Comparing surface temperature locations with rectal temperature in neonatal piglets under production conditions

Abstract

Surface temperature recording has shown promise in older pigs and in piglets but only under controlled conditions. The aim of this experiment was to compare surface temperatures using an infrared thermal camera (pointer), verified by the maximum temperature from the thermal images extracted by an algorithm (MATLAB®R2020), at the base, tip of ear, or eye, with rectal temperature under production conditions. The influence of bodyweight (BWC1; ≤0.80 kg, BWC2; 0.81 kg to 1.10 kg and BWC3; >1.10 kg), time post-partum (0 and 24 h) and colostrum intake (CI1; <200 g and CI2, ≥200 g) were investigated. Ear tip pointer temperatures showed low correlations with rectal temperature (r < 0.39; P = 0.20). Both the ear base and eye had moderate correlations (r = 0.53 and 0.55, respectively; P < 0.001 for both) to rectal temperature, and high correlations between pointer and extracted values (r = 0.73 and 0.82, respectively; P < 0.001 for both). At birth, eye temperatures had a moderate correlation with rectal temperature. The extracted eye, but not rectal or ear base, temperatures were higher (P = 0.01) in piglets consuming greater amounts of colostrum. In contrast to research settings, production conditions are highly variable and increase the inaccuracy of the surface temperature recordings. Therefore, overall, surface temperatures were not appropriate for commercial application in neonatal piglets.