Determination of gastrointestinal passage rate using three different markers in laying hens

The titanium dioxide (TiO₂) marker technique is currently widely practiced as a method to evaluate gastrointestinal (GI) passage rate in poultry. However, this method requires sacrificing the animal to obtain digesta samples, is labour‐intensive and eliminates the possibility of follow‐up studies with the same individual. The aim of this study was to evaluate whether the radiographic methods barium‐impregnated polyethylene spheres (BIPS) and barium sulphate (BaSO₄) suspension are in agreement with the TiO₂ technique and can be used as an alternative method for GI passage rate determination in laying hens. Whole‐body radiographs were taken at different time points. Hens of group 3 (n = 55) were orally inoculated with 5 g of feed mixed with 0.15 g TiO₂, 5 hens per time point sacrificed, and whole gastrointestinal organs (crop, proventriculus, gizzard, small intestine and large intestine) were collected and analysed for TiO₂ content. The average marker passage rate of hens administered BaSO₄ was significantly faster than those administered BIPS (gizzard: 15.2 hr vs. 43.2 hr; small intestine: 15.2 hr vs. 38.4 hr, respectively). A greater percentage of BIPS remained in the crop at 0, 0.5, 2, 3 and 8 hr post‐inoculation (p.i.) and in the gizzard at 2, 24, 36 and 48 hr p.i. (all p < 0.05) compared to TiO₂. In conclusion, the evaluation of the GI transit time is feasible using BIPS, TiO₂ and BaSO₄. The evaluation of the GI transit time using BIPS and BaSO₄ needs further investigation.