Wednesday, August 6, 2008
Saturday, July 26, 2008
During routine use, material build up and contamination of a water system can and will occur. As lime and scale deposits, rust, dirt and algae collect in the water lines, the functioning of the system will be affected. The build up of these substances, on the inner surface of the system can and will provide a place for microorganisms to take hold. The organic material can supply nutrients for growth and multiplication of microbes such as E.coli. Every time the bird consumes water it will be exposed to an increased microbial load through the drinking water which could result in poor feed conversions, down grading of carcasses, increased mortality and possibly increased condemnation.
The build up of this organic material could also have a negative effect on medication and vaccines delivered through the drinking water. To keep the watering system in proper working order, a routine monitoring, cleaning and sanitizing program should be developed and applied.
The environmental protection agency of the U.S.D.A allows 5,000 coliforms per 100 ml of potable water. However, resources from major poultry officials consider any number to be unacceptable. (Good 1985, Lacy 1994, Koelkbeck 1989).
The following information is to inform the reader of the choices available for water line sanitation and disinfection. One must continue to strive for water quality, as this ingredient is a key component towards poultry health.
Cleaning and sanitizing of water lines
I) Cleaning between flocks (shocking the line)
Probably the most critical time period for the cleaning of a water line system. Cleaning water lines should be a part of the routine barn cleaning and disinfection program.
1)Flush the lines with high-pressure water to dislodge heavy organic matter.
2)Fill the lines with the cleaning solution and leave it in the lines for 3 to 6 hours.
3)Clean the proportioner and change filters.
4)Flush the water lines with clean water.
5)All plasons, cups and other open drinkers must be cleaned as well.
* Do not use these concentrations when birds are in the barn
II) Cleaning With Birds Present
The objective is to keep the water lines clean while birds are in the house. This helps to remove and prevent organic build up in the water lines:
1)Medicate or dilute the indicated concentrations to provide the level needed for cleaning (Table 2).
2)Cleaning should be stopped 2 days prior to vaccination and water medication.
3)When starting this program, monitor the birds behavior to make sure they are drinking water.
III) Sanitizing Water Lines
The objective of water sanitizing is to decrease the number of microorganisms (bacteria and viruses) in the water lines. The addition of a sanitizer to the watering system not only helps to reduce the microbial load but also aids in minimizing the algae growth, mineral deposits and slime build up. The addition of chlorine also helps to reduce oxidation of iron, which helps control rust deposits in the water lines. Keep in mind that a sanitizer should not be used 48 hours prior to and 24 hours after vaccination.
Points to consider when cleaning and sanitizing water lines
1) Some cleaners in combination with medications can enhance delivery and activity.
i) Ammonia, at low levels helps to increase the solubility of sulfa drugs.
ii) Citric acid helps keep tetracycline in solution.
iii) Citric acid as a carrier for vitamins and minerals, rather than sugar, helps reduce slime build up.
2) Some products and combinations warrant some caution.
i) Hydrogen peroxide at full concentrations can be corrosive and tissue damaging.
ii) Iodine is corrosive to galvanized steel, rubber and latex.
iii) Citric acid is corrosive to galvanized steel.
iv) Chlorine at high levels can be corrosive to all metals including stainless steel.
v) Chlorine, ammonia and commercial cleaning agents should not be mixed together since some combinations can react producing dangerous gases.
Since poultry consume about twice as much water as they do feed, it is logical that water quality and content should be considered as one of the most important nutritional elements in production. Therefore, following a water quality assurance program based on monitoring, cleaning and sanitizing should be the most important protocol to implement. With these measures in place, there is no doubt that production parameters will be maintained and optimized.
Canadian Poultry Consultants Ltd.
Sunday, July 20, 2008
HOW DO VACCINATIONS PROTECT YOUR BIRDS?
All chicks are vaccinated at the hatchery, and some chicks receive "booster" vaccinations after they have been in the grow-out house for several days. Have you ever wondered, "How do these vaccinations protect my chicks?"
The purpose of all vaccinations is to cause the birds to develop immunity to pathogens. Pathogens are things like bacteria and/or viruses. Marek's, Newcastle, Infectious Bronchitis, and Gumboro are diseases caused by viral pathogens that we normally vaccinate chicks against.
Vaccines against viruses consist of attenuated viruses that are either in cells or freed from cells. Attenuation means to reduce the ability of the virus to cause disease, that is, decrease its virulence. This is done by putting the virus through several replication cycles in embryonic cells. Then the virus is either freed from the embryonic cells or the vaccine is prepared using viruses still in the cells.
For purposes of illustration, we will assume that our chicks are vaccinated with a Marek's disease vaccine. Within minutes after the vaccine enters the body of the chick, it will be "eaten" by phagocytes. These are large cells that occur everywhere in the body. Their function is to remove foreign materials from the body. After the phagocyte has removed the Marek's virus that was in the vaccine, it will then pass a message to certain lymphocytes (white blood cells), it has encountered a foreign pathogen. The lymphocytes that receive the message originated either in the bursa of Fabricius (bursa) or in the thymus.
The bursa is a small gland located in the tail region of the bird. It looks like a flesh-colored fig. The bursa provides an environment in which certain lymphocytes, called B-cells, develop that can produce antibodies. The thymus has a series of six to seven lobes of tissue located on each side of the throat adjacent to the esophagus. Like the bursa, it provides an environment for maturation of lymphocytes, called T-cells, that produce chemicals called cytokines. These are protein-like molecules that have many functions. For instance, they kill unwanted cells that may enter the body, reject foreign tissues, kill viruses, or kill malignant cells.
The message passed from the phagocyte to the appropriate B- and T-cells will be, "B-cells make antibodies, and T-cells make cytokines against Marek's disease virus!" The next question is, "How does the phagocyte know how to do this?" This is still a mystery of science.
As soon as the B- and T-cells receive the "go" message from the phagocyte, they enter the spleen and attach to "nurse" cells. The B- and T-cells, under the constant care of the nurse cells, swell and soon divide each into two daughter cells. The two daughter cells will divide, and their daughters will divide, and so on. It takes only about 9 minutes for a division to occur. So, in a short time, we have two clones of B-cells formed as well as two clones of T-cells. The first clone of cells is called primary responders, and the second clone of cells is called memory cells.
The first clone of B-cells immediately start producing antibodies against Marek's disease virus and the first clone of T-cells produce cytokines against Marek's virus. The second clone of both B- and T-cells simply continue to divide. These memory cells do not respond during primary responses.
Figure 1 shows antibody levels in the blood that are a direct result of the action of the first clone.
NOTE SEVERAL THINGS ABOUT THESE ANTIBODY LEVELS:
• No antibodies are present until about 2 days after vaccination.
• Peak antibody level occurs at about Day 8.
• The peak lasts only a short time, and antibody levels then begin to decrease.
• By Day 14, all the antibody in the blood is gone. This is a typical primary humoral immune response. The T-cells react like the B-cells and produce what is termed a primary cell-mediated immune response.
"Would primary humoral and cell-mediated immune responses to a viral pathogen such as Marek's protect the chicks?" The answer is "No." If this were all of the protection the body can give, the chicks would have the disease.
Let's assume that when the vaccinated chicks are 14 days old, an unwanted rat enters the house and leaves behind feces loaded with live and highly virulent Marek's disease virus. Within 12 hours, the virus challenges every chicken in the house. The second clone of daughter cells (both B- and T-cells), called memory cells that did not respond during the primary responses, now responds dramatically.
We do not know what the signals for memory responses are, but the reaction, as shown in Figure 2, is immediate production of large amounts of antibody and cytokines. These memory responses destroy the invading Marek's virus and prevent the chicks from becoming ill. This is termed a secondary or memory immune response.
THESE ARE CHARACTERISTICS OF THIS RESPONSE:
• Rapid production and release of antibodies into the bloodstream so that by 2 days after challenge, antibody levels peak.
• Peak antibody levels are normally at least twice as high as levels during the primary response.
• Antibody levels remain high indefinitely. Cytokine production during a memory response has the same characteristics as a secondary response. Cytokine levels rise to high levels very quickly and remain elevated until the virus is cleared from the body.
"Will these memory responses protect the birds against Marek's disease?" The answer is a definite "YES!" This is immunity, and it is correctly defined as the ability to remember a pathogenic challenge and then to respond in a protective way whenever this pathogen is encountered again.
All classes of poultry are susceptible to mites, some of which are blood-suckers, while others burrow into the skin or live on or in the feathers. Others occur in the air passages and in the lungs, liver and other internal organs. Poultry mites cause retarded growth, reduced egg production, lowered vitality, damaged plumage and even death. Much of the injury, consisting of constant irritation and loss of blood, is not apparent without careful examination.
Of primary concern to the poultryman is the Northern Fowl Mite (Ornithonyssus sylviarum) which is a frequent and serious pest of chickens. Heavy infestations result in low condition of the birds and lower egg production, as well as a scabby skin condition. The mite remains on the bird and does more damage than any other species of mite. The mite does not leave the host bird, as do may species of mites, and can be observed on birds in large numbers during daylight hours. It prefers the feathers below the vent and around the tail, but can be found on all parts of the body. The mite is extremely small and a microscope or magnifying glass may be needed to see it.
The female northern fowl mite lays eggs on feathers where the young mites complete their development without leaving the host. Since they remain on the fowl most of the time, treatment of the birds is necessary to destroy the mites.
The Common Chicken Mite (Dermanyssus gallinae) is the most common mite found on all types of poultry. It is a blood-sucker, and when present in large numbers, loss of blood and irritation may be sufficient to cause anemia. Egg production is seriously reduced.
This mite feeds at night, and usually remains hidden in cracks and crevices during the day. It attacks birds at night while they are on the roost. In heavy infestations, some mites may remain on the birds during the day. About a day after feeding, the female lays eggs in cracks and crevices of the house. The eggs hatch and the mites develop into adults within about a week. During cold weather, the cycle is slower. A poultry house remains infested four to five months after birds are removed.
Since the mite feeds on wild birds, these birds may be responsible for spreading infestations. However, it is more likely that spread of the mite is promoted by using contaminated coops. Human carriers are also important. Since these mites do not stay on the birds during the day, apply treatments to houses and equipment as well as the birds.
The Scaly-Leg Mite (Knemidocoptes mutans) lives under the scales on feet and legs of poultry. It also may attach to the comb and wattles. It causes a thickening of scales on the feet and legs that gives the impression that the scales are protruding directly outward, rather that laying flat on the limb. It spends its entire life cycle on the birds and spreads mainly by direct contact.
The Depluming Mite (Knemidocoptes laevis, variety gallinae) causes severe irritation by burrowing into the skin near the bases of feathers and frequently causes feathers to be pulled out or broken. The mite is barely visible to the naked eye and can be found in follicles at the base of the feathers. The mites crawl around the birds at times, spreading from bird to bird.
The most effective treatment for all mite species is a regular inspection and spraying program of both the birds and their premises. An appropriate solution of permethrin, when sprayed on the birds, will eliminate all mites that infest the bird. The spraying of all facilities will ensure that any mites hiding in cracks and crevices will be destroyed. The treatment should be repeated on a one to two month schedule or whenever populations of the mites are detected.
The primary effects of lice on their hosts are the irritations they cause. The birds become restless and do not feed or sleep well. They may injure themselves or damage their feathers by pecking or scratching areas irritated by lice. Body weight and egg production may drop.
All lice infecting poultry and birds are the chewing type. Mites may be confused with lice, but mites suck blood. In general, each species of lice is confined to a particular kind of poultry, although some may pass from one kind to another when birds are closely associated. Chickens usually are infested with one or more of seven different species; turkeys have three common species.
All species of poultry lice have certain common habits. All live continuously on feathered hosts and soon die if removed. The eggs are attached to the feathers. Young lice resemble adults except in color and size. Lice differ in preferred locations on the host, and these preferences have given rise to the common names applied to various species.
In general, the incubation period of lice eggs is four to seven days, and development of the lice between hatching and the adult stage requires about twenty-one days. Mating takes place on the fowl, and egg laying begins two to three days after lice mature. The number of eggs probably ranges from fifty to three-hundred per female louse.
As the name suggests, the Head Louse (Cuclotogaster heterographa) is found mainly on the head, although it occurs occasionally on the neck and elsewhere. It usually is located near the skin in the down or at the base of the feathers on the top and back of the head and beneath the beak. In fact, the head of the louse often is found so close to the skin that poultrymen may think it is attached to the skin or is sucking blood. Although it does not suck blood, the head louse is very irritating and ranks first among lice as a pest of young chickens and turkeys. Heavily infested chicks soon become droopy and weak and may die before they are a month old. When the chickens become fairly well feathered, head lice decrease but may increase again when the fowls reach maturity.
This louse is oblong, grayish and about 1/10-inch long. The pearly-white eggs are attached singly to the down or at the base of the small feathers on the head. They hatch within five days into minute, pale, translucent lice resembling adults in shape.
The Body Louse (Menacanthus stramineus) of chickens prefers to stay on the skin rather than on the feathers. It chooses parts of the body that are not densely feathered, such as the area below the vent. In heavy infestations, it may be found on the breast, under the wings and on other parts of the body, including the head.
When the feathers are parted, straw-colored body lice may be seen running rapidly on the skin in search of cover. Eggs are deposited in clusters near the base of small feathers, particularly below the vent, or in young fowls, frequently on the head or throat. Eggs hatch in about a week and lice reach maturity within twenty days.
This is the most common louse infesting grown chickens. When present in large numbers, the skin is irritated greatly and scabs may result, especially below the vent.
The Shaft Louse or small body louse (Menopon gallinae) is similar in appearance to the body louse, but smaller. It has a habit of resting on the body feather shafts of chickens where it may be seen running rapidly toward the body when feathers are parted suddenly. Sometimes as many as a dozen lice may be seen scurrying down a feather shaft.
Since the shaft louse apparently feeds on parts of the feathers, it is found in limited numbers on turkeys, guinea fowl and ducks kept in close association with chickens. It does not infest young birds until they become well feathered.
The same control measures used to eliminate mite populations is effective for treating lice. It is more important to apply the insecticides directly to the bird's body rather than the premises.
Fowl Tick (Blue Bug)
The Fowl Tick (Argas persicus) may be a serious parasite of poultry if it becomes numerous in poultry houses or on poultry ranges. The tick is a blood-sucker, and when present in large numbers it results in weakened birds, reduced egg production, emaciation and even death. The fowl tick is found throughout most of the South and is extremely hardy. Ticks have been kept alive without food for more than three years. The ticks will feed on all fowl.
Fowl ticks spend most of their lives in cracks and hiding places, emerging at night to take a blood meal. Mating takes place in the hiding areas. A few days after feeding, the female lays a batch of eggs. In warm weather the eggs hatch within fourteen days. In cold weather they may take up to three months to hatch. Larvae that hatch from the eggs crawl around until they find a host fowl. They remain attached to the birds for three to ten days. After leaving the birds they find hiding places and molt before seeking another blood meal. This is followed by additional moltings and blood meals.
Ticks are difficult to eradicate and methods employed must be performed carefully. It is not necessary to treat the birds, but houses and surrounding areas must be treated thoroughly.
Chiggers, Red Bugs or Harvest Mites
These pests (Trombicula splendens, Trombicula alfreddugesi, and Neoschongastia americana americana) attack chickens and turkeys, as well as humans. Normally these small mites feed on wild animals, birds, snakes and lizards. Only the larvae of chiggers attack poultry or animals; adult mites feed on plants.
Larvae usually attach to the wings, breasts and necks of poultry. They inject a poisonous substance that sets up local irritation and itching. After a few days, the larvae become engorged and drop off. Injury to grown fowl may not be apparent or noticed until the bird is dressed; then the lesions are readily apparent and greatly reduce the carcass value. Young chickens or turkeys may become droopy, refuse to eat and die. Due to methods of raising poultry, turkeys are more affected than chickens.
Control of External Parasites
There are many insecticides available to help control external poultry parasites. The most effective broad spectrum insecticide is permethrin. Permethrin has a significant residual activity, thus making it ideal for treating facilities and equipment. At reduced concentrations it can be applied to the bird. Follow all manufacturers recommendations when using all insecticides.
Ascarids (Large Intestinal Roundworms)
One of the most common parasitic roundworms of poultry (Ascaridia galli) occurs in chickens and turkeys. Adult worms are about one and a half to three inches long and about the size of an ordinary pencil lead. Thus, they can be seen easily with the naked eye. Heavily infected birds may show droopiness, emaciation and diarrhea. The primary damage is reduced efficiency of feed utilization, but death has been observed in severe infections.
Chickens of three to four months of age show resistance to infection. Specimens of this parasite are found occasionally in eggs. The worm apparently wanders from the intestine up the oviduct and is included in the egg contents as the egg in being formed.
The life history of this parasite is simple and direct. Females lay thick heavy-shelled eggs in the intestine that pass in the feces. A small embryo develops in the egg but does not hatch immediately. The larvae in the egg reaches infective stage within two to three weeks. Embryonated eggs are very hardy and under laboratory conditions may live for two years. Under ordinary conditions, however, few probably live more than one year. Disinfectants and other cleaning agents do not kill eggs under farm conditions. Birds become infected by eating eggs that have reached the infective stage.
Available drugs remove only the adult parasite. The immature form probably produces the most severe damage. The treatment of choice is piperazine. Many forms of piperazine are produced, and all are effective if administered properly. Piperazine is only effective for treating this parasite. It has no effect on other internal parasites of fowl. Follow the manufacturer's instructions carefully.
The parasite can be controlled by strict sanitation. If the birds are confined, clean the house thoroughly and completely before a new group is brought in. Segregate birds by age groups, with particular care applied to sanitation of young birds. If birds are on range, use a clean range for each group of birds.
This parasite (Heterakis gallinae) is found in the ceca of chickens, turkeys and other birds. The worms are small, white and measure _ to ½ inch in length.
This parasite apparently does not seriously affect the health of the bird. At least no marked symptoms or pathology can be blamed on its presence. Its main importance is that it has been incriminated as a vector of Histomonas meleagridis, the agent that causes blackhead. This protozoan parasite apparently is carried in the cecal worm egg and is transmitted from bird to bird through this egg.
The life history of this parasite is similar to that of the common roundworm. The eggs are produced in the ceca and pass in the feces. They reach the infective form in about two weeks. In cool weather, this may take longer. The eggs are very resistant to environmental conditions and will remain viable for long periods.
The cecal worm can be effectively treated with fenbendazole. Since the worm itself produces no observable damage and the eggs live for long periods, it is advisable and necessary to keep chickens and turkeys separated to prevent spread of blackhead.
Capillaria (Capillary or Thread Worms)
There are several species of Capillaria that occur in poultry. Capillaria annulata and Capillaria contorta occur in the crop and esophagus. These may cause thickening and inflammation of the mucosa, and occasionally severe losses are sustained in turkeys and game birds.
In the lower intestinal tract there may be several different species but usually Capillaria obsignata is the most prevalent. The life cycle of this parasite is direct. The adult worms may be embedded in the lining of the intestine. The eggs are laid and passed in the droppings. Following embryonation that takes six to eight days, the eggs are infective to any other poultry that may eat them. The most severe damage occurs within two weeks of infection. The parasites frequently produce severe inflammation and sometimes cause hemorrhage. Erosion of the intestinal lining may be extensive and result in death. These parasites may become a severe problem in deep litter houses. Reduced growth, egg production and fertility may result from heavy infections.
If present in large numbers, these parasites are usually easy to find at necropsy. Eggs may be difficult to find in droppings, due to the small size and time of infection.
Since treatment for capillaria is often lacking, control is best achieved by preventive measures. Some drugs, fed at low levels, may be of value in reducing the level of infection on problem farms. Game birds should be raised on wire to remove the threat of infection. As some species of capillaria have an indirect life cycle, control measures may have to be directed toward the intermediate host. Hygromycin and meldane may be used for control. Additional vitamin A may be of value. Effective treatments that are not approved by the Food and Drug Administration are fenbendazole and leviamisole.
Tapeworms or cestodes are flattened, ribbon-shaped worms composed of numerous segments or division. Tapeworms vary in size from very small to several inches in length. The head or anterior end is much smaller than the rest of the body. Since tapeworms may be very small, careful examination often is necessary to find them. A portion of the intestine may be opened and placed in water to assist in finding the tapeworms.
The pathology or damage tapeworms produce in poultry is controversial. In young birds, heavy infections result in reduced efficiency and slower growth. Young birds are more severely affected than older birds.
All poultry tapeworms apparently spend part of their lives in intermediate hosts, and birds become infected by eating the intermediate hosts. These hosts include snails, slugs, beetles, ants, grasshoppers, earthworms, houseflies and others. The intermediate host becomes infected by eating the eggs of tapeworms that are passed in the bird feces.
Although several drugs are used to remove tapeworms from poultry, most are of doubtful efficacy. In general, tapeworms are most readily controlled by preventing the birds from eating the infected intermediate host. Tapeworm infections can be controlled by regular treatment of the bird with fenbendazole or leviamisole.
The gapeworm (Syngamus trachea) is a round red worm that attach to the trachea (windpipe) of birds and causes the disease referred to as "gapes". The term describes the open-mouth breathing characteristic of gapeworm-infected birds. Heavily infected birds usually emit a grunting sound because of the difficulty in breathing and many die from suffocation. The worms can easily block the trachea, so they are particularly harmful to young birds.
The gapeworm is sometimes designated as the "red-worm"; or "forked-worm" because of its red color and because the male and female are joined in permanent copulation. They appear like the letter Y. The female is the larger of the two and is one-fourth to one inch in length. The male gapeworm may attain a length of one-fourth inch. Both sexes attach to the lining of the trachea with their mouthparts. Sufficient numbers may accumulate in the trachea to hinder air passage.
The life cycle of the gapeworm is similar to that of the cecal worm; the parasite can be transmitted when birds eat embryonated worm eggs or earthworms containing the gapeworm larvae. The female worm lays eggs in the trachea, the eggs are coughed up, swallowed, and pass out in the droppings. Within eight to fourteen days the eggs embryonate and are infective when eaten by birds or earthworms. The earthworm, snails and slugs serve as primary intermediate hosts for the gapeworm. Gapeworms in infected earthworms remain viable for four and a half years while those in snails and slugs remain infective for one year. After being consumed by the bird, gapeworm larvae hatch in the intestine and migrate from the intestine to the trachea and lungs.
Gapeworms infect chickens, turkeys, guinea fowl, pheasants, chukar partridge, and probably other birds. Young birds reared on soil of infected range pens are at high risk (pen-raised game birds). Some control or reduction in infection density (worms/bird) is achieved by alternating the use of range pens every other year and/or using a pen for only one brood each year. Tilling the soil in the pens at the end of the growing season helps to reduce the residual infection. Treating the soil to eliminate earthworms, snails and slugs is possible but the cost is usually prohibitive.
Gapeworms are best prevented by administering a wormer at fifteen to thirty day intervals or including a drug at low levels continuously beginning fifteen days after birds are placed in the infected pens. One drug that is effective for eliminating gapeworms is fenbendazole, however, its use is not presently approved for use in birds by the Food and Drug Administration.