Comprehensive Poultry Science: Definitions, Production Systems, Housing, and Anatomy

How would you define "poultry" versus just birds?

Poultry refers specifically to domesticated birds kept by humans for agricultural purposes — primarily for meat, eggs, or feathers. All poultry are birds, but not all birds are poultry. Common poultry are chickens, turkeys, geese, ducks

What are the main poultry products in Canada, which animals make them, and what are the associated production systems?

• Table Eggs: produced by layer hens

• Broiler meat: produced by broiler chickens

• Turkey Meat: produced by commercial turkey strains in turkey barns.

• Hatching eggs: produced by broiler breeders or layer breeders

How would you define an "integrated production system"?

• An integrated production system is one where a single company controls multiple or all stages of the production chain.

• In poultry, this typically includes: breeding/genetics, hatcheries, feed mills, grow-out farms, processing plants

• allows tight control over quality, biosecurity, cost, and consistency

How would you explain a "supply managed production system" to someone with no agricultural background?

Supply management is a system where the government controls how much of a product can be produced nationally, to match supply closely with consumer demand. It causes a stable, predictable income for farmers and stable prices for consumers.

Some disadvantages are that quotas are expensive to buy so its hard for new farmers to enter

What is a quota? What does it mean to a producer? Who decides how much quota is available?

• A quota is a licence that gives a farmer the legal right to produce a set amount of eggs or poultry.

• To the producer: You cannot legally produce without owning a quota. Quota can be bought, sold, or leased and has significant monetary value.

• Who decides: National and provincial marketing boards (e.g. Egg Farmers of Canada, Chicken Farmers of Canada) set total quota levels based on consumer demand forecasts.

What are the different housing systems used for layers in Canada?

• Conventional Cages (battery cages) — being phased out.

• Enriched/Furnished cages: larger cages with perches, nest boxes, scratch pads; replacing conventional cages.

• Aviary Systems: multi-tier indoor housing with free movement, perches, nest boxes, and litter.

• Free Run: birds move freely inside a barn on litter (no outdoor access).

• Free Range: Birds have access to outdoor range in addition to indoor space.

• Organic— free-range with certified organic feed and management.

Who lays the fertile eggs that hatch into broiler chicks?

Broiler breeder hens lay fertile eggs. Broiler breeders are a special parent flock — they carry the same fast-growth genetics as commercial broilers but are managed reproductively to produce fertile hatching eggs.

Males (broiler breeder roosters) mate with or are used to artificially inseminate the hens.

Why do turkey breeders require artificial insemination rather than natural mating?

Commercial turkeys have been selected so intensively for large breast muscle that the tom's body is physically too large to successfully mount and mate with a hen naturally.

AI is the universal standard — semen is collected from toms manually, evaluated, diluted, and inseminated into hens weekly throughout the laying cycle.

If you were to domesticate an animal, what key factors would you consider for selective breeding?

Personality: is the animal calm and manageable around humans?

Diet: Can it be fed economically on available resources?

Growth rate: Does it reach productive size or maturity quickly? Reproductive rate: does it breed readily and frequently in captivity?

Social structure: Does it tolerate living in groups (dominance hierarchy, not territorial)?

Lack of flight response: does it remain calm rather than panic and injure itself?

Which species is acknowledged as the ancestor of domestic chickens?

The RED JUNGLEFOWL (Gallus gallus), native to South and Southeast Asia. Domestication is believed to have begun approximately 8,000 years ago in the region of present-day India, China, and Southeast Asia.

What key changes occurred between 1920 and 1960 in poultry breeding/genetics, housing, and nutrition?

BREEDING & GENETICS: Shift from farmyard mixed flocks to commercial strains; development of hybrid lines; beginning of divergent selection for layers vs. broilers.

HOUSING: Move from outdoor/free-range systems to large-scale indoor confinement housing; introduction of battery cage systems for layers; controlled environment barns.

NUTRITION: Discovery of vitamins; formulated commercial feeds replaced farm scraps; understanding of protein and amino acid requirements.

Can you label the parts of a chicken's digestive tract?

BEAK → picks up feed.

OESOPHAGUS → transports food to crop. CROP → stores and softens feed.

PROVENTRICULUS (true stomach) → secretes digestive enzymes and acid.

GIZZARD (muscular stomach) → grinds feed mechanically (especially with grit).

SMALL INTESTINE (duodenum, jejunum, ileum) → main site of digestion and nutrient absorption.

CECA (2) → fermentation of fibre; some water reabsorption. LARGE INTESTINE / RECTUM →

water reabsorption.

CLOACA → common exit for digestive, urinary, and reproductive tracts.

VENT → external opening.

List 2 functions associated with the respiratory system in birds.

GAS EXCHANGE — oxygen is delivered to the blood and CO2 is removed. Birds have a highly efficient one-way airflow system using air sacs (not a simple in-out lung like mammals), allowing near-continuous oxygen extraction.

THERMOREGULATION — birds cannot sweat. They lose excess body heat through panting (evaporative cooling via the respiratory tract).

How are nutrients and waste moved around the body? Which organ is key? What happens when demand exceeds capacity?

MOVEMENT: Via the CIRCULATORY SYSTEM — blood carries oxygen, nutrients, hormones, and waste products to and from all tissues.

KEY ORGAN: The HEART pumps blood continuously; the lungs oxygenate it.

WHEN DEMAND EXCEEDS CAPACITY: In fast-growing broilers, the massive muscle mass demands more oxygen than the heart and lungs can supply. This leads to: ASCITES (right-side heart failure → fluid accumulates in the abdomen) and SUDDEN DEATH SYNDROME (SDS) — acute cardiac failure.

Can you label the parts of a hen's reproductive tract and give a major function for each?

OVARY → contains all follicles (potential yolks); only the left ovary is functional in birds. INFUNDIBULUM → catches the released yolk; site of fertilisation (if mating occurred). MAGNUM → secretes albumen (egg white) around the yolk (~3 hours). ISTHMUS → forms the shell membranes (~1.5 hours). UTERUS (shell gland) → deposits the calcium carbonate shell and shell pigment (~20 hours). VAGINA → holds the egg before laying; stores sperm in sperm storage tubules. CLOACA/VENT → egg is laid through here.

What does "photoperiodic" mean in terms of reproduction?

Photoperiodic means that reproduction is regulated by DAYLENGTH (the number of hours of light per day). In hens, increasing day length stimulates the hypothalamus → pituitary gland → ovaries to begin or increase egg production.

Commercial producers manipulate light programs to control when hens reach sexual maturity and to maintain consistent laying throughout the year. Pullets are reared under short or decreasing light to delay maturity, then "stimulated" with a sudden increase in light hours to trigger laying.

Beyond structural support and movement, what do bones provide to laying hens?

Bones serve as a CALCIUM RESERVOIR. Laying hens have a special type of bone called MEDULLARY BONE — a spongy calcium-rich bone tissue that forms inside the long bones (femur, tibia) under hormonal influence as hens approach sexual maturity.

This medullary bone is rapidly mobilised to supply calcium for eggshell formation when dietary calcium alone is insufficient. However, chronic over-reliance on bone calcium (when diet is inadequate) leads to osteoporosis and fractures — a major welfare issue in high-producing hens.