Chickens Flashcards

Question

what is infectious bursal disease?

Answer 1

Infectious bursal disease or gumboro remains one of the most important causes of immune suppression i may broiler producing areas. flocks affected by IBD have reduced responses to vacciation, harsh post vaccinal reactions and increased susceptibility to concurrent and secondary infections. Some of the most common problems associated with clinical or subclinical IBD include - chronic respiratory problems caused by field or vaccine strains of infectious bronchitis and Newcastle disease biruses, secondary bacterial infections caused by E. coli, staph areus, Pasteurella multocida, clostridium septicum, parasitic infections caused by Eimeria, cryptosporidium, severe immunosuppression with IBD occurs prior to or in simultaneous infections with Mareks disease, chicken anaemia and adenoviruses. The disease follows two clinical forms depending on the age at which bids are infected. susceptible chickens younger than 3 weeks of age do not exhibit clinical signs but the infection causes severe permanent immune suppression. clinical signs such as ruffled feathers, fever, trembling, diarrhoea, prostration, mortality an transient immune suppression appear in 3-6 week old birds. several studies have demonstrated that during the first weeks of life the bursa of fabricius actively seeds B type lymphocytes in many secondary lymphoid sites of the immune system such as he spleen caecal tonsils, bronchi. Therefore IBD infections can produce bursal injury and severely compromise the antibody mediated mechanisms of immunity against other disease.

Answer 2

Common cause of mortality in broiler chickens especially during the cooler months of the year. It is due to fluid accumulated in the abdominal cavity as a consequence of heart failure. the disease is more scientifically known as pulmonary hypertension syndrome and this disease may or may not actually end up as ascites. Pulmnary hypertension happens when the heart is unable to push sufficient blood through the lungs thereby significantly increasing the pressure. broiler chickens consume large quantities of feed and grow very rapidly and have a very high demand for oxygen. generally the birds cardiovascular system can accommodate this demand,with the heart efficiently pushing blood through the lungs, where oxygen exchange occurs. there is an increased demand for oxygen, the heart essentially pushes the blood through the lungs harder too increase the amount of oxygen available to the bis metabolism. because the lung volume and cardiovascular volume within the lung tissue is fixe, there becomes a point which the lung can no longer accommodate any blood being supplied to the heart. Maintaining body temperture is one of the more oxygen demanding functions. Air quality also has an impact on the cardiovascular system of broiler chickens. the lungs are capable of extracting only as much oxygen from the air as is available.

Answer 3

Production characteristics of modern poultry lines e.g body weight in broiler chickens place high demands on the skeletal system and inadequacies in nutrition or husbandry will often result in skeletal diseases. skeletal disorders may be primarily infectious or non infectious, both may be seen concurrently within a flock. Skeletal disorders cause lameness from biomechanical dysfunction and in broiler chickens result in poor growht, culled bids, increased mortality an carcass condemnation and downgrading. Bone fractures in spent hens may be a welfare issue. before post mortem examination, flocks should be assessed, live lame birds should b e examined and an opinion as to general flock health, litter quality and management should be formed.

Answer 4

These deformities are often seen as distinct flock problems bones all exhibit some degree or combination of lateral, medial, anterior or posterior bend. they also show some torsion about their long axis. the most common abnormalities are seen in the distal limb and involve lateral or medial deviation or external rotation. Deformity may be a consequence of rickets at a younger age. poor mineralisation of the bone as in rickets, increases the ease of deformation of the bone and therefore the incidence an severity of deformities. rickets may be associate with nutritional deficiencies, enteric disease or malabsorption.

Answer 5

Dyschondroplastic lesions are masses of avascular cartilage extending from the growth plate into the metaphysis and are attributed to the failure of chondrocytes to differentiate. this results in a focal thickening of the growth plate int he proximal tibiotarsus r sometimes the proximal tarsmetatarsus. The lesion in the proximal tibiotarss is often associated with anterior bowing of the tibiotarsus and sometimes fractures below the plug of cartilage. factors shown to influence the incidence and severity of dyschondroplasia include genetic selection, calcium:phosphorous ratios in feed, metabolic acidosis through excess chloride in feed, acid/base balance, and mycotoxins. In a flock of modern broilers, the cause may be marginal inadequacies in dietary calcium or a calcium:phosphorous imbalance.

Answer 6

Rickets develops in growing birds due to a deficiency of calcium or phosphorus or insufficient vitamin D. malabsorption can also cause a mineral deficiency. in rickets, a failure of bone mineralisation leads to flexibility of long bones. sub clinical rickets with only marginal thickening of the growth plates is fairly common and often associated with poor performance.

Answer 7

Ulceration of the metatarsal and digital footpads is a common cause of lameness in meat type poultry. wet or poor quality litter is the common cause, although a biotin deficiency will cause plantar pododermatitis even when litter quality is good. ulcerated footpads may become secondarily infected and caked with litter.

Answer 8

Coagulase positive staphylococci are frequently responsible for bacterial infections in the bones and joints of broiler chickens. mycoplasma synoviae may also play a role in infectious bone disorders and ca be monitored serologically. in broilers, bacterial infections are most common in the proximal femur and proximal tibiotarsus when the bids are >22 days of age. In the proximal femur, the condition is also referred to as femoral head necrosis. Staphyloccal infections in joints and tendons are also seen in breeders. outbreaks are often due to bacterial infection subsequent to an existing tendonitis. a history of other diseases such as coccidiosis is often associated with an increase in staphylococcal infections in breeders. Bacterial bone and joint infections often show a poor response to antibiotic treatment. antibiotics may be used to control the bacteraemia contributing to new cases and to modify the bacterial flora within a flock.

Answer 9

Amyloid arthropathy is usually caused by enterooccus faecalis but not by all isolates. clinical cases are seen only occasionally and are most frequently seen in the hock joint of a few replacement pullets or broiler breeders. unilateral cases may be attributed to the contamination of a previously sterile vaccine diluent with E faecalis during administration if the vaccine is given into the leg muscle.

Answer 10

The presence of bacterially infected yolk material in the coelomic cavity is a common cause of abdominal distension in birds. It is the production disease of birds. Yolk material by itself induces a mild inflammatory response and may be reabsorbed by the peritoneum. because yolk is an excellent growth medium for bacteria, peritonitis may result from secondary bacterial infection. the ceolomic cavity contains the air sacs so E. coli may be sourced in inspired air. localised to diffuse fibrinous peritonitis may result. Egg peritonitis is characterised by fibrin or albumen like material with a cooked appearance among the abdominal viscera. Lodgement of eggs in the oviduct was probably due to reverse peristalsis brought about by breakage of the thin shelled eggs and secondary bacterial infection. peritonitis may also follow reverse movement of albumen and E. coli bacteria from the oviduct into the abdomen. When hens have too many large ovarian follicles, a problem described as erratic oviposition and defective egg syndrome is seen in broiler breeders. The condition is accompanied by a high incidence of double yolked eggs, prolapses of the oviduct, internal ovulation and or internal laying that often results in egg peritonitis and mortality. EODES is prevented by avoiding light stimulation of underweight pullets too early and following body weight and lighting recommendations for each breeder strain. overweight hens may also have a higher incidence of erratic ovulations and mortality associated with egg peritonitis.

Answer 11

It is caused by a herpesvirus that is easily spread within and between flocks and the virus also survives well in the environment. The virus transforms cells and tumours of the liver, spleen and other organs result. almost all poultry flocks are positive for Mareks disease virus, even in the absence of tumours, and represent a risk to young chicks. Direct and indirect contact between poultry and poultry premises by people & vehicles will spread the virus. control is by vaccination of day old chicks and biosecurity. effective application of the vaccine is a job for the hatchery. Currently the most effective vaccines are bivalent vaccines and HVT combinations given at one day of age. Vaccination does not sop infection but decreases tumour formation after infection. After vaccination chicks are not protected until the vaccine strain has multiplied in individual birds and viraemia has been established. therefore chicks should not be exposed to mareks virus challenge for the first 14 days of life and ideally 28 days. Mixed age and multi age rearing farms represent a very high risk of spreading MDV and causing mareks disease. It is not vertically transmitted. only horizontally. vaccination does not stop spread of infection but when effective decreases tumour formation after infection. In feather and skin dust MDV survives very well. chickens become infected by breathing in this contaminated dust. this dust must be completely removed from all vehicles and all buildings between transporting or housing birds. Thorough cleaning must include air inlets and outlets, curtains, all equipment, all contact airspaces. during fumigation of a closed house the ventilation system should also be fumigated. For fumigation the seal should be at the entrance to the ventilation system not where the vents enter the house.

Answer 12

Osteopenia is a consequence of osteooporosis, a deficiency in the quantity of fully mineralised, structural bone. Cage layer fatigue describes a syndrome in which laying hens become paralysed in their cages. The bones of the birds are osteopenic. the sternum is deformed and fractures causes infolding of the ribs at the junctions of the sternal and vertebral prtions. fractures can also occur in the long bones and vertebrae. The medullary bone is osteoomalacic. the syndrome is due in part to a lack of exercise and high egg production but severe problems are associated with inadequate calcium, phosphorous or vitamin D. calcium requirements during growth and before and during lay vary markedly. sources of calcium that enable the slow release of mineral, such as oyster shell appear to give the best results.

Answer 13

S gallinarum and S pullorum. Salmonella is transmitted via the egg from parent to chick. There is a zero tolerance level to salmonella infections in genetic stock, positive flocks are culled and vaccination is not permitted. serological monitoring is most commonly used as a screening test is unvaccinated flocks for sp and sg. The well cleaned poultry house should be a salmonella free environment, everything introduced into the house is a potential source of infection. day old chicks must be sourced from salmonella free parents - this can be confirmed by bacteriological screening of chick box liners. Only pelleted feed or feed containing no animal protein, sourced from a reputable feed supplier should be used to minimise the risk of introducing salmonella.

Answer 14

Starve out syndrome - birds do not eat - due to unpalatable feed, poor brooding temperatures, lack of lighting, poor hatching.. Omphalitis - infection of the navel by bacteria. Rotavirus - transmitted in an egg shell, birds scour/die at 5-7 days of age. Last frothy caecal contents. Salmonella pullorum Salmoonella Binza Coccidiosis - gut parasite of duodenum and caecum. Damages villi and intestinal integrity. Echymoses and lymphocytic infiltration. Birds hunched up and looking for heat. Treat with bayxoc, Amprolium or avatec in feed. Spironucleus - mobile single celled organisms i the mid and lower gut. have flagellae and move rapidly around the slide. Aspergillus fumigatus - fugal disease associated with inhalation of spores from wet beddig. Gapeworm - syngamus trachea - tracheal worms with characteristic outstretched necks and open beaks. found easily at post mortem with red worms in Mycoplasma gallisepticum and cloacalis - seen as sinusitis and eyes closed swollen head often associated with Klebsiella E. coli and staphyloccocus species. cull and treat with tilmicosin. Coronavirus nephritis - viral disease of adults, bronchitis virus. kidney damage and urate deposits. birds die in lay. difficult to treat. Marble spleen disease- adenovirus, blood in lung field and enlarge spleens, engorged. good birds suddenly dead. prevent dindoral - turkey haemorrhagic enteritis.

Answer 15

Salmonella testing of all domestic fowl breeding flocks in the UK was introduced in 2008 as part of a separate EU directive. Producers which produce chicken eggs for eating are also required to test for salmonella and controls are in place if they isolate either salmonella typhimurium, enteritidis hadar, infantis & virchow. If flocks are found to be truly positive for the salmonella then the animal ad health laboratories agency will serve notices on the owners of these flocks. in breeding flocks further action can include compulsory slaughter of the flock or production of an action plan. Heat treatment of table eggs will be required if salmonella is isolated in a layer flock.

Answer 16

It is highly infectious and will attack susceptible birds of any age. it is more important as a threat to poultry than AI. commonly it causes respiratory and nervous signs an can cause a drop in egg production which is an early sign. It can present as a disease with high mortality to one which is asymptomatic. once a bird is infected viraemia occurs rapidly followed by rapid multiplication in most internal organs. The virus can survive in faeces for weeks. It is defined as - an infectious of poultry caused by an avian strain of paramyxovirus type 1 with a intercerebral pathogenicity index in day old chicks of greater than 0.7. On suspiscion of disease a movement restriction is served on the farm which stops all movements of birds, eggs and bird products onto or off the farm. On confirmation of the disease on a farm there is an infected area declared consisting of a 3km protection zone and 10km surveillance zone as a minimum. Once the infected farm has completed its final C& D and 21 days have lapsed it can restock with vaccinated birds. These bids are then cloacal swabbed after day 14 and the swabs are sent for virus isolation. Dead birds found during restocking are also subject to testing.