[wyldterv]

That is one of my favorite explanations I've run across yet as to the hows and whys of linebreeding!

[prairienights]

Alright, well somebody asked me to elaborate on my views on the whole thing. First, I want to restate my position:

1) I do believe that linebreeding is beneficial in many situations, and if done correctly and responsibly can improve breeds and species.
2) As my personal *opinion* I would not center a breeding program around one or two lines so much that foals were coming out with 37.5% of related genetics such as the sire in question on the other thread.
3) I do not know enough about specific horse linebreeding programs to give a specific COI that I would consider as the preferred maximum, but I'll go with what I know about cows. COI's of 12.5% to 25% is definitely a heavily linebred animal, but if done responsibly, should still be healthy.

Mmmk, so I've said I've looked at all this more closely among cattle and even swine and sheep than I have with horses. But for those species, responsible breeders try to *never* go over a COI of 25% and most try to keep it below 1/8 (12.5%). Keep in mind that the animals that are being bred for are the ones we slaughter after 1 or 2 years at most. The breeding stock cows and bulls can easily be culled if they show defects. Anyways, these animals are being bred to be slaughtered, not to have a value that's largely dependent on temperment, performance and longevity.

The owners of the sire we were discussing in the other thread boasted that he had a COI of 37.5% Waaay over a quarter of his genes were from one gene pool (to put it in perspective, you have just a quarter of your grandma's genes).

Now it isn't just genetic diseases that show irresponsibility. There are many unseen factors. The one I always preach about is immunodeficiency. With limited genes, the horse has limited immunities, which means he's at a far greater risk to be taken down by a common virus. Just because you're increasing the homozygosity of good genes doesn't mean the bad genes just float away. A lot of these are unseen. Heterozygosity is an invaluable resource in immune systems.

If we continue to restrict genetic diversity, it's only going to get worse and worse. Our artificial breeding methods are taking animal genetics so far from natural allele frequencies that eventually it's just going to blow up in our face. Even linebreeders understand this, most food-animal opperations that are producing meat animals (instead of seed stock opps) prefer to breed crossbreeds. The vast majority of beef we eat is from crossbred animals because those animals possess hybrid vigor. Hybrid vigor comes from heterozygosity. Animals that are tougher, healthier, etc. Mutt dogs generally don't have the physical and temperment problems that plague so many of the purebreds because of hybrid vigor. Evolution, mother nature, whatever, has the perfect breeding program, IMO, and evolution certainly doesn't strive to stuff as much blood from an individual 5 generations back as it can, it makes every effort to keep away from inbreeding! You don't see those mustang studs saying to their sons "hey, come on, your genetics are as good as mine, stay around and cover some of your sisters!" No, they kick their sons out to keep that from happening!

So yes, I understand that inbreeding has its place. However, my ideal breeding plan would never produce a foal with more than COI 12.5% I'd focus on a far more natural program and maintain healthy genetic diversity.

[wyldterv]

Originally Posted by prairienights

.... Mutt dogs generally don't have the physical and temperment problems that plague so many of the purebreds because of hybrid vigor..

Actually there are many scientific studies done that disprove your above statement and the facts are that there are just as many health and temperament issues that crop up in crossbred dogs (Mutts) as in purebreds when the numbers are examined.

When OFA did a comparison of the few non-purebred dogs in it's data base (lets face it owners of non-purebred dogs seldome do things like OFA screening and genetic testing that purebred dog owners/breeders tend to do) they actually show a higher percentage of hip issues. Of course this is not a reliable screening tool to be able to then say 'therefore mutts must have a higher incidence of HD overall then PB's' because the reason most of the mutts that would be in OFA's database are there because the owner's or vet of the dog, suspected an issue and spent the money on the diagnostic x-ray.

BUT it has been shown through various records comparisons time and again that it is a fallicy that Mutts are any more (or less) healthy or have better (or worse) temperaments then their purebred counterparts, so it's not a good arguement when discussing how diluted a bloodline should or should not be.

I can't argue Cattle as I personally only know Dairy farmers and a FEW Beeg Cattle producers. The Dairy Farmers actually seldome run crossbred cattle in their operations, and want a fairly high COI in their breeding programs in my observations and besides productivity being a top thing on their list they very much DO breed for temperament because you can't have a nervous, high strung cow in the barn for milking... it leads to too many issues. You want a Cow that is natural easy to handle.

I only know Beef people that run purebred herds... 10 of them run Angus (7 red and 3 black and there does seem to be a difference in temperament between the two colors interestingly enough) 12 of the people I know run Herefords (Rocketman's two uncles being two of the people I know that are serious Beef guys) and I know ONE Limosine breeder. ALL of them run only purebred on their operations. and of the 23 people I know personally 17 of them make their full time living off of their Beef operations. I'm not sure, honestly what the COI is that any of them 'draw the line at' but now I have an interesting 'homework' topic to pursue

[ryu2832]

Originally Posted by prairienights

2) As my personal *opinion* I would not center a breeding program around one or two lines so much that foals were coming out with 37.5% of related genetics such as the sire in question on the other thread.
3) I do not know enough about specific horse linebreeding programs to give a specific COI that I would consider as the preferred maximum, but I'll go with what I know about cows. COI's of 12.5% to 25% is definitely a heavily linebred animal, but if done responsibly, should still be healthy..

Originally Posted by prairienights

The owners of the sire we were discussing in the other thread boasted that he had a COI of 37.5% Waaay over a quarter of his genes were from one gene pool (to put it in perspective, you have just a quarter of your grandma's genes)..

I'm hoping there's maybe a little confusion over COI and Major Contributor percentage here. If 37.5% COI is true, then this horse is WAY too heavily line/inbred. I'd love to see this pedigree and run the numbers on it.

Domesticated horses are generally considered to be 50% related within their respective breed. This number goes up or down when you look at the starting pools of DNA. Smaller populations like Morgans would be much more related to begin with.

It is generally accepted with horses that over a COI of 12.5% a significant loss of vigor happens.

Originally Posted by prairienights

Hybrid vigor comes from heterozygosity. Animals that are tougher, healthier, etc.

Hybrid vigor is a product of complementary heterozygosity. Breeding hybrid (or non-inbred) individuals to hybrid does not produce Hybrid vigor.

[Bodi]

I'm glad to have read the article. I personally consider linebreeding when your choosing the genetics of a specific line, or horse. When you get crossing multiple horses many times, I consider that inbreeding. I agree you need to know the horse you are using, and the genetics behind that individual that you plan on doubling, tripling, or quadrupling up. It can be very positive when done correctly. One must always be prepared however to perchance get the worst of it all.

Here is my linebred gelding.



I got a very nice looking gelding with good conformation who is very identical to his daddy in many ways. I was pleased with the cross but do not plan on repeating it. I know it's not the most flattering photo you've all seen. lol.

Nights Kahlua Luey Arabian

[John]

I grew up on a farm where the main income was from the sale of purebred horses and cattle. The farm was started in 1835 and I still have three brothers in the business. I have listened to a lot if interesting theories on the subject as well as tons of results. Without going into a lot of detail the most successful method was to have several distinct lines and to work crosses between them. The payday was when an animal was produced that was better than any of its ancestors and would reproduce these traits constantly.

[OzCowgirl]

Originally Posted by wyldterv

AHHHHh but here is where people get a bit confused... A horse that carries a recessive trait (that you're unaware of it having) May produce that trait (good or bad trait) when bred to a close relative if that relative is also a carrier, OR they may ALSO produce it when breed to a totally unrelated line and happen to be bred to another carrier of that recessive.

Something staying recessive just means that it keeps populating more and more of the populace as carriers unbeknownst to you until crossed with another carrier to produce an effective.

^^quote from Herda thread.. neat feature!!!

That is very true, and I understand it. There's always a chance.

I'll clarify my position by introducing the term CLOSEBREEDING which is breeding to siblings or parents. This is what I am dead set against.

One article I found especially interesting in my travels is this one. I read it years ago and it's stuck with me

Inbreeding, Linebreeding and Crossbreeding

Done responsibly, linebreeding can be effective. It certainly has been in my stud's early lineage. That breeding has resulted in a certain type of horse. Early on there were some train wrecks, but generations later we have a great type of cow horse, with certain characteristics known to that line.

This sort of breeding has to be done responsibly, by people who know what they're doing. Not backyard breeders.

[OzCowgirl]

Originally Posted by prairienights

Alright, well somebody asked me to elaborate on my views on the whole thing. First, I want to restate my position:

1) I do believe that linebreeding is beneficial in many situations, and if done correctly and responsibly can improve breeds and species.
2) As my personal *opinion* I would not center a breeding program around one or two lines so much that foals were coming out with 37.5% of related genetics such as the sire in question on the other thread.
3) I do not know enough about specific horse linebreeding programs to give a specific COI that I would consider as the preferred maximum, but I'll go with what I know about cows. COI's of 12.5% to 25% is definitely a heavily linebred animal, but if done responsibly, should still be healthy.

Mmmk, so I've said I've looked at all this more closely among cattle and even swine and sheep than I have with horses. But for those species, responsible breeders try to *never* go over a COI of 25% and most try to keep it below 1/8 (12.5%). Keep in mind that the animals that are being bred for are the ones we slaughter after 1 or 2 years at most. The breeding stock cows and bulls can easily be culled if they show defects. Anyways, these animals are being bred to be slaughtered, not to have a value that's largely dependent on temperment, performance and longevity.

The owners of the sire we were discussing in the other thread boasted that he had a COI of 37.5% Waaay over a quarter of his genes were from one gene pool (to put it in perspective, you have just a quarter of your grandma's genes).

Now it isn't just genetic diseases that show irresponsibility. There are many unseen factors. The one I always preach about is immunodeficiency. With limited genes, the horse has limited immunities, which means he's at a far greater risk to be taken down by a common virus. Just because you're increasing the homozygosity of good genes doesn't mean the bad genes just float away. A lot of these are unseen. Heterozygosity is an invaluable resource in immune systems.

If we continue to restrict genetic diversity, it's only going to get worse and worse. Our artificial breeding methods are taking animal genetics so far from natural allele frequencies that eventually it's just going to blow up in our face. Even linebreeders understand this, most food-animal opperations that are producing meat animals (instead of seed stock opps) prefer to breed crossbreeds. The vast majority of beef we eat is from crossbred animals because those animals possess hybrid vigor. Hybrid vigor comes from heterozygosity. Animals that are tougher, healthier, etc. Mutt dogs generally don't have the physical and temperment problems that plague so many of the purebreds because of hybrid vigor. Evolution, mother nature, whatever, has the perfect breeding program, IMO, and evolution certainly doesn't strive to stuff as much blood from an individual 5 generations back as it can, it makes every effort to keep away from inbreeding! You don't see those mustang studs saying to their sons "hey, come on, your genetics are as good as mine, stay around and cover some of your sisters!" No, they kick their sons out to keep that from happening!

So yes, I understand that inbreeding has its place. However, my ideal breeding plan would never produce a foal with more than COI 12.5% I'd focus on a far more natural program and maintain healthy genetic diversity.

Where's that hand clapping icon?

My thoughts exactly. Especially the bolded part

[prairienights]

Whew, glad somebody agreed with me

[Bodi]

Originally Posted by OzCowgirl

CLOSEBREEDING which is breeding to siblings or parents.

Done responsibly, linebreeding can be effective.

This sort of breeding has to be done responsibly, by people who know what they're doing. Not backyard breeders.

"closebreeding" can also be done responsibly by people who know what their doing. It has been done numerous times by many different well known breeders of different breeds. Just to clarify I'm putting this out to everyone. It can be just as effective a tool to breeding when in the right hands.