I'm not following your logic here unless it's tongue-in-cheek? 50 head of cattle is a very small farm. I'll leave it here for now but happy to engage in further dialog.
And it's a good question. I'd suggested (per Ezra) that new regulations affecting herds above 25 head dairy/50 head beef, or producing more than 100 tons of carbon a year, would help equalize conditions for local heirloom operations. Working on a cattle ranch was my weekend job growing up, and as we only had around 50 head, I'd assumed that was a typical small herd. But the ranch was more of a hobby for the guy I worked for; after Carrie's question, I thought about it, and realized that that's nowhere near enough cattle to support a full-time ranching operation. Assuming two years to slaughter, a 50-head herd would fetch you (based on 500 lbs. beef per head, slaughtering 50% a year, and fetching around 1.30 per pound for wholesale choice) only $16,250, a large chunk of which would have to go to medical care, overhead, and feed. Even if there is a local market for heirloom breeds, the economics of such a small herd make it infeasible. On the other hand, the 25 dairy/50 beef herd size I cited below is the threshold at which the EPA will now require ranchers to seek a carbon permit. Hopefully, those will remain free for small producers.
The more important number I mentioned is the 100 tons of carbon per year being floated for the carbon taxing legislation. Because it looks like that's where efforts will be focused for taxing carbon (rather than allowing the EPA to handle it), it's in the carbon tax legislation that I think we'll see the most impact on the beef and dairy industry. To do some quick calculations, the EPA suggests that a dairy cow produces around 142 kg. of methane per year, a beef cow 76. Neither number includes methane production from decomposing manure, but lets assume that both combined are below 200 kg. per year for dairy, 100 for beef cattle. That means herd sizes below 450 dairy cows, or 900 beef cattle, would be exempt.
It seems to me that herd sizes that large would be able to support local artisan ranching and dairy operations, and that means that taxing larger herds would help to make such smaller operations competitive. Maybe it's wishful thinking, but I'm looking forward to my "Local, Grass-finished, 100% Charolais" bone-in first-cut ribsteak over at Randall's (ah, Bourgogne).