Dam lines are frequently used to name females, e.g. Olde House Caroline 8th. However, it seems to me that unless such founding dams have frequently been bred to sires of similar breeding, then the genetic significance, at least the nuclear DNA of the founding dam in the line, is progressively reduced with each generation. However I understand that the mitochondrial DNA within the unfertilised cell, which has important function, no doubt amongst other things, in respiration (powerhouse of the cell), is inherited from the dam (I see this absolute position disputed), although this varies in species but apparently female ancestry in cattle can be studied through the relatively unchanged passing down of mtDNA from mother to her offspring. One would like to know whether the eggs formed in the female, early on in her life, indeed during embryonic developement, are contributed to by her sire only with respect to half of the half set of nuclear DNA in the unfertilised ovum, or if her sire also contributes to other ovum features, like the cell wall, the cytoplasm, etc. The question boils down to, what do geneticists like Dr. Matthew Hegarty, who provides services to HHBI, or anyone that views this blog, have to say about the importance of dam lines in one's breeding programme in the genetic context?
Traditional herefords are a small breed, but not yet as small as the Suffolk horse; breeders are pushed very hard to find diversly related sires, and not to overuse the best stallions. They use a system called SPARKS (https://www.rbst.org.uk/blog/sparks-a-toolbox-for-breeding) to encourage more diverse selection. One hears of small wolf populations becomming infertile, and being revived by less related introductions. I am wary because of my experience with Whitebred Shorthorn cattle, a very small breed suffering from so called White Heifer syndrome. I was struggling to breed fertile females.
As a seedstock producer, I view hybrid vigor as something that should be left for our customers to take advantage of. Hybrid bulls breed poorer than their conformation but inbred cattle tend to be prepotent.
All too often I have seen herds ruined by chasing the high that is hybrid vigor and neglecting the more difficult work of making real improvement. In the end, those herds lose what made them special.
Currently, I have two breeding groups and I think the closest inbreeding this year is half aunt to half nephew. I put a lot of focus on maintaining a robust genetic base. I find I have much better luck bringing in proven older genetics through AI.
I suppose if your stock has no recessive defects, that works, stamping your perceived effective type. However, surely you won't be getting the hybrid vigour?
Most of a herds genetic base is on the cow side. Your cows are adapted to your local microclimate and conditions. The best thing we ever did was to start using bulls out of our cows.