Re: Hybrid Vigor

LGOURD@aol.com wrote:

> Terry,
>
> True hybrid vigor can also be expressed in the "mule" vs: the "hinny"
> concept.  The offspring will take the size of the mother with the mule cross.
>  Can we expect any such happening with the pumpkin?
>
> Ray Waterman/WPC

  TerryLynn answers:
   You're right, there, Ray, but that is a specialized instance, for
mules. The
resulting offspring also are affected by uterine environment. The mare's
uterus
is much bigger than that of the donkey. As a result, this cross starts
out much
bigger at birth. The mare also usually has more milk, due to her size, &
is able
to nourish a large baby better than the smaller donkey. Thus, yes the
reciprocal
cross would be smaller in most cases.
    In our own program, we find that by using a specific Clydesdale
stallion
(size, power, soundness & disposition) with TB mares ( refinement, reach
&
stretch in body build, speed, maneuverability & athletic ability) we
consistently
get the best of both sides, with the sire passing on size even though
some of the
mares are only 15.2 & the sire is 17.2 hands. The resultant offspring
range from
16 to 17.3 hands, with many 16.2's coming from 15.2 mares.
    Unusually, the F1 offspring of this sire tend to be consistent. The
sons sire
slightly lighter, more refined offspring very consistently. While the
initial
Clydesdale & some of his offspring still have some knee action; the
foals
produced by all F1s (as long as bred to TBs & Arabs) all move smoothly
with
little to no knee action. Interestingly enough, the F1 females, when
bred to TB
stallions, all produce foals finer than themselves, but heavier than
those
produced by their F1 brothers (when mated to Thoroughbred mares). All
foals
produced by the F1s are more refined than the Clydesdale, are very
athletic, move
with little to no knee action: are all good athletic horses & good
jumpers. All
are 16+ hands & all have good dispositions.
    Even though it is our own line; even being impartial, I would have
to rate
this as an extraordinary hybrid cross, due to the consistence of the
prepotency &
dominance of the F1 generation. Believe me this does not happen often.
    I recommend looking upon the hybrid results of a cross as a window
into the
future, or a foretelling of what is there in the genes. (you see it now;
but in
the next generation, it sinks back into the gene pool: its there, but
you have to
breed carefully to acquire its physical manifestation)
    It is important to remember that the genes are then diluted &
fragmented when
the F1 generation is bred on. By doing "self or sib" matings, we have a
chance to
try to intensify certain characteristics. The point, here is that the
hybrid's
size is proof that size is there. But if we dilute it or spread the
genetic
material more thinly, we lessen the intensity of the characteristic.
    A breeder will, instead, try to mate the F1 hybrid to large pumpkin
families,
in an attempt to encourage the development of a homozygous giant. The
problem
with this is that you also frequently intensify other characteristics
that are
present as well. Such as pale color or poor shape (which might not
bother some,
but are anaethema to me). Then you have to try to breed these out, &
that takes
more time.
    This is where it pays to use proven lines, where you know the
pedigree & the
genetic material that is present. Thus, there are far fewer unpleasant
surprises.
back crossing the F2 generation to the F1 or even to the Foundaing
parents, helps
to "set the characteristic".
    Sometimes a characteristic is neither completely dominant or
recessive. An
example would be mating red to white petunias, & getting pink offspring.
Thus,
you would need to duplicate the "hybridity" (genetic variation) to get
the same
result as in the hybrid. I have asked Michael to explain incomplete
dominance in
depth. He should be posting this with in the next few days.
    However, to establish the individual doninances in your F1 hybrids,
you would
need to make a few test matings. An example are the Clydesdale &
Thoroughbred
stallions in our program.
    I am going to share my personal breeding creed here with you: "Never
make a
mating that you are reasonably sure will rate below good in quality"
"always
approach a potential planned breeding by evaluating the best & worst
that could
come from this mating. If the worst will rate less than "good" ...don't
make the
cross".
    I took the initial Clydesdale, & made the assumption that he would
sire
"heavy". Since I was breeding for a lighter performance horse, I used
correct,
slim , elegant TB mares, knowing I could count on him  to provide more
muscling,
size & power on the offspring. This is what I call a "Positive test
cross". The
offspring almost can't fail, yet if he doesn't sire much muscling, I
will get a
horse that looks more Thoroughbred than I perhaps want, but is still a
good
individual. I found out what I needed to know, without producing an
undesireable
foal. I feel that every breeder has a responsibility to try to do these
positive
test crosses, rather than negative.
    Our Thoroughbred stallions are selected for soundness, conformation,
athletic
ability, disposition, beauty & refinement. The question is: "will they
sire sound
but slimmer bone?" The first thing I did was mate them to heavier-boned
Thoroughbred mares & a couple of the F1 Clydesdale crosses. The foals
would still
be acceptable, due to the parents used for the matings, even if they
were as
heavy-boned as the dams. If they were a bit more elegant, I would have
my
improved next generation. If I got heavy-boned foals, I would know the
stallion
did not sire refinement.
    The reason this kind of mating is necessary is to identify the
characteristics carried by the hybrids. Then chart their presence &
dominance by
the effects on the offpring when mated to females carrying certain
traits. Once
you have identified the pattern of hereditary for the F1 cross, you can
breed on
very successfully, & make much more rapid progress.
    This was the long way "around the barn", but I wanted to explain
thoroughly
what we have been talking about & how to implement it further. I hope I
made it
clear enough, but if not, please feel free to contact me for additional
information.
TerryLynn
Other Mailing lists | Author Index | Date Index | Subject Index | Thread Index