B12 and Non-Human Animals
There are many ways that mostly, or completely, herbivorous animals can potentially obtain B12 which are not available to vegans living in Western society.
Cows are ruminants, as are bison, buffalo, goats, antelopes, sheep, deer, and giraffes (1). Ruminants have a four-chambered stomach and a rich supply of bacteria in their rumen (the first chamber that their food enters) (1). Some of these bacteria produce B12 in amounts normally sufficient to meet their needs (2).
Non-human primates typically eat small amounts of eggs, insects, and small vertebrates and/or soil (3). Gorillas, possibly the closest to vegan of all the species closely related to humans, eat insects (3, 4) and sometimes feces (5).
Horses, elephants, zebras, rabbits, hares, and many rodents have large cecums in their digestive tracts, located between the small and large intestine (1) where bacterial fermentation takes place. Some sources say that all non-ruminant herbivores require some B12 fortification of their feeds (2), but at least one source says that bacteria in a horse's digestive tract are able to produce enough B12 if there is enough cobalt in the diet (6).
Many wild herbivores, such as elephants (7), inadvertently ingest soil on a regular basis. Hares, rabbits, and some rodents eat their fecal pellets, which provide an opportunity to obtain vitamins produced by bacteria in their digestive tracts (1).
The availability of B12 for animals who rely on bacterial synthesis of B12 (rather than getting it from animal foods) is dependent on cobalt levels in the soil. Citing an article from the Annals of the New York Academy of Science (1964;112:735-55), Crane et al. (8) point out that some soils in Australia, New Zealand, Britain, Canada, Ireland, Germany, Holland, Kenya, Poland, South Africa, Sweden, Russia, and the USA have insufficient cobalt for adequate B12 formation. They state, "This is a major concern of ours because vegans commonly seem to hold to the concept that all essential nutrients will be supported in foods from non-animal sources. They fail to realize that plants can grow readily in soil that is too low in cobalt for bacterial action to supply animals with sufficient B12."
2. Subcommittee on Vitamin Tolerance, Committee on Animal Nutrition, Board on Agriculture, National Research Council. Vitamin Tolerance of Animals. Washington, DC: National Academy Press; 1987.
3. Billings, Tom. Comparative Anatomy and Physiology Brought Up to Date. Part 2: Looking at Ape Diets--Myths, Realities, and Rationalizations. Accessed March 7, 2002.
4. Billings, Tom. Humanity's Evolutionary Prehistoric Diet and Ape Diets--continued, Part E: Correcting the vegetarian myths about ape diets. Accessed March 7, 2002.
5. Woodland Park Zoo, Seattle, WA. Frequently Asked Questions About the Gorillas. Accessed March 7, 2002.
6. TheHorse.com. Horse nutrition fact sheet. Accessed March 7, 2002.
7. University of Michigan. Animal Diversity website. Accessed March 7, 2002.