InBreeding?

[AquaEyes]

Quote:
This is not a bad answer at all to the question; except that you narrowed it to exhibition folks. This is not correct. (If you were using them as an example, I wish you would have said so).

The chicken that is bought in the local grocery store is from some of the most highly inbred lines on the planet. Those lines (usually 3; sometimes 4) were then crossed to produce the resulting bird that is eaten.

The eggs bought from the local grocery store are produced by chicks also from 3 or 4 highly inbred lines. (The reason for the lack of taste has nothing to do with the inbreeding).

Cockers the world-over utilize and maintain highly inbred lines of birds.

Thus, whether we are talking commerical, exhibition, or game, the chickens that most affect the world are from highly Inbred Lines of Chickens.

I bolded the piece in my previous post which pertained to your comment.

 

[AquaEyes]

Quote:
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My experience is just the opposite. On those occasions when I have brought in new birds to begin a new project disease is an issue for the first few years. I do not medicate. Period. One of the factors I select for is disease resistance. Once I have established a line I no longer experience any problems with disease. That line of Red Bantams I often mentionas an example. I've bred them for 20 years now & I can't remember the last time one got sick.

Is the disease an issue because of the introduction of new genes, or a new bird? Chickens can be carrying disease pathogens without displaying symptoms, then begin shedding pathogens when stressed (such as when being brought into a new location). Two groups of birds, neither of which showed any symptoms of illness, can suddenly get sick when introduced to each other, as a result of sharing pathogens. Flock A was immune to getting sick from Illness 1, and Flock B was immune to getting sick from Illness 2. Introduce them, and Flock A gets sick from Illness 2, and Flock B from Illness 1. If they were maintained as separate lines on the same property but switched among pens, perhaps this wouldn't happen.

Disease resistance is not a permanent trait -- as diseases evolve, what was once disease-resistant can become susceptible to a new variant of the disease. If you bring the same line to a different area of the country with different pathogenic organisms, they might not be as disease resistant any more. Inbreeding becomes a double-edged sword -- you produce uniform-looking animals, but they also have uniform-looking immune systems. If a pathogen finds a way in to one chicken, it's got the keys to the whole flock. That's why commercial inbred lines keep up so much biosecurity.

 

[NYREDS]

Quote:
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My experience is just the opposite. On those occasions when I have brought in new birds to begin a new project disease is an issue for the first few years. I do not medicate. Period. One of the factors I select for is disease resistance. Once I have established a line I no longer experience any problems with disease. That line of Red Bantams I often mentionas an example. I've bred them for 20 years now & I can't remember the last time one got sick.

Is the disease an issue because of the introduction of new genes, or a new bird? Chickens can be carrying disease pathogens without displaying symptoms, then begin shedding pathogens when stressed (such as when being brought into a new location). Two groups of birds, neither of which showed any symptoms of illness, can suddenly get sick when introduced to each other, as a result of sharing pathogens. Flock A was immune to getting sick from Illness 1, and Flock B was immune to getting sick from Illness 2. Introduce them, and Flock A gets sick from Illness 2, and Flock B from Illness 1. If they were maintained as separate lines on the same property but switched among pens, perhaps this wouldn't happen.

Disease resistance is not a permanent trait -- as diseases evolve, what was once disease-resistant can become susceptible to a new variant of the disease. If you bring the same line to a different area of the country with different pathogenic organisms, they might not be as disease resistant any more. Inbreeding becomes a double-edged sword -- you produce uniform-looking animals, but they also have uniform-looking immune systems. If a pathogen finds a way in to one chicken, it's got the keys to the whole flock. That's why commercial inbred lines keep up so much biosecurity.

Let me try to clarify: On those instances when I have brought in new birds disease has been a problem for the first few generations in the new birds. I assume because of susceptibility to existing pathogens. New birds have not infected my existing flocks.
As to permanence I don't know how long that is but as stated my 20 year line-bred flock of R I Red Bantams simply doesn't get sick any more. I hear what you're saying about variant organisms but as yet I haven't run into that problem. These birds are intermingled with birds from other parts of the country when they go to shows and as yet no negative results of this contact. As I have previously stated I do not quarantine birds when they return from a show. I have sold birds to people all over the US with no reports of resulting disease problems in the birds they have purchased.
With all due respect, you're basing your comments on things you've read. I'm basing mine on things I've done.

 

[Chris09]

Quote:
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My experience is just the opposite. On those occasions when I have brought in new birds to begin a new project disease is an issue for the first few years. I do not medicate. Period. One of the factors I select for is disease resistance. Once I have established a line I no longer experience any problems with disease. That line of Red Bantams I often mentionas an example. I've bred them for 20 years now & I can't remember the last time one got sick.

Is the disease an issue because of the introduction of new genes, or a new bird? Chickens can be carrying disease pathogens without displaying symptoms, then begin shedding pathogens when stressed (such as when being brought into a new location). Two groups of birds, neither of which showed any symptoms of illness, can suddenly get sick when introduced to each other, as a result of sharing pathogens. Flock A was immune to getting sick from Illness 1, and Flock B was immune to getting sick from Illness 2. Introduce them, and Flock A gets sick from Illness 2, and Flock B from Illness 1. If they were maintained as separate lines on the same property but switched among pens, perhaps this wouldn't happen.

Disease resistance is not a permanent trait -- as diseases evolve, what was once disease-resistant can become susceptible to a new variant of the disease. If you bring the same line to a different area of the country with different pathogenic organisms, they might not be as disease resistant any more. Inbreeding becomes a double-edged sword -- you produce uniform-looking animals, but they also have uniform-looking immune systems. If a pathogen finds a way in to one chicken, it's got the keys to the whole flock. That's why commercial inbred lines keep up so much biosecurity.

You have to also understand that animals will evolve also, and if the animal is strong enough and healthy enough that animal can cope with if not grow a immunity to a disease.
If you eliminate the bird/ birds that can not cope with or grow a immunity to a disease then over a period of time you will have a "superior" flock that will have the ability to resist most disease.

Chris

 

[saladin]

Quote:
yikes. is this common? is that what people mean when they say to be "prepared to heavily cull"?
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No, I'd say its not "common" in lines that have been managed properly. Heavily inbred lines (I believe there's a difference between that and line-bred), yes, things like this will/can pop up a lot.

When people say "prepared to heavily cull" it can be for different reasons. So, if you want better egg laying, cull the poor egg layers. If you want disease resistance, don't breed birds that get sick. If you want your birds to be up to standard, be prepared to cull, cull, cull to get them there. It's all-the-above for me.

I would agree with punky wholeheartedly. I have almost no deformities of any kinds. If the birds you are breeding have recessives for deformities then, yes, they will show up.

Usually what is most often seen with intense inbreeding for several generations is either a lack of vigour, a drop in egg production or infertility. However, this does not have to be the case if proper selection has been taken care of.

For example, with Games, it is a common practise to breed a cock to his daughter, granddaughter and great-granddaughter and then breed the great-great granddaughter to another related cock (known as 3 times in 1 time out). Personally, I prefer breeding Uncle x niece or half-brother x half-sister (these usually are from the same sire but different hens).

I was taught that you can breed brother x sister, but to only do it once every 7 or 8 generations. Some practise brother x sister matings more often than that, but I do not.

The old traditional farm method of chicken breeding, known as Rolling Matings, is actually a form of linebreeding. With this method and proper selection a line could be carried on indefinately with no negative results. I am convinced of that.

Though chickens aren't people, it is always nice to remember that the famed Cleopatra with the result of 8 generations of either brother x sister or uncle x niece unions.

 

[saladin]

Quote:
This is not a bad answer at all to the question; except that you narrowed it to exhibition folks. This is not correct. (If you were using them as an example, I wish you would have said so).

The chicken that is bought in the local grocery store is from some of the most highly inbred lines on the planet. Those lines (usually 3; sometimes 4) were then crossed to produce the resulting bird that is eaten.

The eggs bought from the local grocery store are produced by chicks also from 3 or 4 highly inbred lines. (The reason for the lack of taste has nothing to do with the inbreeding).

Cockers the world-over utilize and maintain highly inbred lines of birds.

Thus, whether we are talking commerical, exhibition, or game, the chickens that most affect the world are from highly Inbred Lines of Chickens.

I bolded the piece in my previous post which pertained to your comment.

I understand you line of thinking, I just don't completely agree. Whether it is with breeding to the Standard or Games, the hope is for improvement with each generation. Otherwise, there would be not challenge. The exhibition breeder and the cocker are always seeking to better the fowl they have in their hands. I would dare say, the commercial breeder desires the same.