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Gypsy Horses: The
Importance of the Mare in the Breeding |
The problem with breeding lesser mares to great
stallions is that only a small percentage of those foals will be of
high quality. If there is no culling for those foals, the quality of
the breed overall goes down. Only the best foals from those mares
should be rebred. Thus, when you breed high-quality mares to
high-quality stallions, you have a much higher percentage of great
foals on the ground to maintain the quality of your breeding stock.
There is a good overview of the genetic principals underlying
the science of equestrian breeding in a book called Equine Genetics
and Selection Procedures written by the research staff of Equine
Publications, Don M. Wagoner, editor/publisher. The following
information is taken from that book.
The male normally carries within each body cell an X and a Y
chromosome; the female carries two X chromosomes. During
fertilization, the embryo's sex is determined by whether a sperm
with an X or a sperm with a Y chromosome combines with the X
chromosome of the dam's ovum. Since the presence of a Y chromosome
results in the development of the male, the stallion can only
transmit his Y chromosome to his sons and his X chromosome to his
daughters. If the genes for his desirable traits are located on the
stallion's X chromosomes, his sons cannot inherit those traits. His
daughters, on the other hand, will inherit the X-linked genes; and
even if they cannot express the traits, are capable of passing them
both to the male and female offspring.
Distant relatives have little influence over his actual genetic
makeup. An exception is in line breeding. A stallion advertised as
the "great grandson of a world-famous sire" may have inherited very
few of his great grandfather's genes.
Selection of the best stallions from the best families offers a
far greater chance of producing superior offspring than if the
breeder uses an outstanding sire from a relatively obsure family.
Horses from successful families usually produce above-average
offspring more consistently.
Although every foal receives half his genetic makeup from his
dam and half from his sire, many feel that the dam contributes more
to the nature of her foals than does the sire. This additional
contribution is due to maternal influence. The theory of cytoplasmic
genetics supports this theory.
The success of the culling process depends on the ability to
distinguish between genetic and environmental variation and
selecting only those individuals with superior gene types for
breeding.
When horses are bred haphazardly without culling of inferior
stock, many undesirable traits may become predominant in their
offspring.
Grading is the outbreeding of a superior stallion to
below-average mares, in the hope of raising the quality of each
mare's offspring. Grading might be helpful to some horse breeders,
depending on their situations and goals. The breeder should keep in
mind that the mare is capable of limiting the quality of her foal,
regardless of the quality of its sire. Therefore, the foal sired by
a famous stallion, and out of a below-average mare, might not be
valuable enough, and be considered a grade horse.
Gyspy Vanner Horses: But What About the Mare?
"A rule of thumb in the breeding world is that you can breed a
mediocre stallion to a great mare and still have a nice foal. But
breed a great stallion to an undesirable mare? The results will be
disastrous." So states the EquiSearch Web site in an article which
suggests that "the dam affects the offspring at a rate of 60 percent
or more. In the majority of cases, breeding experts will tell you
the mare's characteristics override the stallion's." The full
article, entitled "The Mare Matters, is very interesting and is
available to read online — just click the link."
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