Final 7 Flashcards
Cage layer fatigue
Etiology: metabolic disease of laying hens in conventional cages- due to decrease in bone mineral density
Clinical signs
-inability to stand
-fragile bones
-affected birds lie down and stop eating
-egg shells become thin and fragile
-deformed sternum and ribs
Pathogenesis:
-osteoporosis caused by Ca, Phosphorus or Vit D3 deficiency
-deformed sternum and ribs due to inadequate supply of Ca/P during growth
-Acute death due to hypocalcaemia (low Ca )
Prevention/control of cage layer fatigue
- flock uniformity in skeletal and reproductive development
- important to achieve a good skeletal frame in first 6 weeks of life
- avoid excess Ca during rearing until the pre-lay period at which time Ca levles should be increased
- water additives of Ca and Vit D3
- Feed additives: oyster shells
- Newer housing systems
Coccidiosis
etiology: parasitic disease
Clinical signs
-depression, ruffled feathers
-diarrhea or soft mucoid feces
-Morbidity and mortality are variable depending on the species
-poor growth with less pathogenic species
Which form of coccidiosis in birds might have high mortality?
caecal
Prevention/control of coccidiosis
- good biosecurity measures
- remove litter between flocks and clean barn thoroughly to reduce the number of oocysts
- good litter quality through proper ventilation
- laying hens housed in conventional cages that separate the birds from their feces have fewer infections
Necrotic Enteritis
Etiology
-Necrotic enteritis an enteric disease caused by the alpha toxin produced by clostridium perfringens type a and c
Clinical sings
-depression, dehydration, ruffled feathers, diarrhea, sudden death
-subclinical signs include: reduced growth rate and impaired feed conversion
-diarrhea covering the bird’s vet
-depressed birds with ruffled feathers
Pathogenesis
-Initially there is overgrowth of clostridia in the intestinal lumen
-under the anaerobic conditions of the intestine, the toxin is produced and causes necrosis of contact enterocytes
-guts are initially thin-walled and fluid-filled and then become thickened
One of the most economically important diseases of commercial broiler chickens is?
Necrotic enteritis
Prevention and control of necrotic enteritis done by?
- reduce stress in the barn by providing proper ventilation, litter quality, stocking density, lighting
- thorough cleaning between flocks
- vaccination or medication to control coccidiosis
- in feed antimicrobials for prevention or treatment of outbreaks
Infectious bronchitis
etiology: acute, highly contagious respriatory disease of chickens,caused by infectious brochitis virus which is a coronavirus
Clinical signs
-vary and depend on the age of the bird, host immune status and virulence of the virus
-disease can vary from asymptomatic to involvement of the respiratory, renal and reproductive organs
Clinical signs- chicks
- early sings include depression, ruffled feathers, and huddling near heat source
-within 24 hours, signs of respiratory disease can be observed
Clinical signs-birds
-in flocks > 6 weeks of age, signs are similar but may be less severe and may also be subtle
-in laying hens, egg production may drop by up to 50%
-occular and nasal discharge
Prevention and control of infectious bronchitis
- hard to just implement common sanitary and biosecurity measures as iBV is highly infectious
- for farm complexes with multiple flocks always move youngest to oldest
- despite vaccination efforts, outbreaks of IB occur frequently because vaccines aginst one stereotype do not cross-protect against a different stereotype
Fowl typoid and Pullorum disease
fowl typoid: salmonella
-usually seen in grower or adult birds
-affects chickens, turkeys and minor poultry types
Pullorum disease: salmonella
-clinical disease is primarily seen in only young chicks
Bacterial diseases causing high mortality in affected flocks with additional economic losses due to chronic disease
Newcastle disease
Caused by avian paramyxovirus virus Causes high mortality following respiratory and nervous signs or hemorrhage ZOONOTIC POTENTIAL Clinical signs -swelling of the eyelids -occular discharge -conjunctivitis -neurologic signs, such as twisting of the head and neck
What form of newcastle disease is the most virulent and reportable
Velogenic
Avian influenza
caused by orthomyxovirus, type A influenza virus Clinical signs -resp and nervous sings, or sudden death -mortality rate can be close to 100% ZOONOTIC POTENTIAL
Which animals are natural reservoirs of avian influenza?
waterfowl and shorebirds
