Effect Measure

Poultry monoculture?

Public health scientists and professionals have human health and welfare at the center of our concerns. But we have learned that the human species is part of a tightly connected web of other living species and we are all roaming around in a common environment, the surface of the earth. Avian influenza is a good case in point. The influenza virus is mainly a parasite of birds but some forms also infect humans and some infect both. The influenza/A subtype designated H5N1 (“bird flu”) is a case in point. It devastates terrestrial birds, like poultry, and when it infects humans it has a truly horrific case fatality ratio, Ebola-like in magnitude and effect. But it’s not just the effect of the virus on us that is of public health concern. Poultry is one of the major sources of affordable protein throughout the world (including the US), and when you wipe out a poultry industry you have a major effect on nutrition. One of the major concerns about Genetically Modified crops is that the monopoly of seed stocks by large companies like Monsanto will lead to monoculture, a severely restricted genetic diversity that might make entire crops vulnerable to a disease adapted to a prevalent genetic make-up. It turns out that a team of experts from the US, China, The Netherlands and Canada have the same worries about the poultry “crop”:

As concerns such as avian flu, animal welfare and consumer preferences impact the poultry industry, the reduced genetic diversity of commercial bird breeds increases their vulnerability and the industry’s ability to adapt, according to a genetics expert.

Purdue University animal sciences professor Bill Muir was part of an international research team that analyzed the genetic lines of commercial chickens used to produce meat and eggs around the world. Researchers found that commercial birds are missing more than half of the genetic diversity native to the species, possibly leaving them vulnerable to new diseases and raising questions about their long-term sustainability.

“Just what is missing is hard to determine,” Muir said. “But recent concerns over avian flu point to the need to ensure that even rare traits, such as those associated with disease resistance, are not totally missing in commercial flocks.” (The Poultrysite)

This work was made possible because the entire chicken genome was published in 2004, the first bird to have its entire genome sequenced. In diploid organisms like chickens and humans, the genes are paired and the elements of the pair, the alleles, may differ somewhat or be the same. If they are identical there is no variation in that allele. According to the research team, commercial chickens have lost 90% of their alleles in comparison to native and non-commecial birds.

This is the same problem as the monoculture worry in non-animal crops. The standardization and drive for efficiency characteristic of industrial production has consequences.


  1. #1 Trent Wakenight
    November 24, 2008

    The concern about disease transmission between species is not going to go away. The transportation systems that we have created ensure that possibility.
    As reported on our Website, LocalActionGlobalHealth,
    – 60% of all infectious diseases transmit between species
    – Upwards of 75% move from animals to humans
    Just developing a poultry crop may be a narrow approach…Managing disease dilemmas is a multi-discipline, multi-sector, multi-industry concern and is the starting point for better management.

  2. #2 Susan Och
    November 24, 2008

    This doesn’t surprise me at all. I experimented with raising a commercial meat breed along with some heirloom breeds a few years ago. The difference was astounding.

    From the ground, it seems that what the commercial chickens were lacking was most of the cognitive skills of a chicken. They had no curiosity, they never scratched and they seemed basically unaware of anything beyond the food dish. Beyond eating until they fell asleep in the food dish, their range of behaviors was quite limited. I couldn’t let them out of the barn because they hadn’t the sense to run for cover if a hawk showed up.

    My heirloom breeds exhibit a wide range of personalities and behaviors, some of them unexpected and maddening. Some of them come up on the porch and watch us through the windows. Some, if allowed, will roost high in the trees. Most important in a poorer household, they will ignore the corn-based chicken food and go out, weather permitting, to scratch and forage for their own food. Our older breed chickens happily eat table scraps and give us eggs in return.

  3. #3 Brian Foley
    November 24, 2008

    Quite a bit of research on “meat breeds” vs “egg breeds” of chickens has been done in regard to the emerging problem of the subtype J of Avian Leukosis Virus.

    For example:

    Response of white leghorn chickens of various genetic lines to infection with avian leukosis virus subgroup J.
    Williams SM, Reed WM, Bacon LD, Fadly AM.
    Avian Dis. 2004 Jan-Mar;48(1):61-7.
    PMID: 15077798

    Detection and localization of naturally transmitted avian leukosis subgroup J virus in egg-type chickens by in situ PCR hybridization.
    Li N, Xu B, Dong W, Qiao S, Lee LF, Zhang HM, Li M, Du N.
    J Vet Med A Physiol Pathol Clin Med. 2007 Dec;54(10):553-8.
    PMID: 18045338

    Influence of strain, dose of virus, and age at inoculation on subgroup J avian leukosis virus persistence, antibody response, and oncogenicity in commercial meat-type chickens.
    Pandiri AR, Reed WM, Mays JK, Fadly AM.
    Avian Dis. 2007 Sep;51(3):725-32.
    PMID: 17992933

    The same issues are almost certain to apply to many other viruses, and perhaps some bacterial pathogens too. The bacteria can be more easily controlled with antibiotics than the viruses can.

  4. #4 K
    November 24, 2008

    In this area the PETA folks may be doing a grave disservice to humanity. Game bird breeders of course select for pugnacity but they also select for health and vigor. We have crossed some game blood into our domestic (non-commercial) breed flock. We have crossed about 15 varieties so much that many have only 1/128 of any one breed. We have stopped treating for Marek’s and avian pox. As a result our flock has high health. We seldom loose a chick to Marek’s anymore and haven’t had anymore avian pox. And as Susan says they are far more personable and interesting.

    PETA needs to lay off the game bird breeders. They are preserving valuable genes, the fighting may be abhorrent, but before the fight the males have a far better life than any commercial bird, and well they want to fight. The hens have a very good life. We don’t fight any birds or attend fights but we have been very happy with the chicken genes we got thanks to some breeders that do.

  5. #5 Susan Och
    November 25, 2008

    The American Livestock Breeds Conservancy has been preserving heirloom breeds of livestock for the past 30 years, by finding and identifying overlooked populations, finding farmers to act as stewards for these breeds, and then designing breeding plans to expand the populations.

    It’s no surprise that they have listed so many breeds of chickens. Chickens have traveled with humans to all climates and habitats and their fast reproductive cycle is easily manipulated to produce birds for every situation.

    Our ancestors spent many generations breeding a wide variety of livestock breeds. A “one purpose” animal was too expensive to keep — chickens were used for meat, eggs, pest control, for brooding, for fighting, as alarm clocks, and as companions. Perhaps we need to look at the traditional roles of livestock to find out “what’s missing” in the factory breeds. It seems foolish to toss out the work that our ancestors did just because we’re sure we don’t need it anymore.

    When corn is plentiful and transportation is cheap, it’s easy to think that Big Ag will always be there to provide for our food needs. But I’m afraid that factory farming is “too big to fail” just like the Big 3 automakers and the financial markets.

  6. #6 Susan Och
    November 25, 2008

    Oops, I forgot fertilizer. All livestock provides us with fertilizer, in the form of manure.

    Did you know that melamine is added to nitrogen fertilizer to make it release nutrients slower?

  7. #7 JJackson
    November 25, 2008

    It has always been a mystery to me why when domestic poultry get H5N1 the first action is to kill the flock. As there seems no chance of eradicating HPAI H5N1 I would have thought (given it did not increase the chance of spread) it would be best to leave any chicken that was not showing symptoms until it did. We need breeding stock and if any birds show resistance they should be treated as if they laid golden eggs.

  8. #8 K
    November 25, 2008

    J Jackson, I think that not culling all the flock would have been a good idea except that it is now so lethal that no one is willing to sustain the losses to find the few resistant birds and build up the flocks again. Likely if H5N1 hits the US all the possibly resistant birds in backyard flocks and game bird flocks will be culled to protect the commercial birds that probably are not resistant at all.

    So it goes

    Susan, Regarding heritage breeds I fear that to some extent they are or will become like breeds of dogs that get so inbred to sustain certain characteristics that vigor is lost. I am far more in favor of our backyard mutts – crossing breed back and forth (including at one heritage breed) has resulted in a progressively better flock year after year. If one preserves the vigor, and output of a breed while not worrying so much about color, comb type, etc all the physical identifiers that have nothing to do with vigor, then that I think is good. But our one heritage bird died young and did not add much to the flock while our leghorns, orphs, RIR’s etc and games have crossed well and given us a flock of long living, healthy birds. Besides since they all look different we know each one and its much more interesting than a flock of birds that all look alike.

  9. #9 Lora
    November 25, 2008

    *stands up and applauds Susan*

    Greetings, fellow heritage breed chicken owner!

    I keep Buttercups, standard Cochins, Welsummers, Barnevelders and a bunch of EEs as my laying flock, and some show quality Phoenix (Onagadori) for spoiled pets.

    K: It depends very much on where you get your heritage breeds from. McMurray actually does not keep their own birds, they receive shipments of hatching eggs and birds from individual breeders, who are of varying quality and disease vigilance. The larger hatcheries have frequent problems with shipping sick animals. There are a few hatcheries who are diligent about both breed preservation and genetic quality–Sand Hill Preservation leaps to mind.

    As far as the mutts go, I find my EEs are rather aggressive compared to the purebreds. They are dominant over even the largest Cochin roosters, attempt to escape more frequently, and bite more fingers. And they give me this creepy look, like, “I remember when I was a T. rex and you were but a cowering weasel, you hairless monkey.”

  10. #10 K
    November 26, 2008

    Lora, the tamest chickens we have are part Brazilian Game (now there is a bird that looks like T-Rex and to us they are magnificent looking). One (now gone) used to come when I called, let me reach down to pick her up and virtually purr when I held her. Our current tamest bird is also of that line. The full Brazilian Game roo did get a bit too aggressive for us so we gave him away, but his progeny crossed with various domestic birds are fantastic and generally the tamest we have in relating with us. The English game that we have crossed in is less so but none of our birds ever feels a threat to us – of course we “free range” on an acre enclosed by poultry netting so they don’t ever feel caged.

    By EE’s I presume you mean Americana’s sometimes called Easter Egg chickens. They do have a strange look (which we like) but ours vary. This year we crossed a banty with some Americana with a part Marans rooster (to get blue times dark red for deep green eggs). The mother is very laid back and the father is totally non aggressive. One chick is more Americana looking than the mom and a tough bird – pecks a bit when the food you are holding runs out, but just out of being a real go getter. Flys up on my arm to get treats but unlike my very tame game cross gets right back down and hunts for more. Her crop each night looks like a baseball. We are entranced with her excess of personality. I find personality and temperament to be only partly breed and partly individual.

    More importantly most of our “breed” birds dropped dead by 3 years, while the crosses we made from them regularly go 6 or 7 years still laying and we have one hen who is 12 this year and just stopped laying last year. We had a few exceptions in our breed birds – an ugly as hell White Rock whose blood is in many of our birds and whose progeny all thankfully are better looking than her. But good layers and long livers. And a grand old Buff Orphington who raised her last brood at age 7 and dropped dead the day she weaned them. Her blood also persists in the flock but in much more attractive form regarding color and shape.

    We occasionally get an outside breed bird these days from some local breeder (we have never bought from anywhere but local breeders but they may have bought from McMurray or others) to add new blood to our flock of about 100 and/or some new characteristic. We got four Marans hens a few years ago and they all dropped dead within 2 years but crossed to game and other blood our part Marans are giving us darker eggs and greater longevity. Crossing chickens is to us the greatest fun of all. Every year we have something new that we have never had before and no one else has either and after 13 years we are immensely pleased with our flock of mutts. We have so much variety that I can tell almost every bird of our 100 apart on first glance.

    Once you label a type of bird a breed to be preserved you immediately limit the gene pool. I think that is always a mistake.

  11. #11 K
    November 26, 2008

    Some additional info on “breeds” that came to mind this morning. What we know of as breeds of chickens are in fact all the results of people crossing other breeds to each other except for the first breeds produced by selection from jungle fowl. Sir Edward wrote a book in 1929, Poultry Breeding & Production, based on the best back tracking he could do to see how the breeds of the day were derived.

    A selection from the book is posted here concerning the 6 or so breeds that were used to create the “mutt” called a Favorelle that then became a breed

    More recently the Chantecler was a created “mutt”
    “The Chantecler was created by first crossing a Dark Cornish male with a White Leghorn female, and a Rhode Island Red male with a White Wyandotte female. The following season pullets from the first cross were mated to a cockerel from the second cross. Then selected pullets from this last mating were mated to a White Plymouth Rock male, thus producing the fowl as seen today. Although this produced a pure White Chantecler, Dr. J. E. Wilkinson of Alberta, Canada, decided to create a similar chicken with a color pattern more suited to range conditions, one whose color pattern would blend with its background. He crossed the Partridge Wyandotte, Partridge Cochin, Dark Cornish, and the Rose Comb Brown Leghorn, to create the Partridge Chantecler. The Partridge Chantecler was admitted into Standard in 1935.”

    Since such useful breeds were created by crossing multiple previous breeds together, I just don’t understand freezing them in time, calling them heritage and striving from small populations to preserve them as they are now. Wouldn’t it be better to take the best of the small populations of breeds and cross them with the best of other breeds and keep the heritage PROCESS of creating new breeds alive instead of freezing breeds in time and causing inbreeding??? What wonderful NEW breeds might be out there if we keep doing what humans have done throughout the history of domestic poultry – mixing over and over for the hybrid vigor and new traits that result.

    For us our “breed” is the Alabama Free Ranger – the only trait they have in common is that they are healthy vigorous free rangers and that is a joy.

  12. #12 Lora
    November 26, 2008

    K, my concern with preserving breeds vs. hybrid vigor is basically this: When you breed for hybrid vigor in a given environment, and the environment changes, some of those critters that may have been previously “weak” would have thrived in the new environment. Getting the original trait back from a mix is HARD and takes many generations. Even with a short generation time, there still might not be enough time to recover a sufficient population.

    Simple example: I live in a northern temperate climate with cold, snowy winters. Large breeds, feather-footed breeds do great here. Smaller poultry would croak without a heated coop, heated waterers, etc. However, over the past few years, winters have been getting milder and the summer of 2007 was absurdly hot and dry. I had to give the chickens ice blocks and frozen watermelons to keep them from overheating. Some folks around here got those mister-thingies installed–and this in an area where most houses do not have A/C. I’m thinking that in the future, banties and Mediterranean breeds might be a better choice in this area, and the heavy breeds will be best kept in Canada. Creating a bantam out of a mutt, though–that’s a lot harder than just maintaining some minimal number of banties in a specific microclimate and expanding the number of fertilized hatches, you know?

  13. #13 K
    November 27, 2008

    Naw Lora, creating a bantam by cross breeding is easy. You cross a hardy bantam (say a game bantam) to a larger bird – a bantam hen actually usually accommodates a large rooster fine because instead of sitting on her back they stand on the ground around her. Some of your offspring will be bantams some full size and some inbetween. Cross the bantam offspring back to your larger birds. Now statistically you have 3/4 of the orignal bird, 1/4 bantam but some will be bantam or mid size. Keep crossing back to your orignal birds until you have your original in bantam size but with all the other characteristics you want.

    But you miss my point – all your breed birds are mutts. Take the best of several breeds and cross them and you likely will get offspring with the fine characteristics that you desire from each. Keep selecting for those birds and pretty soon you will have a new breed!!! You won’t have lost what you wanted but combined the best of both or several – WHICH is exactly how those breeds were created. But now that their numbers are reduced and people want to freeze them in time there is a great risk of accumulating bad traits through inbreeding. If crossing birds is bad then all the breeds on the conservancy list must be bad as they are the result of crossing breeds.

    I live in Alabama – we don’t ever do anything to help out our birds in the summer – of course they are not shut up in a coop during the day. Sure they look hot panting out there in the sun but that is just how the cool off. Our coop is not entirely closed and they don’t have trouble when we drop below freezing either except for roosters with huge straight combs so we usually cull straight comb roosters unless they are outstanding in some other way. The few we have we put away from open windows and between several hens when it gets below 0.

    I really think some game blood in your flock would do more good than feathers on the feet. After all none of the wild birds with little bitty feet have feathers on them do they? I think the feathers just makes the humans feel better. But perhaps some of the inbred overbred (IMO) breeds are just not as tough as wild birds and mutts.

  14. #14 Susan Och
    November 27, 2008

    One of the things that pushed me towards heirloom breeds was this 2005 article about efforts to create one GMO chicken breed that would be resistant to avian flu, and then “depopulating” the world’s myriad chicken breeds and replacing them with the one “super chicken”. Each generation thinks that their own accomplishments represent the pinnacle of wisdom and that previous generations’ accomplishments are backwards or trivial.

    I admire the American Livestock Breeds Conservancy for their methods of using all available technology to understand and preserve genetic diversity in livestock. This article describes a study of DNA samples from old American breeds of swine, cattle, and goats, with a comparison to Spanish breeds. The results provide insight into history, and direction for conservation efforts.

  15. #15 K
    November 27, 2008

    Susan because I have the genes of at least 15 breeds distributed in our flock with most birds having 4 or more breeds as part of their genetic heritage, if one or more of those 15 breeds is resistant to Avian Influenza I will likely have a highly resistant flock. If someone has a flock of one type of heritage breed and that breed does not have resistance they will likely loose the whole flock. Since game birds are bred for vigor over meat or egg laying the addition of these lines to our flock IMO gives us the best chance to avoid AI. Of course likely they will all get culled anyway in the event of a breakout anywhere in the local area so I will never find out. But I can assure you that for us crossing the breeds has resulted in more healthy, longer living birds than the orignal breeds we began with.

    Lets conserve chickens by continuing the centuries long process of creating new breeds over and over by crossing old breeds and selecting for the best offspring. This is easier to do with chickens than other livestock as their are more old breeds around. But being stuck in time will dooms the breeds IMO.

  16. #16 K
    November 27, 2008

    My husband recommends this book if you can find it to increase understanding of just how chicken breeding is done to get desired traits

    Hagedoorn, A L, and Sykes, G. 1953. Poultry Breeding. London: Crosby Lockwood and Son.

  17. #17 K
    November 27, 2008

    This is written about spotted owl population but pertains


    One model of the minimum effective (or breeding) population required to prevent inbreeding depression and genetic drift is the 50/500 Rule. This rule states that an effective population (Ne) of 50 individuals is needed to prevent serious inbreeding depression, while an Ne of 500 is needed to guard against genetic drift (Nunney and Campbell 1993).

    I hope any who are trying to protect a heritage breed understand they either need a large number of birds preferably from several different breeders, or they need to regularly bring in new birds of the breed from different breeders.

    If you feel a breed has a trait to be preserved you have to also protect it from inbreeding – given that the populations of some of these birds are small it seems a difficult task unless you occasionally introduce some other breed and then breed back to retain the desired characteristics. In fact in the past this was done all the time until someone got the bright idea of standardizing breeds. Worse of course in dogs where an association actively prevents this vital way of eliminating the accumulation of bad genes.

    Sorry to be such a nag about this but I fear we could loose what good we have gained by freezing the breeds at one point in time rather than continuing the wonderful process that got them there to that point in time.

    I wonder, if I follow the documented program of breeding used to create the Chanticleer would I have a Chantecleer or a mutt???? What if I did just as those breeders did and got an even better bird. Would it still be a mutt inferior to the frozen in time Chanticleer???

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