The following is copy of my notes during a seminar on The Role Of Maintaining Respirator Tract Integrity In Preventing Bacterial (CRD) And Viral Infections (AI, ND, IB) by Dr. Gary Butcher, DVM, MS, PhD; Diplomate, American College of Poultry Veterinarians; Professor, Poultry Medicine, College of Veterinary Medicine, University of Florida, USA held in Ortigas. Enjoy!
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In the United States the cost of medication and vaccination is $ 0.09 centavos per pound of broiler.
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Most common diseases of broiler in 1993 in USA:
IBD
E. coli infection
Air sacculitis
Sudden death
Necrotic enteritis
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Most common diseases of broiler in 2003 in USA:
Air sacculitis
Infectious peritonitis
Gangrenous dermatitis
Infectious bronchitis
Leg problems
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Data on diseases in USA can be found on www.rennierassociates.com
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In USA, poultry production is completely integrated. Companies do not own farms themselves. As a result, occurrence of diseases is minimized because of less movement of equipments, animals and people between farms. Tyson in USA does not have their own farm.
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Outbreaks of diseases that occurred in USA are:
Viscerotropic velogenic Newcastle disease among fighting cocks in 2002-03.
Low pathogenic avian influenza
H6N2 – 1996
H7N2 – 2003
H5N2 in Texas
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Pathophysiology and Handling of Avian Respiratory Diseases in Modern Poultry Production
Avian diseases are relatively easy to solve.
The hard part is the identification of disease because diseases are mostly caused by many factors.
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Parts of respiratory system of birds:
Nostril
Sinuses
Pharynx
Trachea
Lungs
Air sacs
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Air temperature is increased upon inhalation. Air passes through cilia and dusts are filtered naturally. The air then goes to primary bronchi and to the air sacs.
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Birds have no diaphragm unlike mammals. So during inspiration birds just take in the air and no exchange of gasses happens. Gas exchange happens during expiration. This makes the birds more efficient in exchanging gasses. The exchange of gas from blood and lungs is termed as “counter current”.
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Air sacs do not have blood supply so if infectious organisms come in, blood cells cannot go there to fight infection.
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Development of the respiratory system did not “keep at pace” with genetic advances in body weight gains.
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Focus of genetic was more on body mass.
This made the heart and lungs un-proportional with the body of broilers.
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This makes broilers more fragile now than earlier breeds.
Broilers now have limited ability to cope with stressors, thus they are more susceptible to the following:
Ascites
Heart attack
Heat stress, dust and ammonia
Mortality following respiratory disease and its complications.
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Proper respiratory function is essential to achieve production objectives.
Factors that contribute to ascites:
Altitude
Fast growth
Failure of heart
Heat
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A remedy for ascites is to regulate growth rate with use of mash feeds and feed restriction during day time in hot weather.
A better environment should be provided.
Decrease amount of dusts in the air.
Decrease ammonia.
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During hot conditions birds pant and spread their wings, an indication that they are not comfortable. And when they do, they spend much energy for panting and raising their wings. SO instead of energy going to growth, energy is just wasted.
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Respiratory diseases of broiler
Primary: affects body weight, with high mortality, lowers FCR, increases number of condemns.
Newcastle disease
Bronchitis
Avian influenza
Mycoplasma
Infectious laryngotracheitis
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Most respiratory disease in broilers happens secondary to vaccination complications.
Mycoplasma infection plays a major role in the development of complications.
Mycoplasma is endemic in most regions and is also transmitted vertically.
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IBD or ND field/vaccination reactions and Mycoplasma
Damages tissues and the immune system.
It also allows invasion of E.coli into broiler tissues.
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Mycoplasma targeted treatment:
Prevents excessive reactions by controlling Mycoplasma,
Decreases antibiotic (broad spectrum) cost.
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Success of vaccination is dependent upon the following factors:
Administration of the right vaccine.
Use of proper techniques.
Timing.
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Effects of ND and IB in susceptible broiler:
Decreases body weight and uniformity
Makes FCR higher
Increases number of condemns
Increases medication cost.
And therefore, increases cost of production.
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Vaccination cost is affected by the following:
Purchasing
Vaccinators
Loss of flock performance, because ND and IB cause mild form of disease
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Vaccination should only be done if risk of disease occurrence is high.
The program should be based on specific risk and the location of the farm.
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After a vaccination, birds normally show vaccine reaction:
Mild respiratory reaction 2-3 days after vaccination which lasts for 4-6 days.
Snicks, head shaking, wet eyes, decreased activity and huddling.
But this is self-limiting.
It also varies among farms.
Reaction is necessary to stimulate the immune system. This means that the vaccine virus is replicating.
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Absence of vaccination reaction means:
Inactivation of live vaccine during administration.
Missed vaccination.
Lack of minimal infective dose.
Sufficient immunity at the time o vaccination.
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Excessive or rolling reactions:
Greater duration and intensity.
This is commonly reported so cause must be investigated.
Antibiotic therapy may be needed.
This may lead to losses.
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What leads to excessive vaccination reactions?
Mycoplasma gallisepticum or synoviae
This limits vaccination options due to complications.
Use only absolutely necessary vaccines.
Vaccinate earlier (than 3rd week).
Use less invasive routes and vaccines.
Coordinate vaccination and antibiotic therapy.
Vertical (egg) transmission is less than 2% (low).
Horizontal spread happens in around 3 weeks of age.
Vaccination prior to 14 days decreases complications.
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Treatment
Antibiotics (Tilmicosin) for days 1, 2 and 3 (syempre sila ang sponsor!)
Antibiotics for 1-3 days following vaccination.
Antibiotic selection:
Use Mycoplasma targeted antibiotics
This helps in decreasing resistance development of other bacteria to antibiotics.
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IBD
IBD causes immune suppression.
ND decreases vaccination response. It is also highly persistent.
IB has high vaccine virus persistence but decreases resistance to challenge.
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Invasiveness of vaccination route
Fine spray > coarse spray > Eye drop > Water
Spray droplet size
Initial vaccination: ~100 microns
After priming: ~50 microns
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Water
Should not be more than 1-2 hours
Less time: many will not be able to drink.
More time: vaccine may be inactivated
In more than 1 hour viability is decreased by 50%.
Practice run should be done to test quantity of water needed.
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Management factors affecting severity of vaccination reaction
Chick quality
Unhealed navel
Aspergillus
Dehydration
Omphalitis and others
Uniformity of vaccination dosing
Housing down time and clean out
Age of vaccination
The higher the age the greater the reaction due to the decrease of maternal antibodies.
Chilling, heat stress and temperature fluctuations
Combined respiratory vaccines
Brooding (air and litter) temperature
Litter management, bacterial load and moisture of litter.
Air quality
Ammonia
Dust
Relative humidity
Water quality
Bacterial contamination, minerals, toxins and temperature.
Hatchery sanitation
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Ang cost of production ng broiler minsan (pabagobago kasi) umaabot ng 55 pesos per head!