Chickens

Question 1

how can egg eating be prevented?

Answer 1

Provide plenty of nest boxes and ensure they are nice and dark, with eggs removed daily. if they are raised above the birds eye level it will discourage them spotting the eggs. placing in china eggs or ping pong balls in nests may help as birds will get fed up from no reward. filling an empty egg shell with mustard and chilli powder may discourage furhter pecking.

Question 2

What are yolk sac infections?

Answer 2

Occur in the first week of life. birds are small, dull, hunched and inactive. such chicks never recover and are best PTS. definitive diagnosis is by PM . look for inflamed yolk sacs with foul smelling contents and septicaemic signs i.e fevered carcases, inflamed livers and spleens. Swabs should be taken for bacteriology. antibiotic treatment may save mildly affected flock mates and may protect the other chicks. consider lincospectin or amoxycilin. prevent by ensuring that only clean unwashed eggs are incubated, ensure brooding environment is clean including water.

Question 3

How can you prevent starve outs?

Answer 3

They are small and dull with empty crops. Consider using electrolytes. Ensuref resh food and water is readily available. Ensure correct brooding conditions. On PM these chicks have dehydrated carcases (dark muscle and urates in the ureters. Empty crops with some litter may be seen. Fatty livers and enlarged gall bladders.

Question 4

How does coccidiosis affect chickens? How should it be treated?

Answer 4

AFfects chicks from 2weeks to 2 months or ex battery hens. caused by eimeria. there are several species each varying in pathogenicity and predilection site. the species involved doesn’t affect the diagnosis or treatment. birds are dull, hunched with ruffled feathers. Have diarrhoea often & blood. Intestinal haemorrhage often. Causes anaemia. often a flock problem. Diagnosis is by clinical signs and faecal oocyst counts. Treatment - first use an anti coccidial drug e.g baycox. control the growth of harmful bacteria with antibiotic treatment such as amoxycillin or denagard. Support the bird/TLC and multivitamins.

Question 5

What antibiotic has a zero egg withdrawal?

Answer 5

Tiamulin

Question 6

Which worms can affect chickens?

Answer 6

Worms can cause problems to bird and egg production - anaemia, weight loss, ill thrift. Ascarids - round worm, intestinal. Capillaria - hair worm, crop. Heterakis - caecum. Syngamus trachea - gape worm. Worm spring and autumn using flubenvet or do routine WECs.

Question 7

What are your differentials for a sneezing hen?

Answer 7

Infectious bronchitis, mycoplasma gallisepticum, avian rhinotracheitis, infectious laryngiotracheitis, newcastles disease, avian influenza, gapeworm (rare in backyard birds).

Question 8

What is a blind layer?

Answer 8

Caused by a malfuncitoning oviduct . yolks are not collected by the oviduct and enter the abdomen. are absorbed slowly. can temporarily be caused by stress or coming into lay. tis resolves itself. permanent oviduct damage such as that caused by juvenile IB infection can cause permanent internal laying which leads to yolks building up in the abdomen causing abdominal enlargement. this may cause the bird to an adopt an upright stance.

Question 9

What is mareks disease?

Answer 9

A herpesvirus. first virus to be associated with neoplasia. often in young birds 3-5 months old, acute associated with neoplastic changes of the liver and spleen, leading to poor growth, diarrhoea and dullness. The classical form is associated with ataxia and paralysis especially of the legs and wings.

Question 10

What is the scaly leg mite?

Answer 10

It is microscopic, burrows beneath the leg scales. IT causes white crusting and raised leg scales also swelling and bleeding in some cases. crust is a mixture of excreta and skin flakes. it is very irritating to the bird. More common in older birds -t reatment is to wash legs and dry, use baby shampoo and a soft tooth brush. dunk the legs into a jar of surgical or methylated spirit. soften leg scales bya pplying vaseline. do this weekly to sooth the legs and keep the mites at bay. Ivermctin drops also work and will worm the bird also.

Question 11

What is Newcastle disease?

Answer 11

A Virus carrie potentially by most avian species. It can invade and replicate in all tissues if virulet. low virulence strains are restricted to respiratory or enteric tracts. also defined by spectum of organs affected:viscerotrophic, neurotrophic,mesogenic, lentogenic or asymptomatic, The initial source is wild birds or their droppings,

Question 12

What is avian pneumovirus?

Answer 12

an RNA virus, classically causes a sinusitis with secondary bacterial infection of the spongy bones of the head causing swollen head syndrome. Clinically seen only associated with pale eggs and a loss of production. secondary nervous signs.

Question 13

what is infectious bronchitis?

Answer 13

A coronavirus - every IB infection starts in the trachea- respiratory disease. IB gets into blood. reaches kidney & oviduct. causes shell thinning, loss of colour and irregularities. in young birds can cause the oviduct to develop with cysts and be non functional. some strains give serious kidney damage. virus is highly contagious and shed from respiratory tract and in droppings.

Question 14

what is fowl coryza?

Answer 14

Haemophilus paragallinarum - highly contagious cause of swollen sinuses and a slight nasal discharge.

Question 15

What is pasteurellosis?

Answer 15

Generalised septicaemia with high mortality due to pasteurella multocida - chronic forms may have swollen wattles. Spread by rodents and infected birds. Treatment with antibiotics is often of limited success and vaccination is likely to be practiced where pasteurella is a problem. Other strains may be found but are often co infecting with E. coli.

Question 16

What is avian mycoplasmoosis?

Answer 16

Mycoplasma gallisepticum and mycoplasma synoviae are bacteria without cell walls that infect chickens and other birds and in some circumstances cause disease. some infections are clinically silent but probably still involve a production penalty due to decreased total number of eggs/chicks or decreased broiler performance. MG is usually more likely to cause disease than MS but there is a wide variation within each species between strains in many characteristics including virulence and kinetics of the serological response. When mycoplasma gallisepticum causes clinical disease it is usually respiratory disease. In uncomplicated infections this could be seen grossly as air sacculitis. MG and MS can both exacerbate respiratory diseases interacting with respiratory viruses, dust, ammonia and opportunistic bacteria. In this case chronic respiratory disease is triggered and mortality may be elevated. Good air quality and the implementation of minimum ventilation have a protective effect.

Question 17

What is the best way of testing for mycoplasma infection?

Answer 17

Culture and PCR testing are the best confirmatory tests available. Swabs are taken from the trachea or cloanal cleft and placed ito mycoplasma media and sent quickly to the laboratory. PCR testing can be done on this sort of sample or on air dried swabs. MG and MS infection is usually detected in the RSA or ELISA. testing is usually recommended to be every 2-3 weeks in high risk areas. This allows eggs to be pulled from the hatchery before they have hatched and spread the infection if there is a problem.

Question 18

What is fowl pox?

Answer 18

Pox like lesions around the head, mouth, oral cavity and cloaca. Pox virus spread by biting insects and is not found in the UK. control is by a wing web vaccine. Oral ulcers are also see with some mycootoxins in feed and can also be caused by very dusty feed resulting in an oral hygiene problem and secondary ulcers. In the case of fusarium mycotoxins ulcers may also be seen in the gizzard and some inflammation in the wall of the proventriculus.

Question 19

What causes gizzard lesions?

Answer 19

Localised lesions with little else apart from poor broiler growth are seen with group 1 adenovirus infections. Histopath shows basophilic intranuclear inclusion bodies.

Question 20

What is necrotic enteritis?

Answer 20

A condition usually of broiler chickens with necrosis of intestinal villi, usually i the duodenum or jejunum and associated with overgrowth of clostridium perfringens.

Question 21

How can viral enteritis in broilers be controlled?

Answer 21

Viral enteritis in broilers is associated with ROTA D and enterolike viruses. other viruses such as reo viruses, astroviruses, small round viruses and circoviruses have also been reported with viral enteritis. Clean out and disinfection between flocks must be sufficient to remove viruses. most enteric viruses are very robust and difficult to destroy. the presence of faecal material increases their stability in their environment and their resistance to disinfectants. Rota viruses are resistant to many disinfectants including qauternary ammonia, chlorhexidine, gluconate and povidone iodine. suitable anti viral disinfectants include formaldehyde, peroxide, peracetic acid and gluteraldehyde. Effective cleaning must be within house an surrounding house. biosecurity is paramount and people clothing or equipment that may be carrying virus must not have contact with birds.

Question 22

Describe coccidiosis in broilers?

Answer 22

Coccidial challenge remains a common cause of poor performance and wt litter. with clinical coccidiosis there may be blood on droppings and unlike some other enteric conditions the bird may appear dull or sick and reluctant to eat or move. symptoms are a conseqence of the damage done to the gut wall during the multiplication stages. coccidial infection is most commonly seen in broilers after 3 weeks of age. the rate of multiplicatio of oocysts is massive and a very small number of oocysts can multiply to a potentially overwhelming challenge in 5-7 days. When assessing coccidiosis in broilers lesion scoring is often used. the pathology of the duodenum and upper si, mid gut, ileum and caeca is all scored on a scale of 0-4.

Question 23

What is dysbacteriosis?

Answer 23

Presence of an abnormal balance of enteric bacteria. associated with wet litter or litter going off and pale droppings with undigested feed between 20 and 30 days of age. Foamy caecal droppings, glistening or orangey droppings and big splashes of caecal droppings ca usually be foud. the litter often has a slippery surface. birds may flick whole feed particles or pellets from feed pans and undigested feed may be seen in droppings and in the intestines. there are also fluctuations in water intake. Water can easily be squeezed out of the droppings whereas normal droppings can be rolled in the hand and they stay intact.

Question 24

What does brachipra cause?

Answer 24

Foamy cappucino type droppings in free range birds and occasionally in barn type systems. enteritis is mainly in the caecae, which contain similar foamy material. fresh smears from gut wall when looked at through microscope can aid with diagnosis. they are also used for spiroucleosis in game birds.

Question 25

what is infectious bursal disease?

Answer 25

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.

Question 26

Why does ascites occur in broiler chickens?

Answer 26

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.

Question 27

how do skeletal disorders occur in broilers?

Answer 27

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.

Question 28

What are rotational and angular deformities seen in broilers?

Answer 28

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.

Question 29

What are dyschondroplasias?

Answer 29

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.

Question 30

What are rickets caused by?

Answer 30

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.

Question 31

What is the cause of plantar pododermatitis?

Answer 31

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.

Question 32

What infectious skeletal disorders may occur in broilers?

Answer 32

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.

Question 33

What causes amyloidosis?

Answer 33

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.

Question 34

What is egg yolk peritonitis?

Answer 34

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.

Question 35

What is mareks disease?

Answer 35

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.

Question 36

How does osteopenia occur in birds?

Answer 36

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.

Question 37

How is salmonella transmitted? which salmonella infections are most common in broilers?

Answer 37

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.

Question 38

What are the most common diseases of gamebirds?

Answer 38

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.

Question 39

Describe the salmonella national control plans?

Answer 39

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.

Question 40

What is Newcastle disease?

Answer 40

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.