90% of the worldwide B12 supplements produced are given to cows and other farmed animals. So, eating meat for B12 is actually less efficient than simply taking a supplement directly. You learn something new everyday - I try to.
Do carnivores need Vitamin B12 supplements? - Baltimore Post-ExaminerBaltimore Post-Examiner
"...But, cattle no longer feed on grass and chickens do not peck in the dirt on factory farms. Even if they did, pesticides often kill B12 producing bacteria and insects in soil. Heavy antibiotic use kills B12 producing bacteria in the guts of farm animals. In order to maintain meat a source of B12 the meat industry now adds it to animal feed, 90% of B12 supplements produced in the world are fed to livestock. Even if you only eat grass-fed organic meat you may not be able to absorb the B12 attached to animal protein. It may be more efficient to just skip the animals and get B12 directly from supplements..."