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Inbreeding to Grey Flight

FIRSTCROSS 2.0 PROVIDES THE MEANS TO DETERMINE WHAT STRAINS WORK BEST

By Roger Lyons

        Generally speaking, inbreeding to females tends to differ in one important respect from inbreeding to males. Sires may have superior offspring from a wide variety of mares, but the best strains through which a female descends will often have the same sire or sire line since breeders tend to return a mare to the sire or sire line that has worked for her before. For example, Grey Flight (Mahmoud ex Planetoid, Ariel) produced by Bold Princess, Pleasant Flight, and What a Pleasure by Bold Ruler and another foal, Misty Day, by Bold Ruler's sire, Nasrullah. This illustrates how great dams often introduce the possibility of inbreeding through strains that are related on both the sire and dam sides.
        Inbreeding through closely related strains is a breeding methods that has been widely acclaimed, and for good reason. While there are many opportunities to inbreed to males through strains that are related on both the sire and dam sides, such opportunities usually involve the same sire line and broodmare sire line. In such cases the two strains are only fractionally related to one another. But, cases of inbreeding to females more often involve full-sibling strains, and, in general, the strains tend to be more closely related than when inbreeding to males.
        Grey Flight is distinct from many other important dams because she also produced significant offspring by a sire who was a highly compatible international outcross to Nasrullah line. That sire was Princequillo, by whom Grey Flight produced Misty Morn and Misty Flight.
        This introduces two alternative approaches to inbreeding to Grey Flight. If one has a mare with Grey Flight through a Nasrullah-line strain, one can either select a stallion with another Nasrullah-line strain or select a stallion with a Princequillo-line strain. In the former instance one is inbreeding through individuals related on both the sire and dam sides while in the latter instance one is inbreeding through strains that have different, but highly compatible sire sides. The question is, does it make any difference?
        According to our list of stakes winners inbred to Grey Flight, it does indeed make a difference. Of the 18 stakes winners listed, only three combine two of the Bold Ruler strains, and another combines a Bold Ruler strain with the Nasrullah strain. Only one stakes winner combines the two Princequillo strains. By contrast, 10 stakes winners combine a Bold Ruler with a Princequillo strain, and another three combine the Nasrullah strain with a Princequillo strain. Clearly, the combination of strains involving different but compatible sire lines has worked best when inbreeding to Grey Flight.
        One ought not to infer on this basis that one method is better than another with respect to any female ancestor. We know that certain full-sibling strains, such as Round Table and his full sister Monarchy, have a powerfully favorable effect. Not all females will present the same opportunities as Grey Flight, and some that do will not work in the same way. This underlies the importance of having information pertinent to specific female ancestors, such as that provided by the CompuSire FirstCross 2.0 module.


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Copyright © 1998 Roger E. Lyons
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