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How young is too young to breed a
colt? We have a coming 2-year-old who acts like he is ready to breed. We
don't have any horses to breed to him, but the question came up for
discussion last night among a group of guys. This colt was out there
showing his stuff along the fence near the fillies. Among us we had
strong opinions about how young horses could breed, how young they
should breed, and how young they could be fertile. Some of us thought
that it was okay, and others thought it might mess them up for the
future to start too early. If a colt appears to be breeding, does that
mean he is mature enough to impregnate the mare?
-- Dan
Most yearlings and 2-year-olds can and
will breed under good circumstances. There's probably not a horse
practice without a first-hand story of the pregnant filly that was only
with a colt until a year of age. So for sure, many fairly young colts
can be fertile. Some young colts are quite mature behaviorally, looking
like an old pro before the age of two if given access to fillies or
mares. Others might be awkward and slow, but given ample opportunity,
particularly with young mares of their size, will have no problem
mounting, inserting, and ejaculating normally.
One common attribute of young colts is
that their endurance and confidence might be much less than that of a 3-
or 4-year-old. If you hand-breed them, they might be shy, easily
distracted, or overly put off by correction. That is probably the basis
of concern about "messing up" a stallion by breeding him too
young. It is not wise to count on a 2-year-old being able to handle a
busy breeding or semen collection program.
We have studied colt development in our
semi-feral pony herd here at New Bolton Center. In that herd and in
other horses that have been studied under natural social conditions, the
yearling and 2-year-old males do most of the breeding of the young
fillies. The young fillies are often still living for the most part in
their natal band (band in which they were born) with their sires and
dams at the time of their first estrus.
As estrus begins, the young fillies
wander from the family band up to several times a day to join roving
bands of young bachelors. The fillies seem to actively solicit attention
from the young males. The young males take turns breeding the fillies.
They tolerate each other's awkward "schooling" mounts, and
seem to patiently wait their turn. So even though stallions might take
years to get their own established harem, most young males have some of
this style of breeding before the age of two.
The maturation of sperm production and
behavior often don't coincide. That means a young colt might be very
willing to breed and have nearly perfect form as much as a year before
his testicles and sperm production have developed. Similarly, a colt
might have apparently maturing testicles, but be immature behaviorally.
Another concern we hear from time to
time is whether early breeding influences a colt's manners and
studdishness in non-breeding situations. One episode is probably not
going to mean much, but if a young colt is allowed to breed frequently,
research suggests that his hormonal and behavior maturation might be
accelerated. That means he might be more "full of himself" at
an earlier age.
While we're on the subject, many horse
owners are alarmed when a colt mounts his mom during foal heat. This
normal behavior is seen in almost every colt at the time of foal heat.
In fact, almost all of the normal sexual behaviors---teasing, marking,
flehmen response, erections, mounting, sometimes weak thrusting--are
seen within the first week of a colt's life. They are sometimes not in
the "adult" sequence, and they might be subtle or interspersed
with action play sequences. But if you look closely, they are there.
Colts do a lot of sexual play with filly and colt playmates. They
achieve erections, but rarely ejaculate in the play form of sexual
behavior.
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