C2-Lanc«sttr Farming, Saturday, August 6, 1994 mil Poi Penn State * Poultry Pointers COMMON CAUSES OF GASTROINTESTINAL DISORDERS OF POULTRY PA*TTY DUNN DVM Animal Diagnostic Lab Dept, of Vet. Sci., PSU Proper function of the gastroin testinal (GI) tract is one of the most critical factors in poultry health and productivity. Optimal growth rate, feed con version, egg production and liva bility are all dependent on a normal alimentary tract, from mouth to vent. The cost of feed represents the highest of all costs involved in pro ducing chickens and turkeys. Therefore, maintaining the integri ty and function of the organ system responsible for digesting and absorbing the nutrients in the feed so that the bird can optimally bene fit from those nutrients becomes a very important economic consideration. Improperly functioning GI tracts “waste" the valuable nutri ents in the feed. The nutrients thus become a liability in the manure rather than a benefit in bird or egg tissue. Many factors or events can con tribute to abnormal or diseased GI tracts. Most commonly, infectious dis ease agents and nutritional factors, including dietary toxins, are thought to be involved; but degenerative conditions, metabol ic abnormalities and traumatic fac tors can not be overlooked. ■V ,/r In fact, many GI diseases are “multifactorial” in nature, mean ing that a combination of insults are involved in causing a particular problem. A closer look at a few of the more common and well documented infectious agents (parasites, bacteria and viruses) and nutritional toxins known to cause gastroenteropathy is warranted. PARASITES •Coccidia are microscopic pro tozoal parasites that can cause major problems in chickens, turk eys, and game birds. They can be found in the manure, litter, and soil wherever poultry are raised. Poultry veterinarians and diag nosticians consider coccidia to be the single most common of all the known causes of enteritis in domestic poultry. Coccidia para sitize the lining of various parts of the intestinal tract and cause inflammation and sometimes bleeding in the affected areas. The resulting clinical disease caused by a moderate or severe infestation is called coccidiosis. Affected birds may appear ill and unthrifty and pass mucoid or bloody feces. Mortality can result from severe infections of the mod erate and highly pathogenic types of coccidia. Even low level infections can cause pale birds with sub-optimal growth and/or feed conversion. Healthy birds raised on litter should be able to mount an immune response to coccidia and live in balance with the parasite after the initial phases of infection. A constant low level reinfection with the parasite is necessary to maintain this immunity. Also the immunity is specific to the particu lar species of coccidia infecting the bird. In the chicken,, for example, exposure to all eight types of chicken coccidia is necessary to protect against all possible coccidia-induced disease. Birds housed on wire will not develop or maintain immunity to coccidia and thus are susceptible to infection if the parasite is intro duced or the birds are moved to the floor where they can ingest litter and feces. Birds with compromised immune systems (Infectious bur sal disease, Marek’s disease, man agement stresses, etc.) may be unable to fight off coccidial infec tions. These birds experience repeated bouts of coccidiosis that respond to therapy but quickly relapse when treatment is removed. A variety of anticoccidial drugs are available for use in prevention and treatment of coccidiosis. Man agement aimed at keeping litter clean and dry is a very important part of control. Vaccines contain ing multiple coccidia species are used successfully in longer lived birds. •Metazoan Parasites or “worms 4 * can infect the GI tracts of poultry and cause enteritis or blockages. Chickens reared in intensive management situations rarely have significant problems with roundworms or tapeworms. Turkeys, however, are exper iencing increasing problems asso ciated with roundworm infesta tion. The roundworm larvae can cause extensive inflammation of the intestine. In addition, there is increasing evidence that some lar vae migrate to the liver where they cause tiny liver spots which are noted at processing time, resulting in liver condemnations. BACTERIA One of the most dramatic exam ples of bacteria-induced enteritis is "necrotic enteritis” caused by an BINS and augers We Will Assemble & Deliver Bins To Your Farm overgrowth of a large, anaerobic bacteria known as Clostridium Perfringens (CP). This organism produces a potent toxin that causes extensive destruction of the intestinal lining resulting in rapid death of the bird. This condition is most common in broiler chickens and relatively uncommon in other types of poul try. CP can be found in low num bers in normal birds, but dietary factors and/or previous parasitism by coccidia or other intestinal injury can cause changes that enhance the growth of CP and allow it to damage the intestine. Antibiotics, particularly bacitra cin, are used to treat necrotic enteritis. Corn/soy based diets, regular feeding schedules, effective cocci diosis control and inclusion of feed-grade antibiotics in the ration help prevent the condition. Certain strains of Salmonella and E. Coli bacteria are well documented causes of enteritis in many mammalian species. The association between these organisms and intestinal patholo gy is much less clear in poultry. Many types of E. Coli are found in normal chicken and turkey intestines. Poultry, like mammals, can be non-symptomatic carriers of Sal monella as well. These bacteria (E. Coli and Salmonella) tend to cause illness only when the birds are very young or when the intestinal tract is damaged by some other cause, thereby allowing passage of the bacteria into the blood stream. An overwhelming bacterial sep ticemia can result in sickness and death. Other bacteria such as spiro chetes and “long segmented filamentous bacteria” have been associated with cecal and small intestinal pathology, respectively. However, clear-cut causQ |. effect relationships have not been established. Hemorrhagic enteritis (HE) is a well-documented disease of turk eys directly caused by adenovirus infection. In the classic form of HE, blood is found in the upper part of the small intestine due to destruction of the tips of the villi, the microscopic, finger-like pro jections of the intestinal lining. Most HE infections today are We Stock Truckloads Of Chore-Time Bins & Miles Of Chore-Time FLEX-AUGER Authorized master distributor since 1982 Northeast Agri Systems, Inc Flyway Business Park 139 A West Airport Road Litltz, PA 17543 Ph (717)569-2702 VIRUSES Store hours Mon -Frl 7 30 to A 30 Sot 8 00 to Noon 24 Hr 7 Day Repair Service 1-800-673-2580 51 subclinical, with very little, if any, bleeding. Death attributable directly to the HE virus infection is rare in this sub-clinical form. However, inflammatory changes are present in the intes tine, and the infection results in a transient immunosuppression that may allow an increased incidence of E. Coli septicemia. Most breeder and commercial turkeys are vaccinated with an attenuated live form of HE vims to prevent field infection. A potentially fatal condition of domestic and wild ducks called duck vims enteritis (DVE) has been diagnosed in our state several times in recent years. This disease is caused by a her pes vims that induces necrosis and hemorrhage in the large intestinal and cecal lining, as well as in lym phoid tissue. Infected, recovered birds may become carriers of the vims and shed vims unpredictably during periods of stress to other suscepti ble ducks. A vaccine has been used in commercial Pekin ducks on a limited basis. Vaccination is not commonly practiced as eradication is the preferred method of control. VIRUSES SUSPECTED Many different viruses have been suspected of playing a role in the development of enteritis, so called “malabsorption syndrome.” “pale bird syndrome,” and “runting/stunting syndrome.” Reoviruses, rotaviruses, coro naviruses, parvoviruses, entero like viruses, calicivirus, and ade noviruses (to name a few) have all been detected in intestinal tracts or feces from birds exhibiting clini cal symptoms of maldigestion or malassimilation. Unfortunately, there are few, if any, studies in which purified virus preparations have reproduced the clinical syndrome as it is seen in ,-the field. SYNDROMES Again, it is likely that multiple factors, of which virus is only one, are necessary to cause these dis ease “syndromes.” Much research effort has been directed in this area. Recently, Penn State research ers have shown that a particular strain of coronavirus is likely involved in stunting, enteritis and (Turn to Pago C 3) Put ’em Up! Custom Applications Wl B NOW OPEN MD. SOC UNIVERSITY AVE. (Formerly Long Lumttor) 410-754-9434 STORE HOURS; 7:30 A.M.- 4P.M. Monday - Friday
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