Non-invasive measures of oral-rectal transit in young pigs

• We developed a non-invasive method to determine oral-rectal transit in pigs.
• There are differences in transit of fluid- and solid-phase markers.
• Plastic markers studies are useful to estimate transit times in young pigs.
• Our method can be correlated to oral-rectal transit studies performed in humans.

The gastrointestinal transit of markers in pigs has been well studied, but the methods and approaches are different from gastrointestinal studies performed in humans clinically.AimTo develop a non-invasive method of estimating oral-rectal transit times in young pigs.MethodsWe performed transit studies in 3 groups of 4 week-old, Large White female pigs. Group 1. Ten animals (5.7±0.34 kg (mean±SEM)) were fed blue-dyed grower feed and placed under video surveillance. Group 2a. Twenty-two animals (7.7±0.59 kg) from the same pig supplier were administered 18 4 mm-diameter radio-opaque plastic markers under light anaesthesia (5% isofluorane), and we took abdominal x-rays at 6, 30, 54 and 78 h. Group 2b. Eight pigs (9.2±0.48 kg) from a different supplier also underwent plastic marker transit studies.ResultsUsing blue dye (fluid transit), the median (25th, 75th percentiles) time to first incidence of blue-dyed stool was 13.2 (10.2, 18.1) h and to last blue stool was 24.1 (22.4, 40.3) h. Using plastic markers, markers were evacuated between 30 and 80+ hours with differences in stomach emptying between two groups of animals from different farms. Median oral-rectal transit times were 25.2 (17.8, 40.5) h and 48.9 (26.9, 68.3) h in the second and third groups (M-W test, P=0.04).ConclusionThere are differences in the transit of fluid- and solid-phase marker in pigs. Fluid-phase markers appear earlier than solid markers. Monitoring the evacuation of fluid-phase dye using video surveillance is difficult. Using plastic markers and x-rays to estimate the segmental and oral-rectal transit times in young pigs may be a useful method that can be correlated to oral-rectal transit studies performed in humans. The ability of pigs to hold solids in the stomach for extended times complicates transit studies. There are some differences in transit in pigs from different breeders.