I keep seeing this claim in these HN threads and across the internet, do you have a reliable source for this? Google brings up nothing but vegan conspiracy sites.
Yeah, this article makes more sense. My grandfather put out the blue salt blocks every year so the cows would get enough cobalt (I remember asking teachers why salt blocks were blue until one knew why). That's why this all seems like nonsense, none of the farmers I know ever gave their cows B12 supplements or have even heard of it. Now their VET might have given B12 shots to the odd calf like that article states, that I would believe.