CHAPTER 53. Poultry Medicine and Management
F. Dunstan Clark
GENERAL INFORMATION
The field of poultry medicine is considered to be a somewhat specialized field because many commercial companies employ veterinarians on staff. Most private practitioners will not be involved in commercial poultry medicine but instead may be called on to assist owners of backyard, hobby, and exhibition flocks.
The commercial poultry industry uses few medications in their birds. However, the industry does employ numerous vaccinations and biosecurity in an attempt to prevent most diseases. Rarely will commercial poultry have nutritional problems, whereas small flock owners may have deficiencies in their birds. Small flock owners often attempt to treat their birds with little if any consultation other than that offered by the local feed store or hardware store employees. In addition, many small flock owners may have great difficulty finding vaccines for use in their flock. Biosecurity practices can be used to assist small flock owners control disease. However, because many small flocks are composed of multiple ages and species, the principles might not work as well as in the commercial industry.
This review outline is a guide for veterinarians in preparing for the poultry medicine examination questions. Information is included to help in the understanding of both the commercial poultry industry and small flocks. Numerous diseases can seen in poultry; the review outline lists those most commonly seen.
POULTRY RESTRAINT
I. Physical
A. Several types of poultry may be kept as hobby pets, including the following: Chickens, turkeys, waterfowl, game birds, guinea fowl, and pigeons
B. Most domestic poultry are reasonably docile and easy to handle
C. Dangers
1. To the handler: Being pecked, scratched, hit by a wing, spurred
2. To the bird: Wing fractures, leg fractures, panic, suffocation, escape
D. Methods
1. Chickens
a. Simultaneously grab chickens by the leg and wing
b. Carry chickens by both legs
c. Hold both legs of chickens and support body with palm of hand
d. Hold chickens next to your body while holding both legs
e. Blindfold the eyes of chicken
f. Interlock wings of chicken over back
g. Care must be taken to not interfere with respiration
2. Turkeys
a. Grasp and hold small birds similar to holding chickens
b. Grasp large turkeys by both legs and allow them to rest on their keel
c. Lift by holding one wing and both legs
d. Do not lift heavy turkeys by their legs only
3. Waterfowl
a. Capture with nets or hooks
b. Support the head and neck of the bird when lifting
c. Can be held with the head tucked under the handler’s arm with the bird’s body against the handler while holding both legs of the bird with one hand
4. Pigeons and quail
a. Usually held in one hand similar to holding a small chicken, with the palm of the hand supporting the ventrum of the bird and the legs held between the fingers of the same hand
b. Birds may also be held in the palm with the ventrum of the bird in the palm and the bird’s feet and legs extended away from the palm
c. Pigeons and quail often escape easily
d. When holding in one hand, care must be taken to not interfere with respiration
II. Chemical restraint
A. Seldom needed in most poultry
B. Ketamine and isofluorane gas are excellent
HUSBANDRY
I. Nutrition
A. Anatomy
1. All poultry have no teeth for grinding food
2. Food is grasped with the beak
3. The crop, an extra thoracic diverticulum of the esophagus, acts as a short-term storage organ for food. Digestion of starch is initiated here
4. Poultry have a muscular stomach (the ventriculus or gizzard) for grinding food smaller
a. HCl converts pepsinogen to pepsin
b. Pepsin digests protein
6. Most digestion occurs in the small intestines
7. Some fiber digestion is in the paired cecae
8. Feces excreted into cloaca
B. Commercial diets
1. Feed is the greatest cost associated with poultry meat and egg production
2. Commercial poultry companies have feed mills to prepare diets
3. Diets are least-cost rations
4. Diets vary between industry segments and poultry companies
5. Poultry diets are usually crumbles or pellets
6. Seldom have diet-related diseases or problems in commercial industry
7. Several diets may be used throughout the life of a flock
a. Starter diet
b. Grower ration
c. Maintenance ration
d. Finisher ration
C. Backyard, hobby, exhibition diets
1. Grains
2. Commercially prepared diets available from local feed store
3. Prepare own diets using grains, supplements, other ingredients.
4. Diets may not be least cost
II. Housing
A. Types
1. Broiler
a. Raised in same house for brooding and grow out
(1) Single age on farm
(2) “All in all out” to reduce disease
b. Length and width vary with company. Trend toward longer and wider houses
2. Commercial table egg
a. Environmentally controlled houses
b. Single- or similar-age farm
c. Birds brooded in one house, then moved to layer house
(1) Moved at 18 to 20 weeks
(2) Chickens are housed in cages
(3) Multitiered cages (more birds per house)
3. Turkeys
a. Similar housing style as broilers
b. House width and length may vary
c. Multiage farms
(1) Brooded in one house for 8 weeks
(2) Moved to grow out house on farm at 8 weeks
4. Backyard, hobby, exhibition poultry
a. No standard housing
b. May be allowed free range on the premise
c. Various ages and species may be on the premises
d. Housing size may vary with the breed kept
(1) Standard-size breeds
(2) Bantams
B. Ventilation
1. Reduce noxious gases, dust, moisture, and pathogens
2. Types
a. Mechanical
(1) Fans in the house to move air in or out
(2) Fans move air from one end of the house (tunnel effect)
b. Natural
(1) Curtain sides that can be raised or lowered
(2) Wire pens instead of solid sides (hobby flocks)
C. Litter and bedding
1. Used to dilute feces, absorb moisture, comfort
2. Usually wood shavings or rice hulls
a. Other substances can be used commercially and in hobby flocks
b. Many hobby flocks are allowed free range to dirt or pasture
3. May be used for more than one flock
4. Typically not used in cage layers
a. Wire floors or slat floors used
b. Manure collected in lagoons or pits or allowed to dry beneath cages
5. Disposal of litter may be an environmental problem
D. Lighting types
1. Natural only: Usually only hobby flocks
2. Natural supplemented with artificial
a. Commercial poultry industry
b. Some hobby, exhibition flocks
3. Total environmentally controlled housing used
a. Maximize egg production
b. Maximize growth and feed conversion
POULTRY MANAGEMENT
I. Broiler industry
A. Genetic stock
1. Male and female lines
2. Obtained from genetic companies
3. White chickens developed as crosses of various meat types
a. Cornish
b. White or barred Rocks
B. Breeder flocks
1. Produce eggs to be hatched as broilers
2. Male and female lines
3. Multiplier vaccinations given throughout life
a. Hyperimmunize progeny via egg yolk
b. Prevent egg production losses
4. Eggs are set in company hatcheries
a. Incubated at 99.5° F
b. Incubation period is 21 days
c. In ovo vaccinated using in ovo technology
(1) 18 days of incubation
(2) Marek disease
(3) Infectious bursal disease
d. Chicks hatch in hatchers
C. Grower farms (broilers)
1. Chicks delivered to farms from company hatcheries
2. Chicks grown under controlled conditions
a. Lighting
b. Ventilation
c. Heating and cooling
d. Feeding programs
3. Chicks brooded in house and grown in same house
4. Processed at 36 to 42 days of age, depending on use
a. Whole bird
b. Further processing
5. Bird totals on farms may be more than 100,000
II. Table-egg industry
A. Genetic stock
1. Male and female lines. Various characteristics from each line
2. Leghorn types: White eggs
3. Rhode Island red: Brown eggs
B. Commercial table-egg flocks (caged layers)
1. Obtain day old pullets from genetic companies or hatch eggs from genetic companies
2. Raise pullets under controlled lighting and feeding programs
3. Pullets moved to environmentally controlled lay houses at 16 to 18 weeks of age
a. Cages
b. Bird per cage density varies
4. Egg production starts about 18 to 20 weeks of age
5. Birds are vaccinated multiple times during their life
a. At time of movement to lay house
b. While in lay house to prevent egg production losses
6. Birds may be molted
a. Molting is a normal process of feather replacement
b. Layers are stimulated to molt
7. Birds are in production 65 to 110+ weeks
8. Many companies have million+ bird complexes
III. Turkey industry
A. Genetic stock
1. Genetic stock originally from genetic companies
2. Breeder flocks produce eggs that are used for commercial (production) turkeys
3. Breeder hens are artificially inseminated
4. Hens usually produce 80 to 100 eggs during a lay cycle
5. Birds are housed in environmentally controlled houses
6. Eggs are hatched in company hatcheries
a. Incubation temperature is 99.5° F
b. Incubation period is 28 days
B. Commercial production flocks
1. Poults obtained from commercial company hatcheries
2. Male and female turkeys are grown separately
3. Brooded in brooder houses until 8 weeks of age
4. Moved to grow-out houses at 8 weeks of age
5. Males usually grown until 18 to 20 weeks of age
6. Females usually grown until 16 to 18 weeks of age
7. Processing age determined by product use
8. Vaccinated multiple times during life
9. Several rations used during life of flock
IV. Backyard, hobby, exhibition poultry
A. Genetic stock
1. Obtained from specialized hatcheries, hardware stores, feed stores
2. Obtained from other hobby flock owners
3. May be pure-bred stock
a. Meat breeds
b. Egg breeds
c. Dual-purpose breeds
4. May be mixed stock
5. Birds may be kept for purely recreational reasons or aesthetics
B. Exhibition stock
1. Many birds are selected for specific exhibition characteristics
2. Investment in these birds may be time and money
a. Often these birds are selected over many generations
b. Value is often more than economics
COMMON POULTRY DISEASES
I. Bacterial diseases
A. Colibacillosis
1. Cause is Escherichia coli
2. Usually is opportunistic
3. Any age or species of poultry can be affected
4. Signs dependent on organ system affected
a. Unthrifty, weight loss, anorexia
b. Diarrhea
c. Respiratory signs (cough, rales, sneeze, gasping)
d. Sudden death without other signs
e. Difficulty walking
5. Lesions
a. Air sacculitis and pneumonia (fibrinous inflammation)
b. Enteritis (reddening of intestine with mucus)
c. Septicemia
(1) Fibrinous exudate on liver, pericardial sac
(2) Petechial hemorrhages on affected organs
d. Synovitis and arthritis
e. Omphalitis
f. Coligranuloma
6. Diagnosis
a. Signs and lesions (presumptive diagnosis)
b. Isolation of bacteria (confirmation)
7. Treatment
a. Antibiotic sensitivity
b. Broad-spectrum antibiotics
d. Many drugs are not approved for poultry
8. Prevention and control
a. Sanitation, disinfection
b. Biosecurity
B. Fowl cholera (pasteurellosis)
1. Cause is Pasteurella multocida
2. May be an acute or chronic disease in poultry
3. Signs: Unthrifty, ruffled feathers, anorexia, sudden mortality, inability to walk, dyspnea, mucoid discharge from mouth, fever
4. Lesions
a. No lesions in some cases of acute mortality
b. Weight loss
c. Septicemia
d. Swollen inflamed joints
e. Swollen face and wattles
f. Pneumonia and air sacculitis
g. Necrotic foci in liver
5. Diagnosis
a. Signs and lesions (presumptive)
b. Isolation of bacteria (confirmation)
6. Treatment
a. Antibiotic sensitivity
b. Broad-spectrum antibiotics
c. Commercial poultry may not be treated
7. Prevention and control
a. Best management practices
b. Sanitation and disinfection
c. Biosecurity
d. Bacterins
C. Infectious coryza
1. Cause is Hemophilus paragallinarum
2. Usually seen in chickens
3. Any age can be affected
4. Signs
a. Serous or mucoid discharge
(1) Eyes
(2) Nostrils
b. Unthrifty, weight loss, anorexia
c. Diarrhea
d. Respiratory signs (rales, cough, gasping)
e. Foul odor
f. Drop in egg production
5. Lesions
a. Catarrhal inflammation of sinuses
b. Swollen face and wattles
c. Conjunctivitis and infraorbital sinusitis
d. Air sacculitis, tracheitis, and pneumonia
(1) Rare instances
(2) May result in condemnation of carcass
6. Diagnosis
a. Signs and lesions (presumptive)
b. Isolation of bacteria (confirmation)
c. Serology
d. Polymerase chain reaction test (PCR)
7. Treatment
a. Antibiotic sensitivity
b. Broad-spectrum antibiotics
(1) Relapses may occur
(2) Cannot not be used in commercial poultry
8. Prevention and control
a. Sanitation, disinfection
b. Biosecurity
c. Bacterins
D. Salmonellosis
1. Pullorum disease
a. Cause is Salmonella pullorum
b. Any age can be affected
c. Usually seen as a problem in chicks and turkey poults
d. Bacteria is egg transmitted and spreads horizontally
e. Rarely a problem in industry
(1) National Poultry Improvement Plan testing
(2) Destruction of positive birds
f. Signs
(1) Usually only in young birds
(2) Depression
(3) White diarrhea
(4) Huddling
(5) Some will show no signs
g. Lesions
(1) None
(2) Enteritis with cecal cores
(3) Emaciation
(4) Necrotic foci in organs
(5) Retained egg yolks
(6) Blighted ova in hens
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