Good for you. In my opinion, you are doing the right thing. It seems to me like there should be demand for bulls from a clean herd.
If I was you, I would not cull the carriers however. You can breed them to another breed for hybrid vigor and sell the calves for beef. Or you can breed them to a clean Charolais, and only retain the daughters that test clean.
I did not cull any of my carrier cows. Since I am mostly a commercial herd, I just bred them all to a clean bull, and sold their calves with the rest of the stocker calves. If I had a female from those crosses that I decided I wanted as a replacement, I would test her first. I never sell anything that could be a carrier to someone who is planning to use them for breeding. When I had a request for heifers and the person chose a potential carrier, I tested the heifer first, at my own expense. If the heifer was a carrier, they had the option of choosing a different heifer or not buying anything. At this time I have no potential carriers left in the herd. They have all aged out or been culled for another reason. That can change the next time a defect is identified.
Linebreeding to me, would be when the related relatives are several generations removed. I suppose we might say all purebred registries are the result of line breeding, although I seldom see anyone calling it that. For example, you will see many of the same bulls in most Angus pedigrees. I expect this is true in most breeds. There are a few animals in every breed that have been very influential. When you look back in a pedigree you will likely find many of these same animals in multiple lines of the pedigree. When someone says they line bred, it probably means they intentionally included a desirable animal several times in the pedigree within the first three or four generations. When I say inbreeding, I am referring to animals that have the same animal in the first one or two generations, such as daughter to father, or mother to son, or perhaps sister to brother etc.
I have been through the testing process to get rid of possible carriers in my Angus herd several times now. I have tested every bull I use her for all identified defects. I refuse to use an AI bull that has not been tested, even if his pedigree says he is clean. I have also tested all foundation cows for every known defect, whether or not her pedigree indicated she might be a potential carrier. All of my replacements receive a DNA profile once they have raised their first calf. Those profiles include a check for accurate parentage, so since both parents have been verified clean, no further tests are required. With AAA these tests are all quite reasonable, and if you have sent in DNA in the past, it is still on file with AAA, so any further defects can be checked without needing to collect more samples. This was a blessing for me, because I had DNA on file for cows that were long gone from the herd, and testing them meant I did not need to test their ancestors.
