Table of Contents:

Foreword

Introduction

I. Storm Gathering

1. 1918

2. Master of Metamorphosis

3. H5N1

4. Playing Chicken

5. Worse Than 1918?

6. When, Not If

II. When Animal Viruses Attack

1. The Third Age

2. Man Made

3. Livestock Revolution

4. Tracing the Flight Path

5. One Flu Over the Chicken's Nest

6. Coming Home to Roost

7. Guarding the Henhouse

III. Pandemic Preparedness

1. Cooping Up Bird Flu

2. Race Against Time

3. Tamiflu

IV. Surviving the Pandemic

1. Don't Wing It

2. Our Health in Our Hands

3. Be Prepared

V. Preventing Future Pandemics

1. Tinderbox

2. Reining in the Pale Horse

Topics

References 1-3,199

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Unnatural growth rates can lead to crippling deformities

According to a textbook on avian virology, “Viral infections can move fastest through groups of birds maintained in closed, crowded, unsanitary conditions.”1810 Under such conditions, even healthy immune systems might be overwhelmed, but immune competence among modern poultry breeds may be at an all-time low. Breeding for production traits, like increased breast muscle in meat-type birds or increased egg-laying in egg breeds, seems to necessarily mean breeding for decreased immune function. Given the intensive breeding-out of immune functionality, almost all modern commercial chickens may be “physically compromised” in a way that would facilitate wild waterfowl viruses taking hold. “[D]omestic poultry have been bred to be plump and succulent rather than disease-resistant,” a senior virologist at the Australian Animal Health Laboratory points out. “[T]hey’re sitting ducks, so to speak, for their wild cousins’ viruses.”1811

It wasn’t until well into the 20th century that the poultry industry began segregating chicken breeds—some for meat and others for eggs.1812 Once maximum productivity became the emphasis, these two traits became mutually exclusive. For broilers, “meat output per chick” is considered the most important goal,1813 so the bigger the better.1814 In contrast, the industry wants laying hens to be small. Big eggs from small bodies ensures that more of the feed goes into the egg rather than being “wasted” on the upkeep of the rest of the animal.1815

In the egg industry, “feed conversion,” the conversion of feed into eggs, is considered the trait with the single biggest “impact on profitability.” Modern egg-laying hens are bred to be so scrawny that it’s not profitable to raise male chicks for meat. Since they can’t lay eggs, male chicks are an unwanted by-product of the industry. It makes more economic sense to kill the male chicks shortly after hatching by the hundreds of millions1816 —grinding them up alive, gassing them, or throwing them into a dumpster to suffocate or dehydrate1817 —than to waste feed on them.1818

So, in the interest of maximizing productivity, two different lines of chickens were created, one for meat and another for eggs. As one historian noted, by the end of the 1950s, the “era of the designer chicken” had arrived.1819 The results have been extraordinary. Selective breeding over time is, after all, what turned the wolf into a poodle. Ancestors to the modern-day chicken laid only about 25 eggs a year.1820 Today’s laying hens produce more than ten times that number,1821 leading to increasing problems with uterine prolapse1822 and broken bones due to critical weakening, as skeletal calcium is mobilized to form shells for the eggs.1823

The “essence”1824 of broiler chicken production, as poultry scientists describe it, is “turning feed stuffs into meat.”1825 Chicken ancestors grew to be about two pounds in four months.1826 In the 1950s the industry could raise a five-pound chicken in less than three months. Due mostly to selective breeding (in addition to growth-promoting drugs), this now takes an average of 45 days.1827 Broiler chickens now grow more than twice as large in less than half the time. To put the growth rate of today’s broiler chickens into perspective, the University of Arkansas Division of Agriculture reports, “If you grew as fast as a chicken, you’d weigh 349 pounds at age two.”1828 In one century, as one historian relates, “the barnyard chicken was made over into a highly efficient machine for converting feed grains into cheap animal-flesh protein.”1829

Interestingly, this transformation in chickens was considered such an “outstanding example of the contribution of breeding work”1830 that many of the earliest poultry scientists helped form the American Breeders’ Association,1831 which went on to lead the human eugenics movement.1832 Leading U.S. poultry scientist and eugenics pioneer Charles B. Davenport spoke of poultry breeding efforts as akin to “race improvement”1833 and “purification.”1834 Likewise, Heinrich Himmler’s experience with chicken breeding has been noted for having shaped his views on the subject.1835

The “improvement” of poultry over the last century has been deemed “quite profitable,”1836 but the industry admits to the downsides. The current editor of industry trade journals WATT PoultryUSA and the Poultry Tribune wrote, “Ongoing efforts to increase breast-meat yield, for example, have created a higher propensity for musculoskeletal problems, metabolic disease, immunodeficiency, and male infertility, primarily because the extra protein going to breast muscle production comes at the expense of internal organ development.”1837

Today’s broiler chickens grow so fast that they outpace their cardiovascular system’s ability to keep up, leading to forms of heart failure like Sudden Death Syndrome (also known as “flip-over syndrome”). Heart failure is an increasingly1838 major1839 cause of mortality among commercial flocks, even though the birds are only a few weeks old. An industry journal reports that “broilers now grow so rapidly that the heart and lungs are not developed well enough to support the remainder of the body, resulting in congestive heart failure and tremendous death losses.”1840

Mortality rates of broilers are up to seven times that of chickens not bred for fast growth.1841 This tradeoff is accepted if the increased mortality is compensated for by an increase in meat yield or feed conversion. To maximize profits, commercial broiler producers now accept a mortality rate of 5%.1842

Chickens aren’t dying just because their circulatory systems are collapsing under the strain. Chickens bred for unnaturally developed muscles (meat) have unnaturally underdeveloped immune systems. Broiler chickens selected for accelerated growth suffer from weakened immunity, which increases mortality1843 by making them “more susceptible to a variety of infectious diseases.”1844 When you breed for one characteristic, you may lose another. The modern tomato, for example, may be perfectly round and survive to market less bruised, but it also may be tough, pink, and tasteless compared to heirloom varieties. Just as purebred poodles tend to have problems with their hips, modern-day purebred chickens tend to have problems with their immune systems.

Even excluding heart failure, studies show that the highest mortality is seen in the fastest-growing chickens, and the lowest mortality in the slowest-growing chickens. Researchers conclude, “It appears that broilers with faster growth rate are under physiological and immunological stress that makes them more sensitive to infectious diseases….”1845 This has been shown for both viral1846 and bacterial1847 pathogens. In one study, broilers were intentionally infected with E. coli: 40% of the fast-growing heavier birds died, compared to only 8% to 20% mortality for slower-growing breeds. The scientists commented, “These results indicate that rapid growth rate substantially reduces broiler viability.”1848

Research with turkeys shows the same thing, despite the president of the National Turkey Federation’s claim that “[r]ealty [sic] is that in this country the poultry industry treats the health of the birds as the number one issue.”1849 Lighter and slower-growing turkey breeds than those conventionally used have better immune performance1850 and are hence more resistant to stress1851 and disease.1852 Researchers have observed that in natural outbreaks of disease like fowl cholera,1853 turkeys bred for increased egg production and those selected for increased body weight had significantly higher mortality rates.1854 Slower-growing, lighter breeds of turkeys also have greater adaptability to the stresses associated with production, such as overcrowding.1855 USDA researchers at the University of Arkansas went so far as to suggest in a 2005 paper in Poultry Science that “fast growth in modern turkey lines” may result in stress responses “incompatible with the severe stressors that sometimes occur during commercial poultry production.”1856

The turkey industry has so altered the natural order that the enormous breast meat mass of commercial breeds has resulted in the birds being physically incapable of mating.1857 “One hundred percent artificial insemination,” researchers note in Livestock Production Science, “allowed for the continuation of intense selection for body weight in male lines.”1858 Female turkeys are inseminated by tube or syringe.1859

Selection has been so intense that commercial turkeys, like broiler chickens, can barely support their own weight. A staff editor of the leading U.S. livestock feed industry publication writes that “turkeys have been bred to grow faster and heavier but their skeletons haven’t kept pace, which causes ‘cowboy legs.’ Commonly, the turkeys have problems standing…and fall and are trampled on or seek refuge under feeders, leading to bruises and downgradings as well as culled or killed birds.”1860 One group of researchers concluded, “We consider that birds might have been bred to grow so fast that they are on the verge of structural collapse.”1861

Many do collapse and spend much of their time lying in their own waste. Similar to broiler chickens, most turkeys in commercial production are overcrowded in warehouse-like sheds, and the majority1862 suffer from ulcerative contact dermatitis, from breast blisters to bed sore-like hock burns.1863 These painful lesions add to the stress that may impair overall immune performance. USDA researchers conclude: “Selection of poultry for fast growth rate is often accompanied by a reduction in specific immune responses or increased disease susceptibility.”1864

Slower growth is costly, but so are disease outbreaks. Why doesn’t the industry select for birds with improved immune responses? They’ve tried. Early in the industry’s history, rather crude methods were used to try to breed for resistance. Breeders would take baby chicks and challenge their immune systems by exposing them to adults with Marek’s disease, a poultry disease caused by a cancer-causing herpes virus. Those who lived through the exposure went on to create the next generation, one that would presumably be more resistant to the disease.1865 No one wants to bite into a tumor at KFC.

Sometimes the chicks didn’t get infected by casual exposure, though. Breeders found that by dripping virus-laden blood from infected chickens into the eyes of baby chicks, they were able to guarantee infection, but this produced mortality rates between 30% and 60%. It was not considered economical to kill more than half the chicks. “Challenge by intraperitoneal injection of whole blood or suspensions of fresh tumorous gonads from clinically sick birds was also tested,” poultry scientists report, “but later discontinued because the mortality rates exceeded the optimum of 50%….” The intent was to kill off half the chicks, but injecting ground-up tumorous sex organs into the abdomens of baby chicks turned out to be a little too fatal.1866

Challenge tests continue in poultry bree1867ding, but on a much smaller scale. This kind of direct selection is considered “inconvenient” in intensive production systems due to the costs involved.1868 Breeders have tried selecting for antibody response directly, but poultry scientists have found that those with the best antibody responses consistently had significantly lower weights at all ages.1869 Research dating back 30 years shows that chickens bred to be disease-resistant have lower body weight and produce smaller eggs.1870 Studies suggest that immune defects may actually enhance poultry performance.1871 Seems like you can have one or the other, immunity or growth. And the industry chooses growth.

This happens across species. Growth and disease susceptibility have been shown to go hand-in-hand in pigs,1872 cattle,1873 and dairy cows. Over the past century, genetic manipulation of dairy cows through selective breeding has tripled the annual milk yield to 18,000 pounds of milk per cow. It took the first half of the century to force the first ton increase, but since the 1980s, the industry has managed to add extra tons every eight or nine years.1874 Turning cows into milk factories has taken a toll on their immune systems,1875 increasing their risk of mastitis,1876 infections of the udder. Mastitis may be painful for the animal and spike the milk supply with increasing levels of somatic (pus) cells, but decreased cow immunity, as opposed to decreased chicken immunity, is unlikely to aid and abet in the killing of millions of people.

Why is immunity reduced when production is maximized? Our best understanding is the “resource allocation theory.” There is only a certain amount of energy, protein, and other nutrients coming into an animal’s system at any one time. Those resources can go to build muscle or to host defense, like a national budget in which money is divided between the country’s infrastructure and homeland security. So dairy cows, for example, have been bred to “redirect resources from the maintenance of an adequate immune system to milk production in order to maintain advantages in milk yield,” reads one dairy science textbook.1877 This is a trade-off between production traits and immunocompetence.1878

Studies show that old-fashioned, slower-growing chicken breeds have larger1879 and better developed1880 antibody-producing immune organs. Instead of being bred to transfer the bulk of resources to build breast meat while neglecting other needs, these slower-growing breeds had sufficient resources to foster a more functional antibody response system.1881 Antibodies are critically important for vaccine effectiveness, particularly in animals like broiler chickens who are killed after only a handful of weeks of life and don’t have time to acquire a set of their own immune memories. “Those animals which are intensively reared and slaughtered young,” notes one agricultural microbiologist, “will have the greatest potential for carrying pathogens.”1882

One of the reasons that 1% to 4% of broilers die from “acute death syndrome”1883 (in which chickens suddenly lose their balance, violently flap their wings, go into spasms, and die of acute heart failure) is that the metabolic demand for oxygen created by the increasing muscle mass leaves the rest of their body short of oxygen.1884 Forget immunity—many modern broiler chickens can hardly keep up with breathing. Meat-type birds outgrow their lungs, hearts, and immune systems.

The maintenance of an effective immune system is metabolically very costly.1885 The “big eater” macrophage immune cells burn through almost as much energy as maximally functioning heart muscle.1886 Antibodies are made out of protein. When the body is churning out thousands of antibodies per second, there is less protein available for growth. Studies show that chickens capable of mounting a decent antibody response have lower weight and lower weight gain than chickens with suboptimal antibody production.1887

Germ-free chicks raised in germ-free environments grow faster than chickens in unsanitary environments.1888 Even minute exposures to the normal microbial flora of the gut are enough of an immune stimulus to significantly reduce growth rates.1889 Though there’s no tissue damage and no evidence of disease, just the normal day-to-day functioning of the immune system diverts energy from maximal growth.1890 That’s why you can feed germ-free chickens in a sanitary laboratory environment all the antibiotics you want and there will be no change in growth rates, whereas commercially confined chickens fed antibiotics demonstrate a remarkable spurt in growth.1891 By breeding for maximum production, the industry seems to be breeding for minimum immunity.

The reason that selecting for growth impairs immunity is the same reason that human AIDS and tuberculosis patients waste away. Fighting off infection requires a remarkable demand for energy and nutrients. The body shifts resources away from nonessential anabolic (meaning growth, as in “anabolic steroids”) and maintenance processes toward bolstering life-or-death defenses.1892 This redistribution of resources makes sense from an evolutionary point of view. What use is long-term growth when short-term survival is threatened? Not only are the body’s construction projects halted, but they start to be torn down for raw materials. People with severe infections can lose up to one-third of their body weight as the body starts eating away at itself to feed more fuel into the immune machine.1893

Even relatively insignificant challenges to the immune system can significantly affect growth. Simple vaccinations can result in a greater than 20% decline in daily weight gain for farm animals and increase protein demands as much as 30%,1894 demonstrating the perverse balance between growth and immunity. The poultry industry can’t have it both ways.

Before domestication, natural selection chose strong immune systems for survival.1895 After domestication, though, “[a]rtificial selection concentrated on improvement of production traits with little attention to resistance to disease,”1896 reads one poultry breeding textbook. The industry seems more interested in the survival of the fattest, not the fittest.1897

Animals are preprogrammed by evolution to grow at the near optimal rate. The faster a juvenile animal grows to maturity in the wild, the faster he or she would presumably be able to win out over competing suitors to mate and produce more offspring. This would tend to select for maximum growth rates, but resource allocation is not the only reason Mother Nature puts on the brakes. Even in a germ-free environment, cells cannot divide and grow while simultaneously performing at peak efficiency.

Faster-growing fish, for example, swim less efficiently than slower-growing fish.1898 Faster-growing rainbow trout have been shown to have significantly impaired swimming performance.1899 The critical swimming speed of salmon genetically engineered to grow more than twice as fast by length as control fish is only half the speed of control fish.1900 Not only do broiler chickens bred for accelerated growth have smaller immune organs, but what little immunity they do have may not be functioning effectively.

The budgetary analogy, therefore, is imperfect. It’s not that there’s just a certain amount of resources to go around and every dollar spent on infrastructure is a dollar not spent on defense. It’s worse than that. By forcing broiler chickens to divert the lion’s share of resources to fast growth, not only is host security left to hold bake sales, but immune defenses may be actively undermined.

The industry has tried to shore up the imposed deficiencies with feed restriction programs, improved sanitation, and chemoprophylactic treatments.1901 USDA researchers note in a 2005 Poultry Science article: “Much of the progress seen in intensive poultry production over the past 50 yr has been possible due to the availability of very effective and inexpensive antibiotics which have prevented stress-induced opportunistic bacterial disease and allowed efficient production even as density and growth rate increased.” The researchers go on to show displeasure that human health concerns are pressuring the industry away from such crutches.1902

Despite drugs and new vaccines, the head of the prestigious Wageningen University Animal Production Systems group reached the sobering conclusion long ago that a modern broiler chicken “still cannot cope adequately with its pathogenic environment.”1903 There is only so far we may be able to subordinate chicken biology to the dictates of industrial production before running into unintended consequences.1904 “We are severely changing the way these animals grow,” remarked one poultry geneticist in “High Yielding Broiler Production: The Big Trade-Off,” an article in Broiler Industry. “I believe the time is rapidly approaching when management alone won’t be able to overcome the genetic problems because of the metabolic stresses that are being put on these birds.”1905 Or, as Rachel Carson put it 40 years ago, “Nature fights back.”1906

The history of industrial agriculture in general is replete with technological fixes associated with unforeseen consequences, such as DDT. An academic history of the broiler industry views intensive poultry production as paradigmatic in this regard. The author writes:
…virtually every effort to further industrialize broiler biology has resulted in the emergence of new risks and vulnerabilities. Intensive confinement combined with increased genetic uniformity has created new opportunities for the spread of pathogens. Increased breast-meat yield has come at the expense of increased immunodeficiency. And, of course, widespread recourse to antibiotics has created a niche for the proliferation of resistant bacteria.1907
In an industry whose bottom line is the bottom line, though, it all makes good business sense.

The poultry industry accepts the fact that broilers with the fastest growth rates start suffering from heart failure as they reach slaughter-weight and may just keel over dead, even after they have “already consumed almost all of their feed allowance and therefore taking the largest possible slice out of the profit.”1908 But not only is that readily factored into the equation, it may be welcomed as a sign of good breeding. As one chicken farmer wrote, “Aside from the stupendous rate of growth…the sign of a good meat flock is the number of birds dying from heart attacks.”1909

An interesting proviso is added by leading poultry breeding expert Gerard Albers. Although “decisions in the poultry industry are largely and increasingly driven by economic considerations,” Albers notes, “the psychological impact of flock morbidity and mortality on the farmer cannot be ignored. Mortality rates above a certain psychological threshold are unacceptable.” The excess mortality may just become too disturbing. Albers is not optimistic, though, that breeding for “increased livability” will take precedence over selection for “more profitable” traits.1910

The same attitude pervades the egg industry. In an article titled, “Industrial Perspective on Problems and Issues Associated with Poultry Breeding,” laying hen breeding corporations insist that “[e]gg production per hen housed will continue to be the single most important trait under selection.”1911

In the broiler chicken industry, the costs of production diseases are estimated at 10% to 20% of total production costs,1912 a small price to pay for jumbo-sized birds. It is simply not in the financial interest of the industry to fully mitigate disease rates. As poultry researchers have asked, “Is it more profitable to grow the biggest bird and have increased mortality due to heart attacks, ascites [heart failure], and leg problems, or should birds be grown slower so that birds are smaller, but have fewer heart, lung, and skeletal problems?” Their answer: “A large portion of growers’ pay is based on the pound of saleable meat produced, so simple calculations suggest that it is better to get the weight and ignore the mortality.”1913 In the face of bird flu viruses like H5N1, though, the deaths of chickens aren’t the only mortalities the industry may be ignoring.

The industry could breed for improved immunity even though it has “been shown to result in decreased body weight,”1914 but openly admits that “disease resistance will not be selected for if the cost in a loss of genetic improvements in other traits is too great.” The industry prefers to externalize, or pass along, disease costs to the human population. “For example,” an industry breeding text reads, “to select for effective resistance to Salmonella would currently cost so much in performance that it would be totally unfeasible.”1915 It doesn’t seem to matter that Salmonella rates in poultry continue to rise in the United States,1916 nor that hundreds of Americans die from Salmonella every year.1917 Let the consumers sterilize their meat thermometers and be extra careful not to drip a drop of fecal fluid on their kitchen floor so as not to endanger their toddlers.

Europe is reconsidering its breeding program. The European Commission’s Scientific Committee broiler chcken report stated that its “most important recommendation” was that “[b]reeders should give a considerably higher priority to health variables in the breeding index, if necessary at the expense of the selection pressure for growth and feed conversion.”1918 Meanwhile in the United States, growth rates continue to be pushed faster every year.1919