Diseases of commercial chickens Flashcards
Commercial chickens are named as ‘chicks’ until what age?
2 weeks old
Commercial chicks are growers until what age?
From 2 weeks to 8/9 weeks
At what age are commercial broiler chickens ‘finishers’?
8/9 weeks
At what age are commercial layers named pullets
10 -17/18 wo
At what age are commercial breeders named pullets
10 - 25/26 wo
At what age are commercial layers named laying birds
From 17/18 wo
At what age are commercial breeders named laying birds
from 25/26 wo
What are some non-infectious causes of high mortality in commercial chicks?
- Temperature/humidity/ventilation
- Water/feeder problems
- Arrived weak and poorly
- Nutritional deficiencies
What are some infectious causes of high mortality in commercial chicks?
- Navel/yolk sac infection e.g. Salmonella spp, E coli
- Aspergillosis – hatchery?
- Vaccine reactions – vaccination at hatchery
- Avian encephalomyelitis
List some immunosuppressive diseases of growers and pullets
Infectious bursal disease virus
Chicken anaemia virus
Marek’s disease
Reoviruses
Mycotoxicosis
What are the clinical signs of Ornithobacterium rhinotracheale (ORT) infection
- Coughing/sneezing
- Reduced weight gain
- Reduced egg production
What are the lesions caused by Ornithobacterium rhinotracheale (ORT) infection?
Air sacculitis
Tracheitis
Bronchopneumonia
How is Ornithobacterium rhinotracheale (ORT) infection treated/prevented?
Antibiotics – amoxycillin, chlortetracycline, macrolides
Vaccine (autogenous)
Biosecurity and management improvements
The acute form of Clostridial enteritis is seen at what age in commercial chickens?
Young chickens
What are the clinical signs of clostrdium enteritis?
Depression, ruffled feathers, sudden death, increased mortality
Subclinical: weight gain, poor FCR
Describe the lesions caused by Clostridium enteritis
Necrosis of intestinal mucosa
Fibrinoectoric enteritis forming a diphtheritic membrane
Avian encephalomyelitis is caused by what type of virus?
Picornavirus
What are the clinical signs of Avian encephalomyelitis?
Tremor of the head, neck and legs
Paralysis
Cataract
Drop in egg production
How is Avian encephalomyelitis treated and prevented?
No treatment
Vaccination available
Which bone is most commonly affected by dyschondroplasia?
Proximal tibiotarsus
What are the 4 influencing factors of dyschondroplasia?
- Genetic selection
- Feed: calcium/phosphorus ratios
- Acid: base balance in feed
- Mycotoxins – reduces the bioavailability of nutrients to the bird
Vitamin D deficiency causes what condition in birds?
Rickets
Describe the grouping of commercial layers vs breeders
Commercial layers – female only groups. Produce eggs that are not going to hatch.
Breeders – produce eggs that will hatch. Females and males live together – natural mating in the house.
Name the 4 most endemic diseases of poultry in the UK
Mycoplasmas
Infectious bronchitis virus
Avian metapneumovirus
Infectious laryngotracheitis
Most cases of peritonitis involve which agent?
E.coli
What are 4 influencing factors of peritonitis?
Flock uniformity
Body weight
Stresses
Sources of bacteria e.g. water, air
How can peritonitis be prevented?
- Sustain body weight and uniformity
- Reduce stress factors
- Minimise bacterial challenges
- Control the primary pathogens via vaccination
- Vaccination against E coli
Egg drop syndrome is caused by what type of virus?
Adenovirus
What are the features/signs of egg drop syndrome?
- About 5-50% drop in egg production, 3-4 weeks
- Shell quality – may or may not be affected
- No increase in mortality
- Lesions – no specific, likely atrophy of ovary/oviduct
How is egg drop syndrome treated/prevented?
No treatment
Vaccine available
