Digestive System > Digestive Physiology of Herbivores

Digestive Anatomy and Function of Camelids

Camelids are a group of herbivores that include dromedary and Bactrian camels, alpacas, llamas, vicuñas, and guanacos. Their digestive anatomy is similar to, but clearly distinct from classical ruminants such as cattle, sheep and goats. These anatomic differences have led to camelids often being referred to as "pseudoruminants" and the forestomaches are described as compartments C-1, C-2 and C-3. The C-1 compartment is by far the largest and partitioned anatomically and functionally into cranial and caudal sacs.

Instead of having large papillae that extend into the lumen of the rumen of ruminants, camelids have two types of structures to extend into compartments C-1 and C-2 and serve to facilitate absorption of volatile fatty acids, water and electrolytes. These structures are called glandular saccules in C-1 glandular cells in C-2. The epithelium of the glandular saccules and glandular cells is simple columnar, in contrast to stratified squamous epithelium in the non-saccular regions of C-1.

The C-3 compartment is elongated and tubular and has two distinct regions. The cranial 80% of C-3 is lined with folds having glandular epithelium similar to what is seen in the saccules of C-1 and this region is highly absorptive. The terminal roughly 20% of C-3 is lined with gastric glands that secrete hydrochloric acid and proteases and functions the true stomach of camelids.

The following image shows the forestomachs of an alpaca, including compartments C-1, C-2 and C-3:

The same digestive tract is shown in the following image after incising the compartments, and the difference in mucosal structure of the cranial folds and caudal gastric gland structure of C-3 can readily be observed:

Similarly to what is seen in true ruminants, camelids display a complex pattern of motility within their forestomaches.

Herbivores: Introduction and Index

Updated April 26, 2021. Send comments to Richard.Bowen@colostate.edu