(Sorry, rabbits...)

From http://www.rawfoodexplained.com/why-...tamin-b12.html

The serum B12 levels of rabbits rise when they are fed inorganic cobalt or hay and oats grown in soil containing normal amounts of cobalt. Hamsters fed inorganic cobalt and no B12 had relatively high tissue levels of B12 and seemed to be obtaining entirely adequate amounts of the vitamin.

The Cal-Berkeley researchers who conducted the hamster study reported their result to be "a new finding among the nonruminants." Prior to this finding, though, a Russian researcher had reported that the combination of iron, vitamin C and cobalt had a positive effect on B12 deficiency in humans.