Too closely related to breed?

[Alaska Satin]

Linebreeding/inbreeding is more a succesfull yes/no depends on term used thing. We see the problems in certain groups of people where marrying cousins is common and has been happening for generations on end. Or the even closer family ties in some royal houses where brother - sister, niece - uncle and so on happend for max 4-6 generations before the whole family pretty much imploded from health problems, infertility and so on.
But somehow it is not a problem in animals. How much of that is truth and how much is not a problem traits that are ignored because show quality animal goal creates tunnel vision?
I just care about having healthy animals with inate good mothering skills giving 3-5 kits (5 preferred, but largest here is 7 from rex dwarf doe that is 5 years old now, was proven 5 and this is her second litter of 7 from 2 different bucks) and friendly/low stress behaviour. Coatcolors are fun, but i don't breed siblings for it. Might have to breed father to daughter due to buck shortage, but that litter will be for the freezer.
I know of another meatrabbit breeder who bought breeding stock from "good" breeder, they turned out small litters and weird problems and she later found out they where multigenerations of same litter matings.
I also hear a lot of show breeders finding small litters normal (1-3 kits for dwarf breeds). And i know fertility issues go with inbreeding. So I keep having a hard time believing the "it is not a problem" claims. It is blatantly obvious in many dogbreeds that the breedstandard stands in the way of health and welfare and there we know how inbred (and genetically tested free of the whole alphabet of whatever) they are. And even the fully tested animals have health issues like foodallergies, skin problems and so on.
So what is breeders blindness and what is truely not an issue?

In my experience, dog breeding and dog breeders are about as different from rabbit breeding and rabbit breeders as you can get. To the point of this discussion, in North America most dogs are not bred for meat production, unlike many breeds of rabbits, so it seems logical that overall you might see more reproductive issues from linebreeding in dogs than rabbits.

Many breeders of purebred show rabbits, especially the meat breeds, also use their rabbits to feed their families, so while we're breeding to the standard for show quality, most of us do not ignore the other aspects of reproductive fitness. I have been linebreeding my Satins since 2006, which has included occasional sibling crosses. I select for good production, breed standard and actually I put a premium on temperament - not only do I not want rabbits attacking me or my kids, but tame, calm animals are generally healthier as well. Currently my breeding does have litters of 10-16 for the first year, and 6-10 for the next two years; when I started, they generally had litters of 5-6. They rarely miss conceiving, are good mothers, and usually give me 4-6 litters a year. My animals now make senior weight at 5-6 months instead of the 12-18 months it used to take. In fact, pretty much every parameter used to measure reproductive fitness has improved since I started, mostly because if it did not, the animal did not stay in my barn. At the same time, I went from never winning even at the class level, to winning Best of Breed/Best Opposite and Best in Show/Reserve in Show nearly every time we hit the show tables. There is very obviously no inbreeding depression in these Satins; yet in nearly two decades and many hundreds of rabbits - maybe thousands at this point - I have introduced exactly three unrelated animals into my program, for very specific reasons; and just about every rabbit in my barn has the same six progenitors in the far reaches of their pedigree.

That said, some breeders do not mind smaller litters, especially breeders that don't eat or sell their extras. And honestly, fewer kits are a lot easier on some of the smaller dwarf breeds than trying to gestate, kindle and feed 6-9 kits. Our mini rex routinely had 6-9, but our tiny Polish are much healthier raising 3-6. They can raise more - they have been good foster mothers to Satin kits from litters of 16 - but that's a lot to ask of a tiny 2-1/2lb body.

So, I think you're right that linebreeding is a "depends" thing. It depends on the breeder and how vigorously he or she selects for things that are important to them. But to be honest, a breeder who is not selecting for desirable traits is probably not going to have much better luck with outcrosses. It also depends on the quality of the stock you start with - you can't eliminate an undesirable trait and replace it with a desirable trait if the latter is not there to begin with.

 

[Preitler]

Biggest difference between breeding rabbits to marrying cousins and breeding dogs really is that there noone is willing to eat the culls

 

[judymac]

We see the problems in certain groups of people where marrying cousins is common and has been happening for generations on end. Or the even closer family ties in some royal houses where brother - sister, niece - uncle and so on happend for max 4-6 generations before the whole family pretty much imploded from health problems, infertility and so on.
But somehow it is not a problem in animals. How much of that is truth and how much is not a problem traits that are ignored because show quality animal goal creates tunnel vision?

You have hit upon the crux of linebreeding. It intensifies the existing traits, both good and bad. This can be both a good and bad thing. If you use the opportunity to weed out any undesirable traits, keeping only the very best for breeding that is meeting your herd goals, it can be productive. If you keep or sell all the offspring because they have some famous show winner in their pedigree, and not because of their own qualities, you are asking for trouble. Thus the problems with royalty you mentioned, where royals are chosen as breeders based on their birth order, not their inherent qualities. With livestock, we can make different choices than we do with people, which is why the current laws concerning human close-breeding exist.

We've all come across animals that purportedly came from "good stock" that were truly sub-par. A famous name on a pedigree does not make a quality offspring. If your herd is suffering from a recessive negative trait, like poor tooth alignment, linebreeding may be a very difficult issue for you.

Outcrossing has its own issues, like bringing in recessive traits that you didn't have to deal with before, or negative modifiers that reduce the depth of your rufus reds or the depth of color in the fur or the placement of spots on brokens. Outcrossing has benefits, but as with all things, it also comes with a price. My blues used to be darker than most people's blacks, but I outcrossed to super-pale dilutes because I thought they were "pretty". It was generations later that I realized my colors were getting all washed out, even on the non-dilutes. I had obviously introduced some negative color modifiers (didn't know anything about that at the time), used the new stock to breed to all my rabbits (I had purchased some non-dilute rabbits from her as well), kept the kits from the early matings and used them as breeders, and didn't realize until generations later that the offspring never again were as dark.

Whether linebreeding or outcrossing or some combination thereof, it is important to carefully examine each potential breeder, and choose them because they are an improvement to your herd in some way. The quickest way to make improvement is to choose a single trait, and only keep stock that improves on that trait. If you try to select for a variety of things at once, overall progress still happens, but slower in any one given area.

For example, you might select a particular animal for outstanding fiber/fur, but they might be lacking in shoulder width or size/weight. By choosing to mate to a rabbit with outstanding body traits, but poor fiber, there is a chance you'll end up with a kit with the best of both worlds, good fiber and good body. There's also the chance you'll get the worst of both worlds, poor body and poor fiber, or any combination in-between. By only choosing kits from that mating that carry the traits you are looking for, either for your own herd or for sale, improvement will be made.

 

[savedbygrace979]

Linebreeding/inbreeding is more a succesfull yes/no depends on term used thing. We see the problems in certain groups of people where marrying cousins is common and has been happening for generations on end. Or the even closer family ties in some royal houses where brother - sister, niece - uncle and so on happend for max 4-6 generations before the whole family pretty much imploded from health problems, infertility and so on.
But somehow it is not a problem in animals. How much of that is truth and how much is not a problem traits that are ignored because show quality animal goal creates tunnel vision?
I just care about having healthy animals with inate good mothering skills giving 3-5 kits (5 preferred, but largest here is 7 from rex dwarf doe that is 5 years old now, was proven 5 and this is her second litter of 7 from 2 different bucks) and friendly/low stress behaviour. Coatcolors are fun, but i don't breed siblings for it. Might have to breed father to daughter due to buck shortage, but that litter will be for the freezer.
I know of another meatrabbit breeder who bought breeding stock from "good" breeder, they turned out small litters and weird problems and she later found out they where multigenerations of same litter matings.
I also hear a lot of show breeders finding small litters normal (1-3 kits for dwarf breeds). And i know fertility issues go with inbreeding. So I keep having a hard time believing the "it is not a problem" claims. It is blatantly obvious in many dogbreeds that the breedstandard stands in the way of health and welfare and there we know how inbred (and genetically tested free of the whole alphabet of whatever) they are. And even the fully tested animals have health issues like foodallergies, skin problems and so on.
So what is breeders blindness and what is truely not an issue?

The problem with inbreeding and linebreeding is that it's basically an old shortcut in breeding that has a positive short term outcome but a very negative long-term outcome if the practice is done continually. Before I went down the rabbit hole that is worldwide commercial breeding practices I didn't see any real issue with linebreeding because I didn't what all was involved nor what the long term consequences would be. However if you really want to see the long term consequences of linebreeding, just look at the rapid decline of the Holstein Cow breed. My money says that the entire breed of Holstein will be wiped out in 50 years because every single holstein cow alive is fathered by 1 of 2 bulls that have been dead for over 40 years. And to make matters worse no dairy cattle breeder will buy the semen of any of these 2 bull's male offspring because of the significant decrease in fertility and milk production of those lines. The Holstein breed was literally a inbred mutation that they artificially turned into a worldwide homogynous gene pool of millions and millions of cows. These two bulls that fathered the entire Holstein population had their semen milked daily their entire lives and has been artificially doled out to all the Holstein dairy producers due to the extremely significant increase in milk production by this line. Now decades later breeders are struggling to replace Holstein breed populations because these inbred children are having increased spontaneous abortions and miscarriages among other significant health/genetic issues...

Or you could dive down the rabbit hole that is our mutant chicken breeding of broiler hybrids that are incapable of breeding at all, and will randomly start dying after 16 weeks of age due to numerous health conditions...that's if their legs don't break on them at 10weeks old or they get "wooden breast" and are condemned to a compost pile after slaughter. Btw that's 6 billion of these mutant birds that get killed every year in america alone....

Take a dive down a rabbit hole and you won't come out the same...

 

[Alaska Satin]

The problem with inbreeding and linebreeding is that it's basically an old shortcut in breeding that has a positive short term outcome but a very negative long-term outcome if the practice is done continually. Before I went down the rabbit hole that is worldwide commercial breeding practices I didn't see any real issue with linebreeding because I didn't what all was involved nor what the long term consequences would be. However if you really want to see the long term consequences of linebreeding, just look at the rapid decline of the Holstein Cow breed. My money says that the entire breed of Holstein will be wiped out in 50 years because every single holstein cow alive is fathered by 1 of 2 bulls that have been dead for over 40 years. And to make matters worse no dairy cattle breeder will buy the semen of any of these 2 bull's male offspring because of the significant decrease in fertility and milk production of those lines. The Holstein breed was literally a inbred mutation that they artificially turned into a worldwide homogynous gene pool of millions and millions of cows. These two bulls that fathered the entire Holstein population had their semen milked daily their entire lives and has been artificially doled out to all the Holstein dairy producers due to the extremely significant increase in milk production by this line. Now decades later breeders are struggling to replace Holstein breed populations because these inbred children are having increased spontaneous abortions and miscarriages among other significant health/genetic issues...

Or you could dive down the rabbit hole that is our mutant chicken breeding of broiler hybrids that are incapable of breeding at all, and will randomly start dying after 16 weeks of age due to numerous health conditions...that's if their legs don't break on them at 10weeks old or they get "wooden breast" and are condemned to a compost pile after slaughter. Btw that's 6 billion of these mutant birds that get killed every year in america alone....

Take a dive down a rabbit hole and you won't come out the same...

Inbreeding/linebreeding are simply the practices of breeding closely related individuals to increase desirable traits and eliminate or reduce undesirable ones in a population. Defining and prioritizing traits to select in or out of the population varies with the species, the goals and the breeder. Inbreeding, even continually, is one tool among many that a producer can use to improve his herd. Like any practice, inbreeding/linebreeding can be done wisely or foolishly.

For example, quite a few of the Polish rabbits in our state have problems with malocclusion. We have used inbreeding/linebreeding to eliminate this trait in our herd. In culling rabbits that had or produced malocclusion, we reduced the number of both bucks and does available for breeding in the short term. However, this has produced a much healthier population. If we had continued to use all of the Polish rabbits available, to keep "genetic variation" high, this very undesirable trait would undoubtedly have remained or possibly increased in the population.

Further, inbreeding/linebreeding allowed us to identify the animals that carried the genes that produce malocclusion without expressing it. This would not have been possible without linebreeding. You can perhaps call this a shortcut, but it allowed discovery and correction in a time frame that was useful to us (and to the rabbits that were not thus born with malocclusion), rather than the trial-and-error of outcrossing that quite possibly may have never illuminated the situation.

But inbreeding does not necessarily mean never breeding any animal to an unrelated one. It does not necessarily mean using 2 male animals to produce most of the offspring in the next 40 years. I have never actually heard anyone suggest that a breeding program should start with two individuals and never bring any new blood into the line. We use linebreeding continually, but not exclusively. Most of us use inbreeding/linebreeding alternated with judicious outcrossing.

This is because outcrossing has its own perils. After four generations spent eliminating malocclusion, if we bring in an unrelated Polish that just happens to carry the genes that produce maloccusion, we have undone all of our work (and yet, we still benefit from the linebreeding we've done, because even now we know which animal produced the trait). The animal may also bring in many other undesirable characteristics. Sometimes the risk is worth taking, just as at other times the risks of inbreeding are worth taking. We used first linebreeding, and then outcrossing to Mini Satins, in our Polish. Sure enough, we are now working backward (i.e. linebreeding) to eliminate unwanted traits the Mini Satins introduced to our Polish line.

See, that's the thing - in livestock, genetic variability isn't an unqualified good thing. Genetic variation can include all sorts of undesirable genes, and reducing or eliminating them is generally a positive outcome, both short- and long-term. From an evolutionary/natural selection viewpoint, genetic variability is considered a good thing because it acts as a repository for traits that are currently maladaptive but may, in a changing environment, eventually become adaptive (note here that because the traits are currently maladaptive, the animals that carry and/or express those traits suffer and/or die). But this is a little nonsensical to argue in relation to the breeding of domestic rabbits; one breed may serve one purpose better than another, but it takes as little as a single outcross to import a new trait and inestimable genetic variation, if desired. Further, you can reduce, eliminate, or increase certain gene frequencies without reducing, eliminating, or increasing others. Ultimately, inbreeding/linebreeding doesn't necessarily reduce important variability; that depends on how big and how variable the population is to begin with, genetic linkages, the heirarchy of selective choices, and many other factors.

If you go back to the beginning, whether you subscribe to creation or evolutionary theory or a combination of the two, you may come to the conclusion that not just all breeds, but all species started out with very few individuals. Most genetic variation came about as a result of mutations; yet as far as geneticists know, the vast majority of mutations are not only maladaptive, but lethal...which is another thing that suggests that genetic variation, in itself, is not an unqualified good.

As far as the entire Holstein breed being wiped out, I do not share that concern. First, Holsteins are a breed of cattle selected and bred by humans for a specific reason, but I'm not sure the loss of a specific purebreed is cause for great anguish. There are numerous other breeds of cattle that can fulfill the purpose served by Holsteins (though perhaps not to the satisfaction of Big Ag). Second, there is some unknown number of small farmers, ranchers and homesteaders raising Holsteins and Holstein crosses. These animals - it is pretty much impossible to know how many are out there - are not included in the genetic analyses examining relatedness; and the crossbreeds, especially, may function as a tremendous resource for reinvigorating the breed. Finally, it takes relatively little outcrossing to restore genetic viability even in a significantly inbred population like Holsteins:

"Actually, it is easy to implement methods to maintain genetic (pedigree) diversity within a breed despite heavy use of genomic selection by simply limiting the influence of individual bulls and females that rank highest in the breed at any point in time. Spreading the pedigrees of young bulls across more bull and cow families than has been done over the past decade for Holsteins will result in very little, if any, loss of actual genetic gain over the long term." "The narrowing of the Holstein gene pool" by Les Hansen, Ph.D. in Dairy Cattle Genetics https://www.procross.info/wp-conten...ng-of-the-Holstein-gene-pool-July-2021-v2.pdf

I think the real problem you've identified in the Holstein and cornish cross chicken examples is greed, not inbreeding itself. Greed has resulted in myopic, very short-term views regarding breeding practices in big commercial operations. Thus, inbreeding (like many, many other practices in Big Ag) in these particular examples was done without much consideration for anything other than immediate profit. Multiple of these other unfavorable practices (e.g. excessive antibiotic use, overcrowding, unhealthy feed sources and feeding practices, to name just a few), in addition to careless inbreeding, have no doubt factored into the increase in significant health issues in Holsteins, chickens and other species farmed on an industrial scale (turkeys come immediately to mind as well). As Hansen notes in the same article linked above, "Genetic theory tells us short-term genetic gain should always be balanced alongside the potential for long-term genetic gain when developing strategies for genetic improvement of a breed." When that advice is ignored, both animals and people suffer as a result; and that argues for prudence in the practice of, rather than elimination of, linebreeding.

Big Ag's Holsteins and cornish cross chickens are good examples of inbreeding done foolishly. But I don't want to throw the baby out with the bathwater.

 

[savedbygrace979]

Those mutant chickens are not Cornish crosses they are hybrid broiler chickens and they shouldn't be alive. Same thing with the Holstein cows.

 

[kusanar314]

My money says that the entire breed of Holstein will be wiped out in 50 years because every single holstein cow alive is fathered by 1 of 2 bulls that have been dead for over 40 years.

So... I follow a dairy farm on FB that runs several hundred Holsteins and they use 7 or so different bulls every breeding group. They have a guy come through, he rates every cow in several different categories and then picks the best 7 or so bulls available that will correct any errors in the cows in the herd. So... yeah... not using "the same 1 or 2 bulls that have been dead for over 40 years" as you stated.

Or you could dive down the rabbit hole that is our mutant chicken breeding of broiler hybrids that are incapable of breeding at all, and will randomly start dying after 16 weeks of age due to numerous health conditions...that's if their legs don't break on them at 10weeks old or they get "wooden breast" and are condemned to a compost pile after slaughter. Btw that's 6 billion of these mutant birds that get killed every year in america alone....

I am confused, your rant seems to be about inbreeding being bad... however you bring a hybrid that rarely reaches sexual maturity into the discussion. Hybrid by it's very definition is not inbreeding, and if they never breed, they can't be inbred... BTW, if raised carefully they can actually be kept alive to sexual maturity and cross bred, it has been done by several people.

Those mutant chickens are not Cornish crosses they are hybrid broiler chickens and they shouldn't be alive.

Yes, they are Cornish X. Cornish X is a hybrid broiler chicken and is what they raise for commercial meat use. What do you think a Cornish X is if not a fat white bird that hits 5 lbs dressed weight in 6-12 weeks?

 

[RabbitsOfTheCreek]

Inbreeding/linebreeding are simply the practices of breeding closely related individuals to increase desirable traits and eliminate or reduce undesirable ones in a population. Defining and prioritizing traits to select in or out of the population varies with the species, the goals and the breeder. Inbreeding, even continually, is one tool among many that a producer can use to improve his herd. Like any practice, inbreeding/linebreeding can be done wisely or foolishly.
For example, quite a few of the Polish rabbits in our state have problems with malocclusion. We have used inbreeding/linebreeding to eliminate this trait in our herd. In culling rabbits that had or produced malocclusion, we reduced the number of both bucks and does available for breeding in the short term. However, this has produced a much healthier population. If we had continued to use all of the Polish rabbits available, to keep "genetic variation" high, this very undesirable trait would undoubtedly have remained or possibly increased in the population.

Further, inbreeding/linebreeding allowed us to identify the animals that carried the genes that produce malocclusion without expressing it. This would not have been possible without linebreeding. You can perhaps call this a shortcut, but it allowed discovery and correction in a time frame that was useful to us (and to the rabbits that were not thus born with malocclusion), rather than the trial-and-error of outcrossing that quite possibly may have never illuminated the situation.

But inbreeding does not necessarily mean never breeding any animal to an unrelated one. It does not necessarily mean using 2 male animals to produce most of the offspring in the next 40 years. I have never actually heard anyone suggest that a breeding program should start with two individuals and never bring any new blood into the line. We use linebreeding continually, but not exclusively. Most of us use inbreeding/linebreeding alternated with judicious outcrossing.

This is because outcrossing has its own perils. After four generations spent eliminating malocclusion, if we bring in an unrelated Polish that just happens to carry the genes that produce maloccusion, we have undone all of our work (and yet, we still benefit from the linebreeding we've done, because even now we know which animal produced the trait). The animal may also bring in many other undesirable characteristics. Sometimes the risk is worth taking, just as at other times the risks of inbreeding are worth taking. We used first linebreeding, and then outcrossing to Mini Satins, in our Polish. Sure enough, we are now working backward (i.e. linebreeding) to eliminate unwanted traits the Mini Satins introduced to our Polish line.

See, that's the thing - in livestock, genetic variability isn't an unqualified good thing. Genetic variation can include all sorts of undesirable genes, and reducing or eliminating them is generally a positive outcome, both short- and long-term. From an evolutionary/natural selection viewpoint, genetic variability is considered a good thing because it acts as a repository for traits that are currently maladaptive but may, in a changing environment, eventually become adaptive (note here that because the traits are currently maladaptive, the animals that carry and/or express those traits suffer and/or die). But this is a little nonsensical to argue in relation to the breeding of domestic rabbits; one breed may serve one purpose better than another, but it takes as little as a single outcross to import a new trait and inestimable genetic variation, if desired. Further, you can reduce, eliminate, or increase certain gene frequencies without reducing, eliminating, or increasing others. Ultimately, inbreeding/linebreeding doesn't necessarily reduce important variability; that depends on how big and how variable the population is to begin with, genetic linkages, the heirarchy of selective choices, and many other factors.

If you go back to the beginning, whether you subscribe to creation or evolutionary theory or a combination of the two, you may come to the conclusion that not just all breeds, but all species started out with very few individuals. Most genetic variation came about as a result of mutations; yet as far as geneticists know, the vast majority of mutations are not only maladaptive, but lethal...which is another thing that suggests that genetic variation, in itself, is not an unqualified good.

As far as the entire Holstein breed being wiped out, I do not share that concern. First, Holsteins are a breed of cattle selected and bred by humans for a specific reason, but I'm not sure the loss of a specific purebreed is cause for great anguish. There are numerous other breeds of cattle that can fulfill the purpose served by Holsteins (though perhaps not to the satisfaction of Big Ag). Second, there is some unknown number of small farmers, ranchers and homesteaders raising Holsteins and Holstein crosses. These animals - it is pretty much impossible to know how many are out there - are not included in the genetic analyses examining relatedness; and the crossbreeds, especially, may function as a tremendous resource for reinvigorating the breed. Finally, it takes relatively little outcrossing to restore genetic viability even in a significantly inbred population like Holsteins:

"Actually, it is easy to implement methods to maintain genetic (pedigree) diversity within a breed despite heavy use of genomic selection by simply limiting the influence of individual bulls and females that rank highest in the breed at any point in time. Spreading the pedigrees of young bulls across more bull and cow families than has been done over the past decade for Holsteins will result in very little, if any, loss of actual genetic gain over the long term." "The narrowing of the Holstein gene pool" by Les Hansen, Ph.D. in Dairy Cattle Genetics https://www.procross.info/wp-conten...ng-of-the-Holstein-gene-pool-July-2021-v2.pdf

I think the real problem you've identified in the Holstein and cornish cross chicken examples is greed, not inbreeding itself. Greed has resulted in myopic, very short-term views regarding breeding practices in big commercial operations. Thus, inbreeding (like many, many other practices in Big Ag) in these particular examples was done without much consideration for anything other than immediate profit. Multiple of these other unfavorable practices (e.g. excessive antibiotic use, overcrowding, unhealthy feed sources and feeding practices, to name just a few), in addition to careless inbreeding, have no doubt factored into the increase in significant health issues in Holsteins, chickens and other species farmed on an industrial scale (turkeys come immediately to mind as well). As Hansen notes in the same article linked above, "Genetic theory tells us short-term genetic gain should always be balanced alongside the potential for long-term genetic gain when developing strategies for genetic improvement of a breed." When that advice is ignored, both animals and people suffer as a result; and that argues for prudence in the practice of, rather than elimination of, linebreeding.

Big Ag's Holsteins and cornish cross chickens are good examples of inbreeding done foolishly. But I don't want to throw the baby out with the bathwater.

What an excellent explanation!

 

[savedbygrace979]

So... I follow a dairy farm on FB that runs several hundred Holsteins and they use 7 or so different bulls every breeding group. They have a guy come through, he rates every cow in several different categories and then picks the best 7 or so bulls available that will correct any errors in the cows in the herd. So... yeah... not using "the same 1 or 2 bulls that have been dead for over 40 years" as you stated.

Your friend is really the minority. 98% of the breed is fathered by 2 males. Those 7 or 8 "different bulls" are still great great great...grandchildren of the original 2. They have made efforts especially here recently to "fix" the breed but that is extremely difficult to do when 98% of diary farmers refuse to use anything other than the sperm of the 2 bulls that fathered the majority of the herd. Many dairy farmers have gone to using holstein crosses to avoid the bulk of the breeding problems in the Holstein line and yet keep milk production high.

How do you think they got to the point where they had a single cow that produced astronomically more milk than any others? Inbreeding and linebreeding to get those traits locked in at expense of the diversity of the species. What made this worse was now every dairy farm wanted sperm and stock from that magical bull. The rise of artificial insemination made that one bull's seed even more valuable...Hence where we are today with most of the breed fathered by this one bull and his most productive offspring. At the long term expense of the entire breed.

https://www.scientificamerican.com/article/from-two-bulls-nine-million-dairy-cows/
https://www.sciencedirect.com/science/article/pii/S0022030220302022
The "rant" on broiler chickens just further illustrated my point on the cows and the entire breeding operations of giant conglomerate corporations. And just to clarify here there are about 6 popular hybrid "broiler" chickens. The most popular of which is the Cornish Broiler not the Cornish Cross which is actually a sister species to the Cornish Broiler. These were created by crossing the Cornish with the Plymouth Rock. Now just for shits and giggles go ahead and try to mate one of those... They rarely live past 16 weeks because either their legs break due to excessive weight, or their heart or organs fail. They are sterile. But hey all this in the name of progress right?...

But hey, go ahead and keep on doing what everyone else is doing... why question anything, right??

Just because everyone else is doing something doesn't make it right. More and more data comes out each year showing how bad the breeding practices have gotten but since everyone still does it and nobody wants to stop......Shhhhhhhhhh........ don't talk about it...

 

[RabbitsOfTheCreek]

Your friend is really the minority. 98% of the breed is fathered by 2 males. Those 7 or 8 "different bulls" are still great great great...grandchildren of the original 2. They have made efforts especially here recently to "fix" the breed but that is extremely difficult to do when 98% of diary farmers refuse to use anything other than the sperm of the 2 bulls that fathered the majority of the herd. Many dairy farmers have gone to using holstein crosses to avoid the bulk of the breeding problems in the Holstein line and yet keep milk production high.

How do you think they got to the point where they had a single cow that produced astronomically more milk than any others? Inbreeding and linebreeding to get those traits locked in at expense of the diversity of the species. What made this worse was now every dairy farm wanted sperm and stock from that magical bull. The rise of artificial insemination made that one bull's seed even more valuable...Hence where we are today with most of the breed fathered by this one bull and his most productive offspring. At the long term expense of the entire breed.

https://www.scientificamerican.com/article/from-two-bulls-nine-million-dairy-cows/
https://www.sciencedirect.com/science/article/pii/S0022030220302022
The "rant" on broiler chickens just further illustrated my point on the cows and the entire breeding operations of giant conglomerate corporations. And just to clarify here there are about 6 popular hybrid "broiler" chickens. The most popular of which is the Cornish Broiler not the Cornish Cross which is actually a sister species to the Cornish Broiler. These were created by crossing the Cornish with the Plymouth Rock. Now just for shits and giggles go ahead and try to mate one of those... They rarely live past 16 weeks because either their legs break due to excessive weight, or their heart or organs fail. They are sterile. But hey all this in the name of progress right?...

But hey, go ahead and keep on doing what everyone else is doing... why question anything, right??

Just because everyone else is doing something doesn't make it right. More and more data comes out each year showing how bad the breeding practices have gotten but since everyone still does it and nobody wants to stop......Shhhhhhhhhh........ don't talk about it...

I can't tell if you're for inbreeding or against it

 

[kusanar314]

Your friend is really the minority. 98% of the breed is fathered by 2 males. Those 7 or 8 "different bulls" are still great great great...grandchildren of the original 2. They have made efforts especially here recently to "fix" the breed but that is extremely difficult to do when 98% of diary farmers refuse to use anything other than the sperm of the 2 bulls that fathered the majority of the herd. Many dairy farmers have gone to using holstein crosses to avoid the bulk of the breeding problems in the Holstein line and yet keep milk production high.

So... Thoroughbred horses have 3 foundation sires (males) that founded the entire breed, Morgans are descended from 1 stallion.

I fail to see how the descendants of 2-3 bulls is an issue since there is still genetic diversity since they are being crossed back and forth through many lines of cows.

The "rant" on broiler chickens just further illustrated my point on the cows and the entire breeding operations of giant conglomerate corporations. And just to clarify here there are about 6 popular hybrid "broiler" chickens. The most popular of which is the Cornish Broiler not the Cornish Cross which is actually a sister species to the Cornish Broiler. These were created by crossing the Cornish with the Plymouth Rock. Now just for shits and giggles go ahead and try to mate one of those... They rarely live past 16 weeks because either their legs break due to excessive weight, or their heart or organs fail. They are sterile. But hey all this in the name of progress right?...

So, what are you saying that a "Cornish Broiler" is? You have already said that they are hybrids, so that means that they are clearly Cornish crossed with something... which is exactly why they are commonly called "Cornish Cross" because the exact breeds and breeding strategy is protected and no one is 100% sure of the exact mix.

Yes, there are several different "blends" of Cornish Cross, depending on which hatchery they come from they will be slightly different but they are all the same basic animal.

Also, they are not sterile, and while they ARE delicate, they can be raised to sexual maturity, hens will lay eggs, roosters can fertilize hens with varying success (not due to fertility, due to their breasts being too big to line things up properly) and can be cross bred into a lighter meat bird. It has been done several several times by several people.

 

[eco2pia]

So, thing is, this can be a hot button topic for some people. Whether you line/inbreed or not comes down to personal preference, but scientifically it is sometimes called bottlenecking because a given population can come down to a skinny few number of individuals before being re-expanded. On a population wide scale, this is rarely a problem but it can be a big problem for an individual breeder. If you "know what you are doing" (I do, I am a research scientist and geneticist by training and trade) you can do this effectively MOST of the time. But there is some risk involved--there could be invisible traits (called "recessives") that you may unintentionally concentrate.

However, you can do that with every breeding you make, even unrelated individuals. You just have a higher chance of an unintentional negative outcome with related individuals, so you must be MORE VIGILANT about culling. It is not, in my opinion, morally right or wrong, it is a tool, like a chainsaw, that has the potential to do damage in inexperienced hands. I think the aspect which makes it controversial, is that sometimes it is used badly, by someone who is blind to the flaws in their own stock, until they have created a line of unhealthy animals. The odds are good that they would have made unhealthy animals anyway, it would have just taken more generations.

I have succesfully bottlenecked a line multiple times--it takes careful attention, and a LOT of space to re expand that line into a large pool of individuals again, which you MUST do--you need to keep many animals to adulthood and beyond, in case of late onset issues. I have also, even with the tools at my disposal to genotype animals directly from a blood sample, lost a line due to errors.

Fortunately it was not permanent, I could go outside my own operation to get new stock. But this is the point--As a casual breeder you should do this very, very, infrequently, if at all. And you should be prepared to fail--meaning you end up with a whole litter or even several litters that end up needing to be culled. If you eat your culls as I do, this may be ok, but if you do not, it is a very big problem.