LPS-induced immune system stimulation alters urinary volatiles and behavior in growing pigs

Volatile compounds from body fluids and secretions may indicate the health status of individuals to other conspecifics. We sought to identify urinary volatiles that might act as biomarkers indicative of the health status of growing pigs. Immune system stimulation (ISS) was induced in pigs (N = 5) by intramuscular (IM) injection of bacterial lipopolysaccharide (LPS; 25 µg/kg BW). Urine samples were collected before (baseline) and after LPS treatment. The urinary headspace volatile compounds were identified using Solid-phase microextraction (SPME) coupled with GC-MS. Pig eye temperatures was measured using an infrared imaging technique, and behaviours (i.e. standing, feeding, drinking, moving, lying, sitting and active) were video-recorded and quantified 24 h before and after ISS. Data were analysed using mixed model ANOVA examining periods before and after LPS administration with pigs serving as their own control. Pig eye/body temperature increased post-ISS (at 6 h, P = 0.03) a