The use of computed tomography for in vivo estimation of reticulo-rumen and omasum contents in Alpine goats

Precise in vivo measurement of reticulo-rumen content (volume and mass) is required for the study of digestive processes. Rumen-cannulated animals have been classically used for this purpose, and less invasive alternatives are currently investigated to meet the replacement, reduction, and refinement (3Rs) ethical considerations in animal science. The objective was to compare in vivo reticulo-rumen and omasum volumes assessed by computed tomography (CT) scan with postmortem measurement of their respective digesta masses in dairy goats. Twenty Alpine dairy goats were scanned by CT, and the volumes of the reticulo-rumen and omasum were measured by CT image postprocessing. Goats were slaughtered immediately after CT scan and the masses of reticulo-rumen and omasum digesta were measured. Simple linear regressions were performed between volumes measured in vivo by CT and the corresponding digesta wet masses measured postmortem. Reticulo-rumen and omasum volumes determined by CT were significantly and linearly regressed against the corresponding digesta masses measured postmortem (R² = 0.72 and 0.87, residual standard deviation = 1.18 and 0.06 kg, and residual coefficient of variation = 11% and 12%, n = 20 and 19, respectively). The use of CT is a promising noninvasive method to measure volume and estimate digesta masses of reticulo-rumen and omasum in small ruminants.