Immunity and the Gamecock
by John Purdy
A healthy gamecock is a wonderful sight: brilliant feathers, bright eyes, red head, always moving and talking, challenging the world to a fight. The only way a gamecock can reach his genetic potential is through good management, including preventing and controlling disease.
The ability of the immune system to defend the body against disease organisms depends on several factors, many of which can be controlled by correct management of the flock. The following article outlines the basic components of the avian immune system, their role in preventing disease, and techniques that are available to prevent disease and enhance the immune response.
The avian immune system is actually composed of two different and complex immune mechanisms that work together to keep birds healthy and resistant to disease. The innate or non-specific arm of the immune system is the first line of defense. Examples of this system include genetic resistance, body temperature, and the presence of normal or beneficial bacteria which physically and chemically prevent the growth of harmful bacteria. Other examples of innate immunity are the body’s physical barriers to invasion such as the skin, the mucous membranes that line the respiratory and digestive tracts, and the respiratory cilia (fine hair-like structures), which trap and “sweep” dust, bacteria and other debris out of the trachea (wind pipe). Another component of innate immunity is the “complement” system (proteins and enzymes which circulate in the blood and attach to invaders and kill them). The last component of innate immunity are large scavenging cells called macrophages. These important cells travel throughout the body, engulfing and destroying foreign bacteria, virus particles, fungi, and other debris, and aid in the further development of the immune response, as explained in the next paragraph.
The second arm of the avian immune system is called acquired or specific immunity. This system is activated when the first line of defense (innate system) is overcome by disease challenge. B-lymphocytes or “B-cells” are a type of white blood cell and are activated when the macrophage engulfs the invading disease organism. The B-cell communicates with the surface of the macrophage, and if a foreign invader is detected, the B-cells first begin to reproduce themselves and then begin producing specific antibodies, otherwise known as immunoglobulins. Antibody production begins after 4 to 5 days, and peaks at 3-4 weeks. Antibodies circulate in the blood, and many perform their role by attaching to the surface of disease organisms, preventing the harmful bacteria or virus from attaching to the target cells in the chicken. Other antibodies enhance the efficiency of the complement and macrophage activity against disease organisms. Once exposed to a specific disease organism, the B-cells display a “memory” of that organism, and can respond to future challenges much more rapidly. The B-lymphocyte/antibody immune response is responsible for the protection afforded by vaccinations, in which a weakened or killed bacteria or virus is introduced into the body, allowing the “memory” capabilities of the B-cells to be activated and readied to produce antibodies if the B-cells detect the disease challenge in the future.
The B-lymphocyte/antibody immune response primarily prevents the disease organism from entering and damaging the target cells of the chicken. However, if the immune response was not able to prevent this from occurring, the next response by the acquired immune system is the production of T-lymphocytes. Depending on the specific type of T-cell, these cells can attack the organism directly, enhance the function of other cells involved in immune function (e.g., B-cells and macrophages), and kill infected cells when required.
When a chicken is exposed to a disease organism and produces antibodies itself, this is called ”active immunity”. When a chick is hatched, the hen provides antibodies through the egg. Mammals secrete antibody-rich colostrum through the milk to their newborns. Obtaining pre-made antibodies is termed ”passive immunity”. New feed additives are available which furnish egg-derived antibodies to livestock and poultry, and have been demonstrated to provide protection against many disease organisms. In fact, hens are such efficient antibody factories that egg-derived antibodies are becoming the mainstay for research and innovative immune therapy in humans. Certain vaccination programs for poultry are timed so that they are administered after the maternal antibodies have diminished somewhat, so that the chick’s B-cell’s are stimulated into producing antibodies and active immunity to the pathogen. If the vaccination is administered after the maternal antibodies have severely diminished, a reaction to the vaccination is possible.
Prevention of disease requires effective management of the flock. As gamefowl breeders, our challenges are similar, yet different and can be significantly more difficult than the large-scale commercial poultry operations. Many of the standard recommendations for commercial flocks just don’t apply very well to the real life situation of the typical gamefowl breeder.
The most effective method to prevent the occurrence of disease is biosecurity: preventing contact with potential disease sources or vectors (fowl, other wild and domesticated birds, animals, people, contaminated feed, and equipment). How feasible is this to the typical gamefowl breeder? Nearly impossible! However, there are some practical tips you can implement that will reduce your chances of exposing your fowl to unnecessary disease challenge, and reducing the impact of disease should it occur.
1. Keep your young fowl separate from the adults if possible. Fowl running loose in the tie-cord area or drinking from the same water containers as the broodfowl can spread disease from one sick bird to all the rest. If young fowl are exposed to a significant disease challenge before sufficient antibodies are produced, disease may result. Many older birds may be carriers of disease, even though they do not show symptoms.
2. Before you buy fowl, determine what procedures (medications, feed additives, vaccinations, management techniques) the breeder employs to keep his fowl healthy. Find out what disease problems he has had in the past and what he did to control or eradicate them. If he uses many medications and has trouble with disease in his flock, reconsider the purchase. You are buying his fowl and his disease problem. If at all possible, examine the fowl in detail before you buy them! Slow down and truly observe the fowl – not just the flashy battlecocks, but the broodfowl and young chicks. Are they vigorous and alert, with clear eyes, brightly colored plumage and bright red heads? When they crow, are their voices clear and loud? Are young fowl and hens running all over the tie-cord area?
3. When you bring your new fowl home, keep them separate from your original birds for at least two weeks if possible. Feed, water, and handle your fowl first and the new fowl last, to prevent carrying a new disease to your fowl. Worm and de-louse them, and watch them carefully. Sometimes the stress of moving fowl to a new place and changing the feed will cause disease symptoms.
4. Select your broodfowl from the strongest, most vigorous fowl you have to choose from. Breeding from an unhealthy individual of a valuable bloodline just doesn’t work well; it’s better to lose the bloodline than take the chance of breeding genetic susceptibility to disease into your flock.
5. Explain to visitors your policy of limiting traffic on your yard to only what is necessary. If you sell chickens, consider asking your visitors to use disposable plastic booties and to wash up before they enter your yard. Disease can be easily tracked from one yard to another on boots and clothes. If you know someone who has a disease problem with his chickens, don’t let him wander around and handle your birds.
6. Eradicate rodents! Mice and rats can carry disease, including Cholera. Rodent droppings in the feed can pass these germs on to your chickens. Keep mice and rat poison available where fowl can’t reach, and make sure it’s available at all times. Use clean feed from reputable, well-managed feed mills. If you see piles of wasted feed, evidence of rodent infestation and other unsanitary practices, start looking for another source of feed.
7. I recommend feeding twice a day for several reasons, but one reason is that if you feed only once per day, often your fowl will leave a little feed for later in the day or the next morning, if you feed in the evening. The left-over feed will attract wild birds and mice, which may carry disease. For large operations this may not be possible, but for the majority of breeders, twice a day feeding pays off.
8. If you have the space, move your fowl on fresh ground frequently. A model gamefowl facility would have a duplicate yard area for tie cords, range for young fowl, and portable brood pens. Periodically, the entire operation should be moved to fresh ground, allowing the ground to rest and reducing the exposure of the fowl to the buildup of droppings. Some partnerships involve individuals with different farms that specialize in the different aspects of producing gamefowl for battle: breeding, raising the young fowl, and conditioning. This is an ideal set up to prevent the transmission of disease from one age of birds to another, although keep in mind that people and equipment moving between farm can spread diseases, too.
9. When setting up your yard and broodpens, a gentle slope is better than flat, low-lying ground because it will drain better. Low-lying ground invites breeding mosquitos (Fowl Pox) and allows waste from droppings to build up.
10. Worm and delouse your fowl on a regular basis. These parasites can rob your fowl of valuable energy and make them susceptible to disease.
11. Implement a vaccination program for common poultry diseases in your area, and any hard to control diseases particular to your flock. Marek’s and Newcastle are two diseases that can be prevented through vaccination. In some areas, Fowl Pox and Coryza are consistent problems, and should be included in a vaccination program. There are many other diseases for which vaccines are availabe. Be sure you carefully follow directions or you can get a severe reaction from the vaccine. Try vaccinating at night to reduce stress.
12. Perhaps one of the most important aspects of disease control is carefully observing your fowl for any changes in their appetite, changes in the color and consistency of the droppings, respiratory rattles, sneezes, coughs, ruffled feathers, slow movement, and other changes from normal. These are symptoms requiring action! If possible, isolate the affected birds immediately from the rest of the flock. Administering a broad-spectrum antibiotic in the water to the entire flock while you attempt to diagnose the disease is usually a good idea. Most states have a land-grant agricultural university with an animal diagnostic laboratory that will diagnose the disease, usually for free, although you may have to work through a local veterinarian to submit the birds. Contact a local vet or an agricultural extension agent for information. Diagnostic labs will need several (2-3) affected birds (preferably alive, or very fresh dead), plus background information about the flock (number of birds affected, age of birds, what the symptoms are and when they were noticed, vaccination program used, medications used, etc.) . The diagnostic lab will furnish the disease diagnosis, and give specific treatment and prevention recommendations, usually within a week to 10 days. Don’t hesitate to call them and ask a bunch of questions. Your tax dollars pay their salary!
13. Keep your fowl healthy so that their immune system is strong and can overcome disease challenge. Provide a balanced diet, clean water, and control stress conditions (see “Nutrition, Stress and the Gamecock”). Consider using natural immune system boosters to prevent disease rather than the routine use of antibiotics which builds resistance in the disease organisms and can permanently harm the immune system. Natural products which have been proven to increase immunity include “probiotics” or direct fed microbials , which are beneficial intestinal bacteria, certain vitamins and minerals such as vitamin E and selenium, herbs such as Echinacea (purple coneflower) and Goldenseal, avian antibodies, which provide passive immunity to disease challenge, and others.
The study of the immune system is complex and is constantly evolving as new research is conducted. We can get the most out of our fowl by breeding only the healthiest ones, preventing exposure, vaccinating when necessary, rapidly and accurately diagnosing and treating disease when it occurs, and strengthening and maintaining the fowl’s natural immune system.