colts verses fillies

[JennyB]

Questions:

Do you feel that your stallion decide the sex of your foals?

Do you think it's a 50/50 ratio always at getting colts and fillies?

Do you feel there are more colts born in your lifetime of seeing all different breeds of horses?

Do your younger stallions produce more fillies and when they get older do they produce more colts?

Thanks,

Jenny

 

[Mona]

I have heard/read that the stallion determines the sex, and that it can vary, and not be a 50/50 ratio from one stallion to the next.

 

[Lewella]

Scientifically the stallion determines the sex of the foal. All the eggs a mare produces contain one of her X chomosomes. 50% of the sperm a stallion produces contain his X chromosome and 50% contain his Y chomosome.

Uterine PH of the mare and timing of the breeding influence what sperm live and what sperm don't. A low ph (acidic) is more condusive to the survival of X chromosome sperm. A high ph (alkaline) is more condusive to the survival of Y chromosome sperm. Y chromosome sperm swim faster but live a shorter period of time thus breeding close to ovulation favors the Y chromosome sperm. X chromosome sperm live a longer period of time and swim slower so breeding further before ovulation favors the X chromosome sperm.

Experienced pasture breeding stallions will sometimes wait to breed a mare until right before she ovulates. Those stallions will produce a higher percentage of colts than fillies because those close to ovulation covers favor the Y chromosome.

There is some evidence to support feeding mares an acidic diet to encourage the survival of X chromosome sperm and thus produce fillies. Ultrasound can also be used to determine interval to ovulation and the breeding can be timed to favor X over Y or vice versa.

 

[shorthorsemom]

In cows for us breeding early in heat cycle flavors heifers and late flavors bull calves. Same with humans by the way. Early favors girls and at or after ovulation flavors boys aparantly the boy swimmers are faster and the girl swimmers last longer so they can hang out waiting for the egg so early flavors girls. We do Ai breeding on our cows and "afternoon vs morning" breeding can make a difference when we r not using sex selected.

 

[shorthorsemom]

Favors not flavors ..lol kindle changing words.. hilarious. Sorry

 

[FurstPlaceMiniatures]

Ditto to lewella. Also, in cattle, we can sex semen. Dye is added to sperm to light up chromosomes. Being that an x chromosome has more surface area,, it shines a hair brighter. Sperm cells are then run througha special machine that sorts "dull" ones from bright ones, and are packaged accordingly. I don't think horses have sexed semen yet, as equine ai isn't as popular as cattle ai.

 

[Jill]

I think that the sperm of the stallion determines the sex of the foal, but that the environment within the mare (which is dictated by conditions) favors the sex of one or the other, depending on what the environment in her is like.

Specifically, I feel that when our mares are gaining weight during conception (in a weight gain cycle), they are more likely to conceive a colt. When they are in a weight loss cycle during conception, they are more likely to conceive a filly.

Since 2001, we have had 13 foals total, which includes one slip at about 8mos. 10 fillies, 3 colts. Not enough to call it science, but I have correctly predicted the sex of each foal since reading a study that lead me to the conclusion I shared.

 

[ohmt]

Also, a stallion may have X chromosome sperm with little motility or Y chromosome with little motility. I have a stallion that has produced 20+ foals, but only 4 colts of the bunch so I'm fairly certain his X chromosome sperm just have better motility. He is an older, experienced stallion and the only one I pasture breed with.

We have had almost all fillies for years and years until this year. This year we got 10 colts, 2 fillies. Since we have pretty small foal crops and this one was abnormally large for us, our odds quickly got much closer to 50/50 lol.

 

[JennyB]

I appreciate your comments and would like more. I am not sure that all the scientific data is always 100% as I see to many stallions who have all or way more fillies or colts and the same with a mare, even a mare who has all fillies or colts from a different stallion every time.

What would explain why a stallion has more fillies when younger and more colts when older?

I find this VERY interesting and am doing more study on this subject.

What are your thoughts?

Thanks,

Jenny

 

[Ashley]

Well my mom has a mare that has had 13 foals, of which only 3 have been fillies. These 13 foals have come from 5 different stallions. The fillies are all sired by different stallions.

 

[Lewella]

If you are pasture breeding many pasture breeding stallions will sire more colts when older because they are covering the mares fewer times and usually breeding them closer to ovulation.

Hand bred stallions where the breeder is good at timing won't sire more colts than fillies as they get older. My old stallion Roadrunner Cody's Copy sired twice as many fillies in his 20's than he did colts. Of Royal Red Viking's 29 hand bred foals concieved at age 20 or older only 11 were colts.

 

[paintponylvr]

Interesting topic!! LOVE IT.

When we were standing our first Shetland stallion we did a combo of live, hand cover and pasture breeding (the smaller Shetland and Hackney mare). When I bred the mares in the AM, I found I got fillies and when I tracked it and bred in the PM, we got colts. We didn't ultra sound, so don't know exactly when each mare was ovulating. Had one mare that was bred every other day for 21 days in a row - he got darned tired of her and would "hide" in the corner of his pen when he saw me coming w/ his breeding halter and she was out. We DID get her in foal (amazingly) - and she foaled a colt! He was actively covering other mares at the time (hand breeding). OUt of 32 foals - 19 were fillies and 13 were colts. The most recent were all stud colts. Before he was injured (and subsequently euthanized), he covered a mare in May - one good cover and one...soso. This will be his last foal and we don't know for sure that the mare is preggers yet. She was covered around 10:30 am - both times.

He sired all fillies (5) when bred to our one Hackney mare. She produced one filly and one colt by 2 other stallions. She was handbred after foaling on her heat cycles but also ran in the pasture with him several times.

He sired 3 fillies and 2 colts out of another mare that he was bred to. Don't know when mare bred for the first filly (surprise pasture breeding in MT before moving to NC - right after losing her 1/2 arab colt at birth)... Others - know that first colt for us was produced from PM breeding - not sure on the rest...Notes disappeared when computer crashed and didn't have info printed or online (saved). Sired one colt and one filly out of another horse mare we owned. Ditto the notes, tho.

He sired two fillies out of an arab mare bred in AM only. Sired two colts out of two other Arab mares when bred in PM only. Sired a filly out of an outside mare bred both am and pm on different days...

**********

"New" stallion - first year no mare bred to him settled. Was pretty worried about it - hand bred 4 mares to him live cover. VERY shy breeder! So far, he's sired 5 fillies and 3 colts for us. BUT I don't know for sure if they have been just AM covers or not as I often turned the mares back out with him after actual hand breeding was done... 1 stud colt was a complete surprise this spring - as the mare was with him (13.1 hands to his 10 hands) and was not hand covered using the raised ramp that used in the two previous years' breedings - guess it was jsut a matter of figuring things out, LOL. She doesn't usually squat very low - figured that she must have laid down for him. DID NOT put her out with him again this spring after she foaled. They do miss each other, tho, constantly talking to each other even when not in heat. Want to sell the mare - get down to all purebred Shetlands.

The two sibling colts look to make a matched pair in height and movement - should mature around 12.2 hh and will make a very fancy driving pair!!! or single riding/driving ponies.

AFter originally not wanting to breed too many mares this past spring, I bred way too many!! Not sure who is and isn't in foal yet. Most were bred in AM hand breeding but then again, turned the mares out with him forup to 3 weeks after the last hand cover. One little shetland mare is still running with him - she came back into season after originally bred and I turned her out with him... Believe she is in foal now, but am/pm??... We'll see what happens.

 

[chandab]

Interesting topic!! LOVE IT.

When we were standing our first Shetland stallion we did a combo of live, hand cover and pasture breeding (the smaller Shetland and Hackney mare). When I bred the mares in the AM, I found I got fillies and when I tracked it and bred in the PM, we got colts.

Interesting... I bred three mares last summer, and got three lovely colts. Due to my schedule, I'm pretty sure all three were hand bred in the evening. I'm going to have to try morning breeding next season and see if I get some fillies next time around.

 

[Minimor]

Obviously the stallion is the only one that passes on the Y chromosome, so scientifically it is the stallion that controls sex of the foal. However, as others have already said, various factors can alter the 50/50 colt/filly ratio that any stallion should theoretically have.

Mares can be more acidic or alkaline, and therefore may favor colts or fillies. A stallion may perhaps have some flaw that causes him to have poor motility or poor survival rate of either his x or y sperm--in that case he will favor colts or fillies.

Long ago someone told me that if I wanted to get a filly every time I should breed the mare on her first day of being in heat, and then don't cover her again. That almost certainly will result in a filly. Why? Because by breeding early, before ovulation, the sperm are already right there when she ovulates--and by the time she does ovulate the male sperm (which have shown to be shorted lived than the female sperm) will be dead, and only the female sperm will be there to fertilize the egg. This "system" can work if your mares all have a 5 day heat cycle. I have found that many mini mares tend to have longer cycles--some do go just 5 days but a good number do go 8-10 or even 14 days in heat. If they ovulate early in the cycle this sytem would still work; if they ovulate on day 7 or 10 then obviously it will not work at all--because after 7 or 10 days ALL the sperm, not just the male ones, will be dead and the egg simply won't get fertilized. The mare will not become pregnant at all if she isn't bred after day one of her heat cycle.