A comparative study of the anatomy of the omasum in domesticated ruminants

The structure of the omasum was compared in 10 water buffalo (Bubalus bubalis), 10 Shorthorn cattle (Bos indicus), 9 Merino sheep (Ovis aries) and 10 cross-bred goats (Capra hircus), and the functional significance of the differences is discussed. The weight of the omasum and area of the internal laminae appeared to be smaller in Brahman cattle than the buffalo and British cattle. When compared in relation to body weight, the omasums of caprid animals were smaller than those of bovids, by a factor of 0.33-0.67 but the omasums of goats were appreciably larger than sheep. The number of laminae ranged from 33 to 35 for the sheep and goats compared with 122 to 169 for the buffalo and cattle. It is suggested that the marked difference in structure of the omasum between the small and large ruminants may influence the food intake of these animals through the effects of this gut compartment on absorption of nutrients and passage of digesta.