Nutritional value of meat: the influence of nutrition and physical activity on vitamin B12 concentrations in ruminant tissues Isabelle Ortigues-Marty, Didier Micol, Sophie Prache, Dominique Dozias and Christiane L. GirardReprod. Nutr. Dev., 45 4 (2005) 453-467DOI: https://doi.org/10.1051/rnd:2005038