOR]