Measurement of Oro-Cecal Transit Time in LPS-Treated Pigs Fed High and Low Fiber Diets Using the Lactose- ¹³ C-Ureide Test in Breath and Saliva Samples

The lactose-¹³C-ureide (L¹³CU) test, used in humans to measure oro-cecal transit time (OCTT) in breath CO₂, was assessed for its suitability in pigs as a noninvasive alternative to intestinal cannulation. The OCTT was determined with the L¹³CU test in breath and saliva samples when pigs were fed low or high dietary fiber (DF) (low fiber, 2.8% DF; high fiber 6.5% DF) diets, and 24 h after an <i>i.m.</i> injection with either lipopolysaccharide (LPS) or NaCl. The OCTT measured in breath was longer in LF-LPS than in LF-NaCl and HF-LPS groups (3.4 vs 2.9 h; <i>p</i> < 0.05). Additionally, LPS prolonged the OCTT of pigs, and DF prevented this effect. 90 % of OCTT estimates measured in saliva and breath CO₂ did not differ. We conclude that the L¹³CU breath test is useful for determining OCTT in pigs; saliva is generally suitable as a sample matrix for OCTT, but its use requires further validation.