how do you run a closed flock

So I trusted someone that I shouldn't have and got burned. I purchased a bunch of chickens from a lady who was supposed to be reputable and wasn't. We added 12 laying hens to our laying flock and about two weeks later two of them turned up dead with what looks like a respiratory issue. Both had been dead too long to be able to get an effective necropsy done. Ivr been treating the entire flock with vetRX and keeping a close eye for the last 8-10 days and all seems well. Still, to be safe and make sure nothing gets out ive decided to operate that flock as a closed flock(nothing in and nothing out.) I have 130 laying hens in that flock that I sell eggs from. At some point I would like to expand our egg production.
So my question is this. If I start a second flock, how far apart do they have to be. I do rotational grazing and I have figured out that I can keep the pastures at minimum 100' apart at all times. I can also allow the pastures to rest for more than 2 months in between rotations. Are these conditions enough to keep things secure?

Any suggestions are appreciated.

I'm not sure about quarantine distances... But; for a closed flock (line breeding), it is done something like this:







Example taken from HERE

I guess I'm using the term wrong. I just need to figure out a definite distance to separate the two flocks.

It depends on the disease. Mareks stays in the soil for 10 years. Some chickens do not show symptoms but are carriers. Most respiratory diseases can be carried by the wind - like corn pollen. The only way to have a closed flock is to raise your own chickens from eggs that you hatch. Don't be to quick to judge the other breeder of chickens, your chickens may have carried the disease that killed the new ones and the new ones were just more susceptible to it. I have seen it happen. We have brought other chickens into our place but they stay in quarantine for a minimum of a month. Usually we just set eggs from the best layers under some of our game hens and let them raise up new layers for us. You can use an incubator but hens are less fuss in brooding them and require no electricity.

The only reason I am sure that the sickbess was brought in is that we noticed some of the birds just not looking right as we were taking them out of the crates. While they were in quarantine it just got worse.

If definitely not mareks or any of the other major diseases. My vet and I already ruled those out. Everywhere I look I see quarantine pens should be 100' from any other birds. Is this an acceptable distance for a flock that you just aren't sure of. If they are a carrier of something then I don't want it to spread.

Kelly Klober (of the Storey's Guide series) on breeding up your flock. I thought it was an awesome lecture.

I'd accept losses and cull hard. Buying from outside the flock always carries some risk. As far as breeding within the flock. Line breeding can work but it can get pretty complicated. Also keep in mind that line breeding is still inbreeding although generally not as close as parent offspring breeding. With a little bit of leg work and probably banding some birds you could try cyclic breeding. It seems a little confusing at first but it's actually simple and ensures genetic diversity within a closed group. Choose your best animals, divide them in to four groups and only breed in a circle while selecting for desired traits. In your case things like feed conversion, foraging ability, number of eggs, egg size and uniformity. The selecting and culling of animals is the hard part.

~inbreeding vs linebreeding

http://davidcavill.wordpress.com/a-beginners-guide-to-inbreeding-and-line-breeding/

~cyclic breeding done with pigs
http://www.gosamerica.org/breed-info.html

I've had very good luck with Murray McMurray hatchery, never had a problem with chicks from them.

I let the broody hens hatch eggs I select, and started with a mixed flock 6 years ago. Now they are really mixed up. One thing to keep in mind is that the roosters you keep are going to have a far greater influence on your future flock, which means, in my case, if I decide my flock are not heading the direction I want, I get half a dozen chicks shipped to me, or from a known source, of a breed I think will bring with it the qualities I think I've lost. Either straight run or pullets work, because when is there not at least one cockerel in a dozen pullets? If you really want to choose that rooster, get a dozen cockerels, raise them all up, choose the two or three that you really like.... grew faster, gentler, more aggressive, lower pitched crow, more solicitous to the hens and chicks, whichever traits you like best.

I had been selecting for a beautiful combination of grey blue and rusty red plumage, (with good egg production) but this summer those birds seemed to spend a longer time re-feathering after moult. Not so sure I'll continue with that. I like the heavy body of the dark cornish chicken. When ever the flock gets scrawny like a leghorn, then I keep a cornish type rooster.

Not that I like the culling, but deciding how I want to shape my future generations of chickens I enjoy. I have 120 square foot enclosures, so I can put a rooster in with a few hens I want to cross with him, gather the eggs for a week, and put them in the cartons to sell ( the sperm lasts awhile in the hens, I don't know how long, but I don't want to wait longer than a week, but research it if you really want to know) then, after the appropriate time period, collect those eggs and give them to a broody hen, or put them in the incubator. I also use the smaller separate pens if I want to figure out who is laying and how frequently, and who is eating eggs, that kind of thing, but I never want to keep a group separated from the rest of the flock, because they do have their affinities for one another, their friends and frenemies, and if the chickens are strangers to the group by the time they rejoin the group, then that stresses every one, and egg production falls for awhile.

IMO, line breeding, inbreeding is not that big a deal. Where it is a problem is when there is no sense to the culling. For example, you could start with a dozne chickens that had the same mother and father, feed them and let them breed and hatch eggs, all the while allowing them free range. The culling would be done by the hazards of life, getting stuck, getting lost, drowning, getting caught by predators. These hazards would be doing the culling, taking out the individuals that are least suited to the life available. Further, the most vigorous individuals may be able to better utilize the food available to them there in that location. They may be better able to learn from each other, the possibilities are endless, but generation after generation, you are getting the flock that will best utilize the niche available to them in that time and place.

Just like magic, I love it!

Thekla