Poultry breeding, health, and care. @wiki 60252 2008-07-02T02:12:55Z @wiki::131/ 2008-07-02 2008-07-02T02:12:55Z

Sometimes it is necessary to test the incubated eggs for fertility. If large numbers of infertile eggs are incubated, they can be found and discarded, and the extra space used for additional eggs. This test will not injure the young embryos and is reliable for eliminating eggs that will not hatch. Make a tester or candler by placing a light bulb and fixture inside a cardboard box. Cut a small, round hole in the top or side of the box, and let a narrow beam of light escape from the box. You can see the internal features of the egg by placing it against the hole. A darkened room makes testing easier. The eggs are normally tested after 4 to 7 days of incubation. Eggs with white shells are easier to test and can be tested earlier than dark shelled eggs. Two classes of eggs can be removed on the basis of this early test, "infertiles" and "dead germs." "Infertile" refers to an unfertilized egg or an egg that started developing but died before growth could be detected. "Dead germs" refers to embryos that died after growing large enough to be seen when candled. An "infertile" appears as a clear egg except for a slight shadow cast by the yolk. A live embryo is spider-like in appearance, with the embryo representing a spider's body and the large blood vessels spreading out much like a spider's legs. A "dead germ" can be distinguished by the presence of a blood ring around the embryo. This is caused by the movement of blood away from the embryo after death. ==Sources== http://msucares.com/poultry/reproductions/poultry_testing_embryo.html

@wiki::130/ 2008-07-02 2008-07-02T02:08:07Z

The size and type of '''incubator''' selected depends on the needs and future plans of each producer. Many different models are available. For continuous settings, separate incubator and hatcher units are recommended. If all eggs in the unit are at the same stage of incubation, a single unit can be used. Locate the incubator and hatcher units indoors to protect them from major weather changes. It is essential that the room has a good ventilation system to supply plenty of fresh air. Keeping the units indoors makes it easier to maintain uniform temperature and humidity. There are basically two types of incubators available, forced-air and still-air incubators. Forced-air incubators have fans that provide internal air circulation. The capacity of these units may be very large. The still-air incubators are usually small without fans for air circulation. Air exchange is attained by the rise and escape of warm, stale air and the entry of cooler fresh air near the base of the incubator. Recommended temperatures vary between the two incubators, so follow the manufacturer's recommendation that accompany the units. ==Sources== http://www.msstate.edu/dept/poultry/hatch.htm#sel

@wiki::129/ 2008-07-02 2008-07-02T02:06:47Z

Many times a producer carefully attends to the incubation process but disregards the care of the eggs before they are placed in the incubator. Even before incubation starts the embryo is developing and needs proper care. Hatching eggs suffer from reduced hatchability if the eggs are not cared for properly. Listed below are tips to help maintain hatching egg quality. 1. Collect eggs at least three times daily. When daily high temperatures exceed 85 degrees F. increase egg collection to five times daily. Collect two or three times in the morning and one or two times in the afternoon. 2. Slightly soiled eggs can be used for hatching purposes without causing hatching problems, but dirty eggs should not be saved. Do not wash dirty eggs. 3. Store eggs in a cool-humid storage area. Ideal storage conditions include a 55 degree F. temperature and 75% relative humidity. Store the eggs with the small end pointed downward. 4. Alter egg position periodically if not incubating within 4-6 days. Turn the eggs to a new position once daily until placing in the incubator. 5. Hatchability holds reasonably well up to seven days, but declines rapidly afterward. Therefore, do not store eggs more than 7 days before incubating. After 3 weeks of storage, hatchability drops to almost zero. Plan ahead and have a regular hatching schedule to avoid storage problems and reduced hatches. 6. Allow cool eggs to warm slowly to room temperature before placing in the incubator. Abrupt warming from 55 degrees to 100 degrees causes moisture condensation on the egg shell that leads to disease and reduced hatches. ==Sources== http://www.msstate.edu/dept/poultry/hatch.htm#sel

@wiki::128/ 2008-07-02 2008-07-02T02:04:19Z

Most producers set as many eggs as their breeders produce. If incubator space is the limiting factor, it is more profitable to select the better quality eggs for incubating. A few tips to follow when selecting '''hatching eggs''' are: * Select eggs from breeders that are (1) well developed, mature and healthy; (2) compatible with their mates and produce a high percentage of fertile eggs; (3) are not disturbed much during the mating season; (4) fed a complete breeder diet; and (5) not directly related [brother, sister, mother, father, etc.]. * Avoid excessively large or small eggs. Large eggs hatch poorly and small eggs produce small chicks. * Avoid eggs with cracked or thin shells. These eggs have difficulty retaining moisture needed for proper chick development. Penetration of disease organisms increase in cracked eggs. * Do not incubate eggs that are excessively misshapen. * Keep only clean eggs for hatching. Do not wash dirty eggs or wipe eggs clean with a damp cloth. This removes the egg's protective coating and exposes it to entry of disease organisms. The washing and rubbing action also serves to force disease organisms through the pores of the shell. ==Sources== http://www.msstate.edu/dept/poultry/hatch.htm#sel

@wiki::127/ 2008-07-02 2008-07-02T01:49:11Z

Maximum hatchability requires fresh eggs from well-bred and properly managed flocks. However, egg care and incubation is even more critical. What follows is an analysis of common problems seen during this type of project. Check on the problem for a discussion of the possible causes and how they may be corrected. '''Problem #1''': Eggs clear - no blood rings, no embryonic development Causes: * Eggs infertile. * Eggs damaged by being either badly chilled or overheated. * Eggs held too long or held under improper conditions. '''Correction:''' o Keep eggs under proper temperature and humidity conditions and set within seven (7) days after date laid. o Get eggs from another source. '''Problem #2''': Eggs candling clear but showing blood ring or very small embryo when broken-out. . Causes: * Badly chilled eggs or eggs overheated or held at too high a temperature. * Improper incubator temperature at earliest stage of incubation. * Eggs held too long or held under improper conditions of temperature and humidity. '''Correction:''' o Protect eggs against freezing temperatures, gather eggs often, cool properly and quickly; hold eggs under conditions recommended by breeder. o Check accuracy of thermometer. Operate incubator at proper temperature. o Keep eggs under proper temperature and humidity conditions and set them within seven (7) days after date laid. '''Problem #3''': Early dead embryos during one to six days into incubation. Causes: * Temperature too high or too low in incubation. * Lack of ventilation. * Improper turning of eggs. '''Correction:''' o Check accuracy of thermometer. Operate incubator at proper temperature. o Provide adequate ventilation of the incubator room and proper openings of the incubator ventilators. Do not recirculate air. Supply 100 percent fresh, tempered air. o Turn eggs at regular intervals 3 times daily. '''Problem #4''': Any considerable number of embryos dead from the sixth through the sixteenth days of incubation (normally this is a period of relatively low embryonic death). Causes: * Incubator temperature too high. * Infected embryos either by infection from hens, or especially, by external microbial contamination through shell. * Lack of ventilation. '''Correction:''' * Check accuracy of thermometer. Operate incubator at proper temperature. * Provide adequate ventilation of the incubator room and proper openings of the incubator ventilators. '''Problem #5:''' Chicks fully formed, but dead without pipping. May have considerable quantities of unabsorbed yolk. Causes: * Low average humidity in incubator. * See probable causes in problem #3 above. * Chilled eggs. '''Correction:''' * Maintain proper humidity throughout incubation cycle. * Gather eggs quickly, cool properly and hold under proper conditions. '''Problem #6:''' Eggs pipped, but chicks dead in shell. Causes: * Low average humidity. * Inadequate ventilation. * Excessive high temperature for a short period. * Low average temperature. '''Correction:''' * Maintain proper humidity levels throughout incubation cycle. * Provide adequate ventilation of the incubator room and proper openings of the incubator ventilators. * Guard against temperature surge. * Maintain proper temperature throughout incubation cycle. '''Problem #7:''' Sticky chicks - chicks smeared with egg contents. Causes: * Low average temperature * Average humidity too high. * Inadequate ventilation. '''Correction:''' o Use proper operating temperature. o Maintain proper humidity levels throughout incubation cycle. o Provide adequate ventilation of the incubator room and proper openings of the incubator ventilators '''Problem #8:''' Dry sticks - shell sticking to chicks. Causes: * Eggs dried down too much. * Low humidity at hatching time. * Improper egg turning. '''Correction:''' o Maintain proper humidity levels during egg-holding period and throughout incubation cycle. Do not over-ventilate. o Proper humidity levels throughout incubation cycle. o Turn eggs hourly or at least at regular intervals eight times daily. '''Problem #9:''' Chicks hatching too early with bloody navels. Causes: * Temperature too high. '''Correction:''' o Maintain proper temperature levels throughout incubation cycle. '''Problem #10:''' Large, soft-bodies, mushy chicks dead on trays with bad odor. Causes: * Low average temperature. * Poor ventilation in incubator. * Humidity too high during incubation. '''Correction:''' o Maintain proper temperature throughout incubation cycle. o Provide proper ventilation of the incubator room and proper opening of the incubator ventilators. o Maintain proper humidity levels throughout incubation cycle. '''Problem #11''': Short down on chicks or eyelids stuck closed with down. Causes: . o High temperature. o Low humidity. o Excessive ventilation in the incubator at hatching time. o Holding chicks in incubator too long after they hatch. '''Correction:''' * Maintain proper temperature levels throughout incubation cycle. * Maintain proper humidity levels throughout incubation cycle. * Reduce openings of incubator ventilators. Do not restrict so far as to permit animal heat to push temperature above safe level. * Remove chicks as soon as they are fluffed and ready. '''Problem #12:''' Delayed hatch - eggs not starting to pip until 21st day or later. Causes: * Average temperature too low in the incubator. * Eggs held too long. '''Correction:''' * Maintain correct temperature levels throughout incubation cycle. * Before placing them in the incubator, try not to hold eggs more than seven days and then only if holding conditions are ideal. '''Problem #13:''' Malformed chicks in poor hatch, usually associated with an excessive number of chicks dead in shell, with a high incidence of malpositions. Causes: * Eggs held too long before setting, even under good conditions, or eggs held at length of time at improper levels of temperature and/or humidity. * Eggs chilled before setting. * Improper turning or setting * Inadequate ventilation * Abnormally high or abnormally low incubator temperature. * Insufficient moisture. * Damage to eggs in shipment caused by jarring or shipping them with large end down. * Eggs from poor quality stock. '''Correction:''' * Try not to hold eggs more than seven days if at all possible and then only if holding conditions are ideal. * Gather eggs quickly, cool properly before casing, and hold under proper conditions. * Provide adequate ventilation of the incubator room and proper openings of the incubator ventilators. Do not recirculate air. Supply 100% fresh, tempered air. * Maintain proper temperature levels throughout the incubation cycle. * Maintain proper humidity levels throughout the incubation cycle. * Hatching eggs must be shipping good quality, well-protected egg cases or equivalent, with small end down. Avoid rough rough handling. ===Sources=== Embryology.com

@wiki::126/ 2008-07-02 2008-07-02T01:40:07Z

==History== The Japanese first introduced the art of sexing chickens into Queensland in 1934. Until this time, no accurate method of determining the sex of day-old chickens had been discovered. Some claimed that a ring suspended by a piece of cotton and held over a fertile egg would swing one direction for a male and the other for a female. Others claimed that egg shape indicated whether a cockerel or pullet would hatch. In 1933, Professor Masui and Professor Hashimoto published an English version of ´Sexing Baby Chickens´. In 1934, Dr Kiyoshi Oxawa visited Queensland and conducted the first classes on chicken sexing and by 1935 several Queenslanders (among them Dorothy McCulloch) had become proficient. Advantages of sexing chickens Enormous benefits have resulted from the ability to sex day-old chickens, not only to hatcheries but to the industry in general. The procedure has reduced the cost of rearing chickens by 50% which in turn has reduced labour and feed expenses. The advent of feather sexing has allowed the meat chicken industry (broilers) to separate males from females for a quicker turn around. With the sexing of any normal population, you would expect to get 50% of each sex. Methods for sexing There are four accepted methods for sexing day-old chickens: * cloacal or vent sexing (1935) * machine method (1950s) * feather sexing (1969) * colour sexing (1975). 1. Vent or cloacal sexing The art of vent or cloacal sexing of day-old chickens is difficult to master without instructions from an experienced sexer. Use the following to help develop the procedure. Before examining the vent, discharge the chicken´s excretions by lightly pressing on both sides of the abdomen in a downward motion. * Place the chicken on its back in the palm of your hand with the head towards you, put thumb and first two fingers around its thighs to hold it. * Tip your hand so that the chicken´s breast is towards you, vent uppermost. * Place your middle fingers over the chicken´s breast to support the chicken leaving your thumb free. (If you have large hands, place the chicken´s head between your little finger and ring finger for additional support.) * Place the thumb of your other hand on the lower portion of the vent (anus). * Using the index finger start from the top of the vent moving down, back and around, rolling the vent in a sideways action. * At the same time a similar action with the free thumb, starting from the top and rolling down and back. * With the thumb and forefinger placed either side of the vent apply gentle pressure and a rolling action to evert the vent and expose the male eminence or lack of it (sexed as female). After a little practice this can be accomplished without injury or significant discomfort to the chicken. The eminence or genital organ is found midway on the lower rim of the vent, and looks like a very small pimple. Even though its size and shape can vary considerably, it can be recognised with a little practice and a keen eye. Most males have a relatively prominent eminence, most females have none. However, a small proportion of both males and female have relatively small eminences. Sexing these chickens can be quite difficult but with regular practice the sexer will eventually learn to identify the differences. When learning to sex chickens it is best to assume that chickens with small eminences are female. The male eminence is solid and will not disappear upon gentle rubbing with your thumb. Having access to chickens of known sex is a great help in developing the art of vent sexing and feather sexed meat chickens are ideal for this purpose. 2. Instrument or machine sexing Instrument or machine sexing of chickens has almost disappeared, because the instruments are no longer available and spare parts cannot be obtained. The Keeler Optical (English) or Chicktester (Japanese) machine features a blunt ended telescopic tube, containing a light. The sexer inserts the tube into the evacuated cloaca and with the help of the light can identify either testis or ovaries. Successful development of this technique depends on the capability of the student and their level of experience. The steps for instrument sexing are as follows: Hold the instrument in one hand and the chicken as for vent or cloacal sexing (first three points). Thumb and first two fingers should be on either side of the chicken at thigh level. Use thumb and first two fingers to provide slight pressure near the vent to evacuate faecal contents. * Gently insert the glass tip of the machine into the chicken´s vent and down the large intestine. Extreme care is needed not to puncture the large intestine. * Use one eye to look through the instrument while keeping the other eye open. * The testicles are observed to the right of the backbone and look like a grain of rice usually a white/yellow colour, some breeds exhibit a bit of black. * If there are no testicles on the right, move the instrument to the left of the backbone and locate the ovary. This ovary is yellowish and shaped like an inverted triangle. The right ovary is diminished and unclear. 3. Feather sexing In 1969, after three years of intensive genetic research, Tegels Poultry Breeding Company developed broiler chickens which could be feather sexed. The result was a strain that would produce slow-feathering males and fast feathering females. In the slow feathering males the coverts are either the same length or longer than the primary wing feathers. In the fast feathering females, the primary wing feathers are longer than the coverts. This is caused by a gene located on the sex chromosome where slow feathering is dominant to rapid feathering and controls the rate of wing and tail feathering in the chicken. The dominant slow-feathering characteristic is passed from mothers to their sons and the rapid feathering characteristic from the fathers to their daughters. Advantages of feather sexing include: * increased rate of sexing (feather sexing is faster than machine sexing) * 99% to 100% accuracy lower labour costs (feather-sexing training requires less time than machine sexing * the skills are easily transferable. 4. Colour sexing Commercial layer breeds have been developed in which the sex of the day-old chicken is identified by plumage (colour and markings); males are predominantly white and females brown. Colour sexing as a method of sexing has had a significant impact on reducing overall costs. Conclusion As a few large companies control the chicken breeding and hatching industry around the world, greater numbers of geneticists and technicians are being employed in research and development. This has accelerated the already rapid trend to breed sex linked crosses. Consequently the skill of the chicken sexer has been superseded, virtually making the manual art of chicken sexing obsolete. ==Sources== http://www.dpi.qld.gov.au/cps/rde/dpi/hs.xsl/27_2712_ENA_HTML.htm

@wiki::125/ 2008-07-02 2008-07-02T01:56:44Z

{| class="wikitable" width="100%" | style="width:33%; vertical-align: top; background-color: #ffffff; padding:1em; border:1px solid #aaaaaa;"| ==Incubating== | style="width:33%; vertical-align: top; background-color: #ffffff; padding:1em; border:1px solid #aaaaaa;"| ==Hatching== | style="width:33%; vertical-align: top; background-color: #ffffff; padding:1em; border:1px solid #aaaaaa;"| ==Raising Chicks== *[[How to Raise Chicks]]

@wiki::124/ 2008-07-01 2008-08-04T14:22:43Z

==Poultry Mites== There are two major types of''' mites''' found on the body of poultry. They are the Northern Fowl Mite (or in tropical environ�ments, the Tropical Fowl Mite) and the Chicken Mite (or Red Roost Mite). The Northern Fowl Mite is the most common external parasite in poultry, especially in cool weather climates. It sucks blood from all different types of fowl and can live in the temperate regions of the world. As compared to the Chicken Mite, the Northern Fowl Mite primarily remains on the host for its entire life cycle. These mites can live off the host bird for 2 to 3 weeks. These mites are small and black or brown in color, have 8 legs, and are commonly spread through bird-to-bird contact. The Tropical Fowl Mite is comparable to the Northern Fowl Mite but lives in the tropical regions. The Chicken Mite is a nocturnal mite that is primarily a warm weather pest. These mites suck the blood from the birds at night �and then hide in the cracks and crevices of the houses during the day. Chicken Mites are dark brown or black, much like the Northern Fowl Mite. The life cycle of mites can be as little as 10 days, which allows for a quick turnover and heavy infestations. Mites can be transferred between flocks by crates, clothing, and wild birds. Mites are capable of living in the environment and off the host bird for a period of time. Diagnoses of mite infestations are similar to that of lice; however since mites can live off the bird and some are nocturnal, inspect birds and housing facilities at night especially if you suspect that the Chicken Mite is the cause of the infestation. Observable signs may include darkening of the feathers on white feathered birds due to mite feces; scabbing of the skin near the vent; mite eggs on the fluff feathers and along the feather shaft (Figure 2); or congregations of mites around the vent, ventral abdomen, tail, or throat. Since mites congregate around the ventral region, they can also reduce a rooster’s ability of successful matings ==Flock Symptoms== Flocks infested with lice or mites show similar general symptoms. Birds will have decreased egg production; decreased weight gain; decreased carcass-grading quality; increased disease susceptibility; and decreased food intake. If any of these generalized symptoms are observed, a visual evaluation is recommended. Inspect birds around the ventral region for signs of lice or mites since infestations usually start in this area of the bird. ==Treatments== Sanitation and cleanliness are the keys to lice and mite control. Sanitation includes cleaning and disinfecting housing facilities and equipment between flocks. Moreover, reducing people traffic through housing facilities is recommended. Eliminating the contact between flocks and wild birds can reduce the potential transfer of external parasites. Chemical control can include the use of carbaryl (Sevin®). Treat the walls, floors, roosts, nest boxes, and the birds simultaneously. When dusting an entire house, be careful to avoid feed contamination. One treatment method for small flocks or individual birds is the use of a dusting bath with Sevin®. Place the bird into a garbage bag containing the medicated powder with the birds’ head out and rotate/shake the bag to completely cover the bird with powder. Be sure not to inhale the medicated powder during treatments. The use of a facial mask is recommended to prevent inhaling this medicated powder. Because the life cycle of lice and mites is. approximately 2 weeks, treatments should be repeated every 2 weeks as needed. Carefully read all labels prior to treatment to make sure withdrawal times are followed for food-producing poultry. Severe lice or mite infestations can be treated initially with a kitten strength dose of a pyrethrin-based medicated spray on the birds to reduce the initial numbers. If problems persist, contact a veterinarian for treatment with such medications as Ivermectin�. Prevention is the best method of treatment. For poultry used in exhibition or for new poultry entering the flock, a minimum quarantine period of 2 weeks is recommended. During this time birds should be physically examined and treated if necessary. ==Sources== http://ohioline.osu.edu/vme-fact/0018.html

@wiki::123/ 2008-07-01 2008-07-01T17:50:04Z

==Caged Layer Fatigue== '''Cage layer fatigue''' is a condition that is unique to hens that are in a high state of egg production, primarily caged layer hens. The cause of the condition is thought to be associated in an imbalance of minerals/electrolytes in the body. Rickets and abnormal bones in adult birds is commonly present. In layers under thirty weeks of age, the cause is usually a temporary calcium deficiency when egg production reaches eighty percent or higher. If intake of calcium does not satisfy the need for egg production, the hen will remove calcium stored in the bones. Ultimately, osteoporosis develops, bones become soft and hens are subject to bone fractures. Crippled and unable to stand, the hen suffers from the caged fatigue symptoms. Many hens show spontaneous recovery if removed from the cages and allowed to walk normally on the floor. This indicates that a lack of exercise may be a partial cause. Cage layer fatigue is more prevalent in single-hen cages than in multiple-hen cages. When two or more hens are caged together, they get more exercise because of competition for feed and water. Supplementation of the diet with phosphate, calcium and vitamin D3 is usually helpful. Adding calcium to young birds by top-dressing the feed with twenty pounds of oyster shell or limestone per one thousand hens will often help the condition. In older hens, calcium deficiency is less likely than phosphorus or vitamin D3 deficiencies. Recommended treatment in these birds is to remove the hens from cages and top-dress feed with equivalent level of dicalcium phosphate. Adding a vitamin/electrolyte supplement to drinking water is recommended in any age bird suffering from this condition. Flocks that do not respond to the above therapy should be submitted to a poultry disease diagnostic laboratory to determine the cause of the problems. Several diseases can cause symptoms similar to caged layer fatigue. Flock treatment for the condition can be prescribed after diagnosis is completed. ==Sources== http://msucares.com/poultry/diseases/dismisc.htm

@wiki::122/ 2008-07-01 2008-07-01T17:47:56Z

==Colibacillosis== '''By Hybro veterinary department - The bacterium Escherichia Coli is present in the gut of every chicken but also in the gut of mammals including humans. The bacterium forms part of the normal intestinal flora that is necessary for the normal functioning of the digestive tract.''' But the peaceful living together of chicken and E. coli can be disturbed and result in colibacillosis. Colibacillosis includes all different outcomes of an imbalance and infection with E. coli. In this article we will give an overview of the factors that can disturb the balance between poultry and Escherichia coli. Opportunist Already in the beginning of the 20th century, bacterial culturing showed the presence of Escherichia coli in the digestive tract of healthy chicken. More recently DNA techniques revealed that E. coli is a minor habitant of the chicken gut. E. coli is one of the hundreds of bacterium species that are present in the gut. Estimations of the number of E. coli are 106 per gram faeces. E. coli is called an opportunistic bacterium that can cause disease at the moment the chicken has an impaired disease resistance. Apart from the host defence mechanisms, the virulence of the present E.coli bacterium and the number of present E.coli bacteria are factors that determine whether the balance between E.coli and the chicken becomes disturbed. When this happens, E.coli can be found on places in the body where it normally does not reside and where it can harm the chicken. Defence mechanisms of the host In the defence against bacterial infections, the host has several mechanisms. The first way of defence is the skin and the mucosal barriers. At the moment these barriers are impaired or damaged, a bacterium can easily enter the body of the chicken. Damages of the skin are for example injuries through cannibalism, artificial insemination, bad litter, unhealed navels and others. Damage of mucous membranes of the respiratory and digestive tract can be induced by viruses, other bacterium species or toxic agents. Examples of viral infections of the respiratory tract are Infectious Bronchitis and Pneumovirus infections. Mycoplasma is a bacterium that damages the respiratory mucosa and presdisposes E.coli to cross the mucosa and enter the bloodstream. A whole list of circumstances can be mentioned that favour the entrance of E.coli into parts of the chicken body that can result in an unwanted E.coli infection. Infection pressure High numbers of the bacterium E.coli can be found in faeces. This means that dirty eggs carry a load of E.coli that can affect the hatchability and liveability of the chicks hatched from the eggs. Also high numbers, up to numbers of 106 per gram, can be found in dust. In bad ventilated houses and in houses that have very dry litter, dust can be a problem. As the chickens inhale the dust, they are exposed to high numbers of the E.coli bacterium. During vaccinations with life respiratory vaccines or at the moment viral infections like Infectious Bronchitis are spreading within a flock, colibacillosis in the form of infections of the air sacs can be the result. Virulence factors There are different methods developed to characterize E.coli isolates. Typing has been done by antibiotic resistance, toxigenicity, presence of adhesionfactors like fimbriae and pilli, hemagglutination and others. Typing of DNA of the bacterium is done with different methods in epidemiology studies. From these studies it is concluded that only few genotypes of the bacterium can be found in the different forms of colibacillosis. These few genotypes can be found worldwide. Many different potential virulence factors have been investigated, but there is no single virulence factor that can be found in all pathogenic strains and is absent in non-pathogenic strains. Therefore it remains questionable whether the virulence of E.coli is an important determining factor in causing disease. Disease symptoms At the moment E.coli enters the chicken body and growths at unwanted places in the chicken, it can cause an infection. Unlike mammalian E.coli strains, the avian pathogenic strains produce no toxins or a low number of toxins. They are therefore relatively safe for humans. At the moment a local infection with E.coli occurs, exudates will be released from the local blood vessels around the spot of infection. The heterophils and macrophages, the phagocytic white blood cells of the host, will migrate to the spot and kill the bacterium. During the infection the exudate turns from colourless fluid to white, yellowish cheese-like material. Bacterium colonies, phagocytic cells and fibrin are present in this caseous exudate. As the bacterium are removed by the phagocytic cells during the inflammation process, which can take weeks to months, the fibrin will be organized and eventually turned into scar tissue. At the moment the bacterium is attacked by phagocytic host cells and falls apart, endotoxins are released. Endotoxins are the lipopolysaccharids that are a structural part of the cell wall of the bacterium. When many E.coli bacteria are present and killed by heterophils, the release of high numbers of endotoxins can cause septicaemia and as a result sudden death. Local or systemic Infections caused by E.coli can stay local or systemic. Local infections are limited to one or more organs of the chicken. A systemic infection occurs when the bacterium enters the bloodstream and spreads through the body via the bloodstream. Known examples of local infections include the navel infection (omphalitis), the oviduct infection (salpingitis), infection of the air sacs (airsacculitis) and infection of the skin (cellulitis). Systemic infections occur when the bacterium spread through the body via the bloodstream. Bacteriaemia is the right word for this situation. Septicaemia describes the situation that bacteria are present in the bloodstream and causes toxic reactions in the host. After the bacterium has been cleared from the bloodstream, some E.coli can hide and colonize in small blood vessels where the bloodstream is low. Examples of such places are the joints and tendons. When the bacterium load is high a systemic infection can result in polyserositis, which includes inflammation of all serous membranes around internal organs like the heart, liver and intestines. Prevention As mentioned above three factors increase the risk of colibacillosis: Infection pressure, impaired host defence and virulent E.coli strains. Prevention should therefore be focused on these three factors. First of all one should strive to minimize the factors that impair the primary and secondary defence mechanism of the host. Minimize the risk of other infections of viruses and bacterium species like Mycoplasma. Mycoplasma gallisepticum infections in broilers are a known predisposing factor for colibacillosis that is seen in the chronic respiratory disease syndrome. Reduce mechanical damage that can be caused by aggressive chicken, artificial insemination, sharp equipment, toxic agents like ammonia and other causes. To minimize the risk of omphalitis it is important to optimize the hatching process to prevent unhealed navels. Too hot temperatures, but also too low temperatures during the hatching process can induce unhealed navels. Apart from damage of the primary barriers like skin and mucous membranes, can also the secondary defence, the immune system of the chicken be impaired by stress. Think about replacements, too high airflows, aggressive males, feeding during moment of laying etcetera. Secondly, the bacterium load should be minimized by implementing good egg hygiene and hygiene in the hatchery in the poultry house. Reduce the amount of dust by sufficient ventilation or wettening of the litter. One can influence the virulence of the E.coli strains only limited. Regular use of antibiotics increases the risk of development of resistant strains. Several vaccines have been developed, but the use of these vaccines have limited effect. In case hygiene and managerial circumstances are not optimal, some effect of vaccination is expected. ==Sources== http://www.thepoultrysite.com/articles/578/colibacillosis-the-imbalance-between-chicken-and-bacterium