Is it true that in order to have a colt you breed a mare in AM, and to have a filly breed mare in PM?

Question

How often do most mares come in season---every 28 days?

Answer 1

No, s*x is determined by the male's sperm, not the time. About your mare's cycle, it really depends on the mare, some mares can be quite regular, every 28-30 days, but then I have seen mares be irregular, every 2-3 months too. There is a hormone shot that can be given to your mare to 'bring her into season' that your vet will have if you want to schedule a breeding.

Answer 2

no it is not true

Answer 3

Nope, that's an old wive's tale. Mares will cycle approximately every 3 weeks.

Answer 4

This is an old wives' tale- there is no truth in it at all !!! The sperm from the stallion determines the foal's gender, just like sperm from a man determines which gender a human baby will be. Most mares are in season every 21 to 30 days during the normal breeding season, which begins in March and peaks around the time of the summer solstice in the Northern Hemsiphere, and is reversed in the Southern Hemisphere. The actual timing of the esterus cycle is dependent on the individual mare. Hope this helps.

Answer 5

There is some validity to that old tale. It takes thousands of sperm to create and opening to the egg, for one sperm to enter and impregnate an egg. It  goes without saying that a stallion is freshest in the morning before he has covered any other mares or been collected from. Slow,  low numbed sperm-counts are alright for creating filly's but males need more  and swift sperm. If your playing it safe, have the sperm evaluated before you use the horse. Most studs are best at the AM. I don't care if anyone else agrees,time in the re-pro lab is time well spent.( but rough dinner table conversation for the average home...)

Mares vary, and most come in at 3 weeks often at the same time as each other if kept  in a close location. Try regumate and ultrasound for  horses if scheduling is busy.

Answer 6

No It's not true not even close to true it is in the genetics and every three weeks

Answer 7

To answer your last question first:  when I was in college, Norm Dunn, the director of the Arabian Horse program at Cal Poly Pomona, had this to say about mares and their reproductive cycles:  "The only thing consistant about the mare's reproductive cycle is that it is inconsistant!"

How right he was.

For starters, mares are what are known as "seasonally anestrus."  This means that most mares in the equine population only have an active estrus cycle for part of the year, typically starting in the mid-spring and peaking around August in both duration and intensity.  The estrous  cycle during the height of the spring/summer, when mares are most likely to be cycling both strongly and regularly, AVERAGES 21 days.  Some mares go longer, some mares go shorter.  It is worth noting that a mare who may be cycling every 20-21 days at the height of summer may be cycling every 28-35 days in the early spring and late in the fall, or may not be cycling at all.  

The estrous cycle is linked to the daily photoperiodicity-- a mouthful to say, meaning only that as the days grow longer, mares begin to cycle with greater regularity and intensity.  This is why, long about December or January, Thoroughbred breeders start putting their barren and maiden mares under lights in the evenings:  to fool Mother Nature.  Artificially increasing the photoperiod by putting mares under lights causes them to come into heat earlier in the year than they would otherwise, and to be more likely to ovulate regularly.  (Back when I studied such things, we were told that on average, putting mares under lights gave you one extra heat period during the breeding season to work with, which was important with a mare booked to a stallion with a full book.)

Of course, mare owners know that mares can be counted on to come into heat when there's an especially important horseshow or race;  and to go out of heat just as the van they're riding in rolls up to the breeding shed of the farm where they've been taken to be bred.  Murphy's law, as applied to mares.  ;-))

What has been found with regard to breeding to get colts vs. fillies is that, ON AVERAGE, the male sperm swim faster than the female sperm, but the female sperm live longer in the mare's reproductive tract than the male sperm.  So, theoretically, if you want to produce a colt, you want to breed the mare as soon as possible after ovulation, in order for the fastest swimmers-- the male sperm-- to reach the ovum first.  If you want a filly, you breed the mare as long as possible before ovulation, so that by the time she ovulates, the male sperm have already died and the female sperm are waiting.

In practice, especially with a fully-booked stallion, you don't get to make these choices.  You get your appointment in the breeding shed when you can, and the stallion's management doesn't want to mess around with nonsense about breeding to conceive a colt or filly.  The ideal for the stallion's management is one cover, one pregnancy.  So they want to breed every mare as close as possible to ovulation, which is the optimum time to assure conception.  And they may be juggling several mares all in heat on the same day, which means someone is going to get missed and probably have to have shots to bring her back into heat and ovulation artificially to work with the stallion's schedule.

Best advice to you if you have a mare to breed:  expect the unexpected with regard to her reproductive cycle, and let the mare tell you when she wants to cycle and when she's ready to be bred.  Don't worry about conceiving a colt vs a filly, because by the time the baby arrives, approximately 11 months after breeding, you'll be ravingly happy for whatever your mare delivers to you.

Answer 8

No, our mares have had colts and fillies and they have been bread at all times during the day, that has nothing to do with it.

Answer 9

No its not true and mares usually come into heat every 21 days give or take a day or two.  Every mare is different!

Answer 10

Mares come into season about every three weeks, and no, it's not true.  Time doesn't determine the foal's s*x.