What exactly does breed for resistance mean?

[NYREDS]

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[gogoalie]

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No, you're missing an important point. When they get sick they're not allowed to "recover or die", they're culled. Even if they were to recover they'd still be genetically predisposed to the particular disease. Obviously other birds in the flock would also have been exposed to the particular pathogen. The ones that don't get sick are the ones you keep to breed from.

So then, how did the ones that didn't get sick from exposure, get that way? From parents that survived the preivous sickness, & passed on it's surviable genese, the ones that died, can't! Again, if you cull the ones that ARE sick, & you don't give them a chance to recover, yer just artificially selecting bad genes...lets say, 9 outta 10 that you would've culled, died, & only one survive, if you allow that one to breed, from another survivor group & the same sickness exposes to it's progeny, you'll probably have 3 outta 10 survive & then their offspring will have more capable immune system to produce a more roubust progeny.

 

[DAFox]

I am having my first outbreak of some form of CRD -- I suspect MG or MS. I found 2 birds on the same day with swollen sinuses, nasal discharge (no smell), and "bubbly" eyes. After doing some research, I decided to leave these birds with the flock to intentionally infect susceptible birds while at the same time treating the whole flock with antibiotics. This is my theory -- the antibiotics will help some exposed birds resist the infection. Antibodies might develop without having these birds become carriers. Those that do get sick will be culled -- or some may be quarantined behind 2 fences (because I have a darn soft spot which I am trying to get rid of).
The course of antibiotics will go on for a month or so. If the outbreak continues after the antibiotics, those sick birds will be culled or quarantined. No more antibiotics will be given. After another month or so of no illness, I will invite the State Vet to test all remaining birds, if I have any. Carriers will be culled or quarantined. I think after several months of practicing excellent biosecurity between MG/MS positive birds and those that might be negative, I'll lose the soft spot and will be able to cull the positve birds. I am hoping to create a resistant flock from this experience.
Because this is a "middle of the road" option, I can still decide to "close" my flock forever and allow carriers to remain with the flock or I might decide in a month to cull everyone and start over.
I might have brought it home from the feed store or a swap or had a carrier for awhile. I don't know. I am doing my best not to infect others by wearing clean clothes, cleaning my shoes and hands with an antibacterial disinfectant when I leave. No birds or eggs will be sold.
Dale-Ann

 

[gogoalie]

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WHo has suggested culling birds that aren't sick?

Lemme reclarify for you then, please:

"Immediate culling (of SICK birds) from the flock, of those that aren't sick, is just artificial selection." Dunno why you'd imply that I am implyin' that you can cull NON sick birds...(shakes head....)

 

[DAFox]

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No, you're missing an important point. When they get sick they're not allowed to "recover or die", they're culled. Even if they were to recover they'd still be genetically predisposed to the particular disease. Obviously other birds in the flock would also have been exposed to the particular pathogen. The ones that don't get sick are the ones you keep to breed from.

So then, how did the ones that didn't get sick from exposure, get that way? From parents that survived the preivous sickness, & passed on it's surviable genese, the ones that died, can't! Again, if you cull the ones that ARE sick, & you don't give them a chance to recover, yer just artificially selecting bad genes...lets say, 9 outta 10 that you would've culled, died, & only one survive, if you allow that one to breed, from another survivor group & the same sickness exposes to it's progeny, you'll probably have 3 outta 10 survive & then their offspring will have more capable immune system to produce a more roubust progeny.

A bird that has resistance to disease may have a strong immune system from good genes or great nutrition. A bird that survives an infection is just lucky. I don't know if antibodies can be passed to the egg, but some infections can.
Dale-Ann

 

[gogoalie]

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So then, how did the ones that didn't get sick from exposure, get that way? From parents that survived the preivous sickness, & passed on it's surviable genese, the ones that died, can't! Again, if you cull the ones that ARE sick, & you don't give them a chance to recover, yer just artificially selecting bad genes...lets say, 9 outta 10 that you would've culled, died, & only one survive, if you allow that one to breed, from another survivor group & the same sickness exposes to it's progeny, you'll probably have 3 outta 10 survive & then their offspring will have more capable immune system to produce a more roubust progeny.

A bird that has resistance to disease may have a strong immune system from good genes or great nutrition. A bird that survives an infection is just lucky. I don't know if antibodies can be passed to the egg, but some infections can.
Dale-Ann

& Those strong genes came from birds that survived the sickness that it is resistant to.

 

[DAFox]

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A bird that has resistance to disease may have a strong immune system from good genes or great nutrition. A bird that survives an infection is just lucky. I don't know if antibodies can be passed to the egg, but some infections can.
Dale-Ann

& Those strong genes came from birds that survived the sickness that it is resistant to.

I need to understand what you are saying. Are you saying that because a bird survived a disease, its genes changed so that its prodigy will be resistant to the same disease? If this is what you mean, then I believe you are mistaken. Genes don't mutate because of a situation. Genes mutate randomly. If the mutation is beneficial in a particular situation, it gets passed on because it allows the organism to survive and propagate better than its peers in the same situation.
What I need to research is if antibodies can be passed into the egg from a hen who has survived a disease. Antibodies can help an organism resist a disease. I know that some diseases can be passed to the egg and infect a chick.
Dale-Ann

 

[gogoalie]

Well, obviously something would've changed in that bird that survives, produces offspring that will survive...it could be a genetic mutation within microscopic regcognition of helper T cells (or Killer T cells, I can't quite remember) in recognizing that said pathogen that has invaded the body, & then expressing the histamine that releases the bodies immuno response system. That small mutation can & will be passed onto the progeny of the progenator that survives an outbreak of a deadly pathogen, so that when an outbreak occurs again, it will not get sick, or if it does, just shows symptoms, & won't be affected, to a greater extent. The ones that don't have the immuno supressive trait or gene, or whatever you want to refer to it as, will die so will their progeny...so, if you cull the ones that might recover, & pass on that mutation, then you've weakend yer gene pool.

 

[speckledhen]

Someone whose idea of breeding for resistance being allowing sick birds to recover, with or without treatment, is someone I do not want selling to me or anyone else on BYC. We hear enough complaints about sick birds making the buyer's flock ill. Nobody ever does actual testing to see if the birds they want to sell are carriers of whatever they had, so there is no way to be sure it won't be setting up heartache in someone else's flock.

I am 100% in agreement with NYReds: Recovered carrier birds are not strong, they are not resistant (unless you're talking something minor like fowl pox and not actual respiratory stuff), and they will make birds in their new flock come down with the same thing eventually. Some avian diseases are like the herpes/HIV virus-they never leave the body even when the bird appears healthy. Remember Typhoid Mary?

 

[kathyinmo]

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UGGGG .... I always hated Microbiology.