I am a first time breeder and I am curious whether "inbreeding" is a problem. For example, my mare has Cor de la Bryere on her sire's side (great grandsire). I really like Crown Affair, but his sire is Cor de la Bryere. Would crossing my mare with Crown Affair be problematic? What about a stallion with Cor de la Bryere a few generations back?
I would not want to see it any closer than 3 generations back. In a horse with no known bad traits. In a horse with some questionable traits....4 to 5 generations. It also depends on the bloodlines. Some I would not linebreed at all.
Line breeding is good for confirming both good and bad traits in horses. So I guess in any breeding you need to consider the good and bad charateristic which most like will be genetically confirmed in the foal and its future foals.
Personally I wouldn't go there due to my lack of knowledge. However I do own a mare that has multiple line breeding in her pedigree and you can see it in her and foal she has had. All good but I did allot of thinking about the mare before I bred her not due to the line breeding but more about what is genetically in her breeding.
The issue with close breeding is...are you willing to do the culling necessary. If instead of doubling up on the assets you want, do you instead double up on the faults you don't want. If you bring close relatives together you increase the chances that the qualities you love about them will be concentrated in the offspring making those offspring more predictable to transmit those qualities to the next generation. The risk is that the faults may also be concentrated so you would need to be ruthless about culling the horses with the undesirable faults as they will be more likely to transmit those faults. If you are inbreeding a truly wonderful horse with few faults then you are creating offspring that could be very strong in traits you desire. There can however be genes that carry hidden bombs like SCIDS. By itself it is no problem but by inbreeding or line breeding it increases the chance to find its match to create a disease state. Done right inbreeding can create super producers. PatO
Using very good individuals and linebreeding on a line you know and understand for a purpose is a very good way to "set" the traits you want expressed. It's been done with great success. My criteria is that and at least two "free" generations. It's important to linebreed to keep certain lines "fresh" and to increase the odds of bringing through the traits you wish to insure. You also must consider the undesirable traits and use very good individuals of quality - which should always be done in breeding.