Infectious Bronchitis (IB) with Com ...

Infectious Bronchitis (IB) with Completed Vaccination Program or Mild Strain in Laying Hens

Infectious Bronchitis (IB) with Completed Vaccination Program or Mild Strain in Laying Hens

Infectious Bronchitis Virus (IBV) in unprotected laying flocks, egg production declines rapidly and egg quality are seen in addition to respiratory signs. Infectious bronchitis virus, however, has been isolated in layer flocks with slight production drops and the production of pale unpigmented shell eggs, but no respiratory signs. 

The severity of the production declines may vary with the period of lay and with the causative virus strain. Six to eight weeks may elapse before production returns to pre-infection level, but in some cases, this never attained.  In addition to production declines, the number of eggs unacceptable for grading is increased and soft-shelled, misshapen, and rough-shelled eggs are produced.

Internal quality eggs, as observed when breaking fresh eggs on a flat surface, may be inferior. The albumen may be thin and watery without definitive demarcation between the thick and thin albumen of normal fresh eggs. Watery white or white Haugh unit decreased score should be 70 below 50 is poor. The chalazae are often broken so that the yolk floats free.  Small hemorrhages may be seen in the albumen or yolk and loose air cell.

Observed Clinical Signs Happenings

Egg drop

  • Egg production declines gradually
  • Some field strains produce a slight production drops and the production of pale unpigmented shell eggs and some slight misshapen eggs
  • In unprotected flocks (unsatisfactory vaccination), the drop in egg production may exceed  50%
  • In flocks well-vaccinated but challenged with field strains which those vaccines do not provide complete  protection, the disease may present as failure to lay at full potential or production falls of up to approximately 10%
  • With mild drops in production, a normal level of production can be restored in 1 or 2 weeks.
  • The severity of production declines may vary with the period of lay

Respiratory  

  • Respiratory signs may or not be exhibit or manifest
  • Respiratory signs spread Slow
  • Coughing
  • Sneezing
  • Trachea rales
  • Respiratory signs may or may not be present or detected
  • In some cases, the respiratory signs may be detected only at night, when the flock is resting
  • The respiratory signs also can be absent or very mild, even in cases of clear production drops and the production of eggs with pale, unpigmented shells

Shell quality

  • Pale or loss of colour in pigmented shell eggs
  • Misshapen eggs
  • A co-infection of Infectious Bronchitis virus increased the percentage of eggshell apex abnormalities caused by Mycoplasma synoviae
  • The shell abnormalities may last the entire production cycle

Internal Egg quality

Internal quality eggs, as observed when breaking fresh eggs on a flat surface, maybe inferior:

  • The albumen may be thin and watery without definitive demarcation between the thick and thin albumen of normal fresh eggs (often encountered in misshapen eggs)
  • Watery albumen with yolk separated from the thick albumen
  • Watery white or white Haugh unit decreased (score should be 70 below 50 is poor)
  • 10 weeks after infection Haugh units  and albumen high was lower
  • The chalazae are often broken
  • The chalazae are often broken so that the yolk floats free
  • Internal eggs abnormalities may last the entire production cycle
  • Prolonged effects in the albumen quality
  • Long-lasting negative effects on the egg internal quality

Infectious Bronchitis (IB) with Completed Vaccination Program or Mild Strain in Laying Hens DOES NOT show, exhibit or manifest any of the following clinical signs happenings:

  • Mortality above the standard
  • Visibly sick birds
  • Flock behaviour activity change
  • Droppings abnormalities
  • Neurological Nervous
  • Lameness or unusual movements, incoordination, reluctance to move
  • Eyes abnormalities
  • Head, Comb, Wattles, Face, Nostrils, Sinuses, Mount, Beak, Earlobes, abnormalities (except eyes)
  • Body Parts (Neck, wings, breast, abdomen, shanks, legs, hocks, feet, joints, vent, and skin, abnormalities), skinny body, retarded growth, weight depression
  • Feathers abnormalities
  • Feed Consumption Changes
  • Diet or Feed Changes (Recent Feed delivery, Recent formulation /diet, Other silo or improper storage, another feed brand)
Causing Agents
Viral infection. Coronavirus Group 3 of the Coronavirus genus
Affected Systems/Organs
Respiratory, reproductive and urinary systems
Spread
A highly infectious virus that spreads bird-to-bird. Direct airborne transmission of virus particles from the respiratory tract is the most common method of spread. Infected droppings and contaminated objects can also spread the virus
Mainly Affects
Faecal Moisture Wet litter/manure and Performance
Solution
Adequate biosecurity. Hens can be protected through vaccination
Suggested Actions
  • Can be confirmed with clinical signs and gross lesions
  • Technical assistance recommended
  • Can be managed with feed additives, off-the-shelf medications
  • Can be managed with vaccination programs
  • Diagnosis should be confirmed with rapid assays and/or a certified laboratory
  • Veterinary intervention is recommended
  • Can be managed with vaccination programs.

Impact on Egg quality

3

Impact on Liveability

0


Impact on Production

2

Overall Economic Impact

2



  1. Y.M. Saif.2008.Disease of Poultry. 12th Edition. page 123
  2. David E. Swayne. 2013. Diseases of Poultry 13th Edition. page 145
  3. Mark Pattison, Paul F. McMullin, Janet M. Bradbury. Dennis J. Alexander. 2008. Poultry Diseases. 6th Edition. page 342

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