Abstract
This chapter discusses the effect of cobalt in the synthesis or production of vitamin B12 in cattle and sheep. Topics include: structure and function of vitamin B12, succinate-propionate exchange, methylation, clinical consequences of cobalt deprivation, fatty liver diseases, infertility and perinatal mortality, disease susceptibility, cobalt sources, cobalt availability and vitamin B12 synthesis, effect of cobalt intake, effect of energy and protein substrates, metabolism of vitamin B12, mucosal transport and cellular aspects, dysfunctions in propionate metabolism, dysfunction in methylation, abnormal lipid metabolism, cobalt requirements, effects of species, breed, physiological state and husbandry, vitamin B12 in milk, and prevention and control of cobalt deprivation.