Disease Conditions in Poultry Meat: Causes, Symptoms, and Lesions
This detailed information by Prof. Dr. Refaat Farghaly discusses various disease conditions in poultry meat, including bacterial, viral, parasitic, and protozoal diseases. It covers diseases such as tuberculosis, fowl cholera, marek's disease, salmonellosis, and coccidiosis, providing insights into causes, symptoms, lesion descriptions, and recommended judgments for affected carcasses.
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Disease conditions in poultry meat Prof.Dr: Refaat Farghaly
III. disease conditions: . Septicaemic carcasses Breast blister Emaciation Oedema & ascites Cannibalism & feather picking ii. Bacterial diseases iii. Viral diseases Tuberculosis Fowl cholera Mareks disease Pseudotuberculosis(ye rsinosis) Avian leucosis complex iv. Parasitic diseases: Salmonellosis Newcastle disease Mycoplsmosis Infectious bursitis (gumboro disease) Laminosioptes cysticola Fowl typhoid Coliform infection Hetrakis gallinae Chlamydiosis Protozoal diseases Histomonas meleagridis coccidiosis
1-Tuberculosis:. Chronic disease of poultry and less commonly in ducks and geese. Caused by the acid fast bacilli Mycobacterium Tuberculosis var. avium and usually occur in older birds. On P.M inspection the disease recognized by: Irregular yellow or yellowish white , caseous or granular nodules which vary in size from pinhead to that of the walnut lesion which are not usually raised above the surface except in the spleen in which the lesion may be raised. The tuberculous lesion are most commonly present in the liver, spleen and in the intestines, although bone marrow, muscles, ovaries and lungs may be affected.
T.B Liver: The lesion is varying in size and in any cases the liver is enlarged and may contain old blood clot. Spleen: Is usually enlarged sometimes to the size of the hen's egg and the lesion protrude from the surface. The digestive tract: Specially at the junction of the intestine with the caecae, nodules varying in size from a millet seed to a golf ball or larger are evident beneath the serous coat of the intestine. These are brownish- yellow in color and projected towards from the intestinal wall on which there is an ulcer. Bone marrow: May be involved in 90-94% of cases particularly the femur and tibia. Judgment: Total condemnation of the affected carcass.
2. Fowl cholera: Highly contagious disease of domestic fowl , turkey, ducks & geese. Caused by Pasteurella multocida ( P. ovisepticum) The disease occur in 4 forms: Peracute Acute (typical fowl cholera) Chronic Localized (wattle cholera)
P.M Lesions: In peracute & acute forms: Peticheal haemorrhages are present on the heart, proventriculous, sternum, gizzard and peritoneal fat. Whitish necrotic foci in the liver. Serofibrinous exudates in the pericardial sac. In the chronic form: There is evidence of nasal catarah and pneumonia especially in turkeys Arthritis. Judgment: Total condemnation of the carcass due to septicaemia. Localized form may be passed after rejection of the head.
3. Pseudotuberculosis: (Yersiniosis) Highly infectious disease of poultry and more important in turkeys. Caused by Yersinia pseudotuberculosis rodentium Acute form: there may be no lesions apart from an enlargement of the liver and spleen. Chonic form: show whitish or yellowish necrotic nodules in the liver , spleen and lungs. Judgment: Total condemnation.
4-Salmonellosis: Poultry and poultry meat play an increasingly important role as a source of human salmonellosis and salmonella food poisoning for human. Contamination of poultry meat with salmonella occur in poultry plant especially when a few infected carcasses were slaughtered and eviscerated in the line system with those which are free from salmonella, therefore, if salmonella infection has been diagnosed in a flock can be allowed to be slaughtered at the end of the day but 2 further actions should be taken: The hygiene in the slaughter plant must be raised to the highest possible standard which required slower rate of machinery. Any carcass showing suspicious lesions which indicate septicaemic or bacteraemic condition should be condemned.
P.M finding: Occasionally in septicaemic birds there is a pericarditis & a fibrinous layer over the liver which is difficult to distinguish from air saculitis, But in most cases , there is no specific P.M finding In other there are necrotic lesions may be seen in the heart, liver and caeca.
In adult hen which affected with Salmonella pullorum or S. gallinarum , the ovary becomes degenerated, the liver appear enlarged , congested & after exposure to air short it develops a greenish-bronze color.
Food poisoning occur after consumption of frozen poultry meat when the carcass storage at high temperature, not completely thawing & inadequately cooked. Therefore the following precautions should be taken to prevent salmonella food poisoning: The frozen carcass must be thawed properly before being cooked. Cooking must be thoroughly to ensure that all parts of the meat are treated. When the meat is not to be eaten must be stored at temperature not more than 4oC for 3 days & when storage for longer period they should be stored at -12oC or lower and before eating it must be heated quickly at least 70oC.
Judgment Bacteriological examination of the carcasses is of important value for judgment, moreover to detect: The percentage of contamination. To detect the total number of salmonella /cm of the carcass skin. Unfortunately no general acceptable figures are recognized for either the above mentioned 2 points. So that it is difficult to interpret the results. Therefore of birds known or suspected to be infected with salmonella should be not be passed for human consumption until cooked.
5. Fowl typhoid: Cause:Salmonella gallinarum. P.M findings: jaundice and brownish discolouration of the serous membranes are present together with enlargement of the liver and spleen. The liver when come or exposed to the atmosphere assumes a distinctive bronzy appearance, lung also is congested and oedematous. In chronic cases grayish areas of necrosis may be seen in the myocardium and intestine. Judgment: Total condemnation.
6-Mycoplsmosis: Air saculitis: Mycoplsma spp. Are responsible for many diseases in poultry as; air saculitis and chronic respiratory disease. P.M findings: Air sac appear cloudy, later become serous exudates which varies in amount, later on the wall of the air sac become thick yellow casious exudates, in some cases similar exudates may be present in pericardial sac. Judgment: If septicaemia is present or affection of the liver and pericardium are involved Total condemnation of the carcass. When only the air sac are affected , the judgment depends on the extent of the affection which either removal or stripping of the air sac or total condemnation.
7. Coliform infection: Infections caused by different strains of Escherschia coli and include; coli septicaemia , coli granuloma and arthritis Coli septicaemia: occur most frequently in broilers, turkey and ducks. P.M findings showed the lesions which varied from typical septicaemia to visceral serositis, air sacculitis, pericarditis, tendosynovitis. Judgment: total condemnation.
8-Coli granuloma is anodular condition involving the intestine, liver and caeca. The granuloma may attain at alrage size resembling tumours. Judgment: trimming of the affected parts.
9-Chlamydiosis: Ornithosis & Psittacosis were at one time used synonymously. Psittacosis is employed for the disease in man and birds" parrot", while Ornithosis refers to the condition of birds other than parrot and man. Chlamdydia psittaci is the cause which is intracellular parasite which occupying position between bacteria & virus. Judgment: when the disease is detected or there is a suspicious at antemortem inspection the birds are not allowed to be slaughtered. The disease has a serious public health significance in that man may become affected.
1-Mareks disease: Caused by herpes virus, the acute from must occur in younger chickens and is much more expolosive and at the begining of outbreak there are more birds exhibiting depressed symptoms than paralysis. Ante-mortem inspection: eye lesion which consists of irregularity of the pupil with some depigmentation. In the classical form the symptoms consists of paralysis of the legs and wings, the typical attitude begin for one leg to be stretched back and the other forward.
Whole carcass inspection: Skin lesion in which the feather follicles affected with distinct whitish nodules which is more often seen in leg and neck. Partially eviscerated carcass inspection: The lesion may be seen in any organs, enlargement of the affected tissue and diffuse grayish discolouration often with nodular tumor like growths, although pinhead-sized lesions may be seen in spleen, kidneys, heart, lungs and liver. In the liver there may be nodular tumors or diffuse infiltration; giving it a coarse granular appearance and there can be cauliflower- like growth in the ovary. Muscle lesion appear in the form of whitish streak or nodular lesion are seen most often in the breast muscle.
Other organs which can be affected, often which single or multiple nodular tumours, are the heart, heart, spleen, kidney, lung, adrenal, pancreas and intestines. Proventricular lesion in the form of thickness of the wall besides increase of firmness of its wall and irregularly thickened, as can be seen more easily on cross-section, when the nerves are affected they appear swollen with the loss of the cross striations. The affected nerve can be 2 or 3 times the normal thickness but they are difficult to see without dissecting them out, so that these lesions are usually seen when affected carcasses are given a particularly thorough post-mortem inspection to assist in marking differential diagnosis, as they only in Mareks disease. Judgment: All carcasses affected with Mareks disease considered unfit for human consumption Total condemnation.
2-Avian leacosis complex: There are 3 leukosis which affect the adult domestic fowl: lymphoid, myeloid and erythroleukosis. All 3 can produce symptom of emaciation, anaemia and weakness in the live birds. At the P.M inspection: The typical picture is an enlarged, friable liver, although other forms can occur.
3-Lymphoid leukosis: . The liver affected can be enlarged grayish and friable or tumors may be nodular or military. Other organs, commonly the spleen and the cloacal bursa, can be affected with tumors of lymoid leukosis which are soft, smooth and grayish and can be difficult to distinguish from some of Mareks disease. Myloid leukosis: characterized by a Morocco-leather- like appearance of the liver, although a nodular form of the disease also occurs. The spleen also is usually affected and tumors can be seen on the interior surface of the sternum, ribs and pelvis. Erythroleucosis: relatively rare and in this disease the liver and spleen are enlarged and cherry-red colour. Judgment: All carcasses affected with any form of the Leukosis disease complex considered unfit for human consumption Total condemnation
4-Newcastle disease It is a disease of world wide distribution and primarily affects fowl. The disease is transmissible to man, occurring usually as a conjunctivitis. P.M lesions: Slight inflammation of the trachea and bronchi, with mild exudation, is commonly present. Cloudiness and yellowish thickening of the air sacs may be a prominent feature. Hemorrhages of the mucous membranes of the proventriculus have been seen in the more acute form. Judgment: Generally, carcass showing a general systemic disturbance. Total condemnation. But when lesions are localized and of such character and extent that there is no systemic disturbances, only the affected parts are condemned.
5-Infectious bursitis( Gumboro): Is characterized by swollen gelatinous bursa and sometimes haemorrhagic. The kidney are swollen and show degenerative changes, muscles are often congested and possibly haemorrahgic. Judgment: when lesions are localized without any systemic disturbances, only the affected parts are condemned. But when the lesion includes the muscles Total condemnation of the carcass.
Parasitic diseases Parasites usually affected the intestines or the skin. One parasite Laminosioptes cysticola, affects the muscles and subcutaneous tissues and renders the carcass unfit for human consumption. Black head in turkey and chickens, which is associated with lesion in the liver and caeca, is associated with the caecal worm Hetrakis gallinae and the protozoal parasite Histomonas meleagridis. in black head , the liver will be unfit for human consumption. Coccidiosis affects the intestinal tract of poultry and in both these disease the judgment regarding total or partial condemnation will depend on the condition of the carcass and organs.
