Using 2 studs with 1 bitch during breeding
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I agree with everything said above. My understanding is that the eggs are all released at the same time (like within 24hrs) but the sperm can hang around for 5+ days. So that is why the window for breeding is several days…to make sure you don't miss the eggs. That way nature prevents the situation you described..pups not being 'done'. But what does create pups not appearing to be the same gestational age in the same litter is where the placenta attaches to the uterus. Apparently, there are occasionally "bad" spots to attach. Also, if there are indentical twins in a litter (in the same sac) one may be underdeveloped....but from what I have heard, this rarely happens.
I am no expert, but I did a lot of reading before Bella's litter...and this is what I can remember :)
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I have no problem with breeders who choose multiple sires as a breeding option. If both males are in close proximity of one another, there is no reason why natural breedings can't be done. If the males are located too far apart for daily breedings to the bitch then one or both may need to be AI'd. DNA testing both sires, the dam, and every puppy is required and then AKC registration can run several hundred dollars but there are many situations when it is well worth the expense.
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I remember seeing a breeding on a website last year using dual sires, one of which was a full African and the other a high percentage African. That made sense to me as you're not really sure what you'll get with full Afs particularly if they have not been bred before. In theory under ideal circumstances, you would get some idea of what they both might produce with the same bitch without having to wait around to do multiple single sire breedings. I didn't look check back to see what the actual parentage ended up being in the litter.
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From what I have been able to find out from people who have attempted multiple sire litters, the most effective way to actually get puppies from each sire is to do surgical implant 72 hours after ovulation with one sire's semen in one horn and the other sire's semen in other horn of the uterus. In the majority of natural breedings with multiple sires the puppies are either all from one sire or only 1 or 2 from the second sire even in large litters.
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I knew Kittens could have different fathers but wasn't sure about Dogs. This explains how our crossbreed Dog was so very different from the rest of the Pups. He wasn't like mum or dad and his sibs were medium sized Black and white collie types. He was a massive Red Lab type.
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From what I have been able to find out from people who have attempted multiple sire litters, the most effective way to actually get puppies from each sire is to do surgical implant 72 hours after ovulation with one sire's semen in one horn and the other sire's semen in other horn of the uterus. In the majority of natural breedings with multiple sires the puppies are either all from one sire or only 1 or 2 from the second sire even in large litters.
I don't think I would do this with a breed like the Basenji where an average litter size is 4-5 puppies but it make a lot of sense to do in breeds that have litter sizes of 10+ puppies.
I'm puzzled why planned multiple sire litters would end up with one male predominating fertility? Dogs and cats that run loose and breed randomly sometimes have litters where every puppy or kitten has a different sire. They breed to multiple partners every day so it would seem that breeding a bitch to both males daily would increase the likelihood of both sires fertilizing the bitch. Does anyone know if any studies have been done on this?
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I'm puzzled why planned multiple sire litters would end up with one male predominating fertility? Dogs and cats that run loose and breed randomly sometimes have litters where every puppy or kitten has a different sire. They breed to multiple partners every day so it would seem that breeding a bitch to both males daily would increase the likelihood of both sires fertilizing the bitch. Does anyone know if any studies have been done on this?
The information that I have seen does not support that most mixed breed litters have multiple sires. Though there may be 1 or 2 pups with a different sire much of the variety seen in mixed breed litters are because there is more diversity of alleles in the parents (often mutts themselves) so less uniformity in the litter.
I do believe that there a few studies that show that nature has made it so that once a male has successfully impregnated a female there are biochemical changes that occur that make a subsequent sire less likely to be successful in some species.
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Seems like a question for Hutchinson. I know he does tons of implants, he may know about actual splits. Probably AKC does too. If I can remember I'll look or ask both.
