If one has an eye to breeding, here is a copy of something I wrote on our Gypsy Horse forum, some time ago.
I've been doing a bit of thinking and research again, on breeding, pedigree knowledge, inheritance etc. We have discussed here in the past, how incredibly important good mares are to a breeding programme, but I'm carrying this a little bit further here.
For generations, breeders of all kinds of animals, have often relied upon the knowledge of the male, when considering breeding. ie. His quality, get, pedigree etc. Many in the past, bred mares of poor or iffy quality, to superior stallions, with the thought that he was bound to produce always, quality offspring. Modern thinking and knowledge however, has told us that the mare used, is just as important as the sire. In some ways, even much more important.
Genetisists tell us that the fact is, that certain qualities inherited from DNA on the x-chromosome can ONLY be inherited from a mare. So down the line, the maternal granddam, grandsire and their quality, cannot and should not, be ignored.
We all know, that very horse has 2 chromosomes that determine gender.
A mare has two X-chromosomes, therefore a female.
A stallion (XY) has one X-chromosome and one Y-chromosome, therefore a male. When a foal is conceived, if the Y-chromosome fertilizes the egg, the foal will be male (XY) because it will then have an "X" from the dam and a "Y" from the sire.
If the sperm fertilizing the egg carries the stallion's X-chromosome, the resulting foal will be female - XX.
A mare, contributes one of her two X-chromosomes to her foals, both male and female but when a stallion gives an "X" to his daughters, it is the X-chromosome he inherited from his own dam.
His sons NEVER receive his X-chromosome, because he has given them (obviously) his Y-chromosome instead. However, his sons DO receive an X-chromosome - one of the X-chromosomes contributed by their dam.
And this gets even more interesting. One of those would have been inherited via the dam's dam, and the other came down the "X-trail" from her sire's dam.
Geneticists have determined that certain genetic material is carried on the X-chromosome, including that for the large heart, and intelligence. Most probably, there are many other genes passed down on the X-chromosome, many of which we probably don't even know about at the moment.
So now, understanding that certain superior qualities can ONLY be inherited from a mare, her expressed qualities and that of the maternal granddam and grandsire suddenly become incredibly import.
Lizzie
