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🐓Poultry Introduction - Nomenclature, Egg Grading, Terminology and Basic Concepts

Introduction to poultry farming covering scientific classification, chromosome number (2n=78), nomenclature (cock, hen, pullet, cockerel), egg grading, incubation period, and essential terminology for IBPS AFO and NABARD exams.

Nomenclature

  • Wild Chicken (Red Jungle Fowl): Gallus gallus
  • Domesticated Chicken: Gallus gallus domesticus
  • Chromosome number in chicken (2n): 78

The domesticated chicken (Gallus gallus domesticus) traces its ancestry to the Red Jungle Fowl (Gallus gallus), which was first domesticated in Southeast Asia thousands of years ago. Understanding the scientific classification and chromosome number is essential for studies in poultry genetics and breeding.

Terms for Chicken at Different Ages / Roles

TermDefinition
Cock / RoosterAdult male chicken
HenAdult female chicken (after laying first egg)
PulletYoung female before first egg (typically < 18–22 weeks)
CockerelYoung male under 1 year of age
ChickNewly hatched young chicken
CaponCastrated male, fattened for meat
BroilerMeat-type chicken, marketed at 6–8 weeks
LayerEgg-type hen kept for commercial egg production
Spent HenLayer at the end of her productive life (after ~72 weeks)

NOTE

Capon — Why are they produced? Castration (caponisation) removes the male hormones that cause toughness and aggression. Capons grow larger, deposit more fat (marbling), and develop softer, more flavourful meat than intact males — making them a premium meat bird.

TIP

Quick memory aid for terminology:

  • Age-based: Chick → Cockerel/Pullet → Cock/Hen
  • Purpose-based: Broiler (meat, 6–8 wk), Layer (eggs, 18–20 wk onwards), Capon (premium meat, castrated male), Spent Hen (retired layer)
Incubation period of chicken = 21 days

What is Poultry?

  • Rearing and breeding of domesticated fowls such as chicken, ducks, turkey and some varieties of pigeon for their meat and eggs. Poultry farming is one of the fastest-growing sectors of animal husbandry globally, driven by the increasing demand for affordable animal protein.
  • Word poultry related to Chicken, Duck, Turkey etc.

IMPORTANT

India’s Poultry — 20th Livestock Census 2019: Total poultry population = 851.81 million, making India the world’s 3rd largest poultry producer. Andhra Pradesh has the highest poultry population among all states. This figure includes backyard and commercial poultry across all species.


Poultry Sector

  • Indian poultry sector contribute 0.7% in National GDP and about 10% to the livestock GDP. India is one of the world’s largest producers of both eggs and poultry meat, with the industry experiencing rapid growth due to increasing urbanisation, rising incomes, and changing dietary preferences.
  • There are two types of birds 1. Layer 2. Broiler. Layers are raised primarily for egg production, while broilers are raised for meat production. Each type has been selectively bred for its specific purpose.

Layer

  • An egg laying female chicken up to one year after starting the laying of eggs. A layer is a commercial hen specifically bred and managed to produce the maximum number of eggs over her productive life.
  • Laying: The act of parturition in chickens. In poultry, the term laying refers to the process of an egg being formed in the oviduct and deposited by the hen.
  • Clutch: The number of eggs laid by a bird on consecutive days. A clutch of 3-4 eggs is preferred. A larger clutch size indicates better laying consistency and is a desirable trait in commercial layer breeds.
  • Broody: A hen which has stopped laying eggs temporarily. A broody hen exhibits the natural instinct to sit on and incubate eggs. In commercial operations, broodiness is undesirable as it halts egg production.

NOTE

Broodiness suppression in modern layers: Through selective breeding over decades, commercial layer strains (e.g., BV-300, Lohmann LSL) have had the broodiness instinct almost completely eliminated. This allows them to keep laying without interruption. Indigenous breeds retain stronger broodiness.

  • Laying period start: Commercial layers begin laying at 18–20 weeks of age. Peak production is typically achieved around 28–32 weeks.
  • Average egg laying throughout the year:

    • Indian hen: 60-80 eggs
    • Improved breed: 220-260 eggs

    The vast difference between indigenous and improved breeds highlights the importance of selective breeding and genetic improvement in poultry production.

  • Pause: It is the period between two clutches in which eggs are not laid by hen. The pause period is a natural resting phase in the laying cycle. Shorter pauses are desirable in commercial flocks.

  • Hen day production: This is arrived by dividing total number of eggs laid in the season by the average number of birds in the house. This metric accounts for daily flock size changes and provides a more accurate measure of current laying performance.

  • Hen housed average: This is arrived at by dividing the total number of eggs laid in the season by the number of birds originally placed in the house. No deductions are made for any losses from the flocks. This measure reflects overall flock performance including mortality, making it a stricter and more comprehensive metric.

  • World Egg production: 2nd globally (after China) as per BAHS 2024.

  • Egg Production: In 2023-24, the total egg production in the country is 142.77 billion eggs — ↑3.18% over 2022-23 (BAHS 2024).

  • Total five major egg producing States are Andhra Pradesh (17.85%), Tamil Nadu (15.64%), Telangana (12.88%), West Bengal (11.37%) and Karnataka (6.63%).


Egg

  • Egg is the physiological product of the female reproductive system. Each egg is a self-contained package of high-quality nutrients designed to support the complete development of a chick embryo.
  • Hen’s egg, apart from the ovum does contain other impotant nutrients for the growth and development of the embryo until hatching.
  • Average weight: 50-60 gm
  • Yolk: 30%
  • White or albumin: 58%
  • Inner & outer shell membranes and shell: 12%
Egg Structure — Internal Anatomy (Frequently Tested)

IMPORTANT

Albumen (egg white) has 4 layers (from yolk outward):

  1. Chalaziferous layer — dense, twisted; forms the chalaza
  2. Inner thick albumen — firm gel; largest fraction; most important for quality (measured by Haugh Unit)
  3. Inner thin albumen — liquid; adjacent to yolk
  4. Outer thin albumen — liquid layer just inside shell membranes

Exam tip: There are 4 albumen layers, not 3.

  • Chalaza: Two twisted protein (mucin) strands that anchor the yolk at the centre of the egg. Function: keeps the yolk suspended centrally so the embryo disc always faces upward toward the warmth source. Prominent chalazae = fresher egg.
  • Vitelline membrane: Thin transparent membrane that directly surrounds the yolk, separating it from the albumen.
  • Shell membranes: Two membranes (inner and outer) lie just inside the shell. They are separated at the broad end to form the air cell.
  • Air cell: Located at the broad end of the egg. It forms as the egg cools after laying due to contraction of contents. As the egg ages, moisture evaporates through the porous shell → air cell enlarges. Used in the float test for freshness: fresh egg sinks flat; stale egg stands upright or floats.
  • Shell composition: Approximately 94% calcium carbonate (CaCO₃), with small amounts of magnesium carbonate and calcium phosphate. The outermost coating is the cuticle (bloom) — a thin protein layer that seals shell pores to reduce bacterial entry and moisture loss.

TIP

Egg Freshness Tests:

  • Float test (specific gravity): Fresh egg sinks (high density); stale egg floats (air cell expanded, lower density). Simple field test.
  • Candling: Passing light through the egg to visualise internal contents — detects cracks, blood spots, meat spots, and air cell size. Used in grading.
  • Haugh Unit (HU): Log-based index of albumen height relative to egg weight. Higher HU = thicker albumen = fresher egg. Grade AA ≥ 72 HU; Grade A = 60–72 HU; Grade B < 60 HU.
  • Nutrient composition of egg weight
    • 12 % minerals
    • 12 % protein
    • 11% fat
    • 65 % water
    • Calories: 148 Cal/100 gm

Eggs are considered a complete food because they contain almost all the essential nutrients required by the human body, including all essential amino acids, making egg protein the reference standard for evaluating protein quality.


Grading of Eggs

Egg grading is the process of sorting eggs by size and quality. It ensures that consumers receive eggs of consistent weight and internal quality, and it helps producers fetch better market prices.

NOTE

Shell strength in grading is assessed by measuring the force (kg/cm²) required to crack the shell. It is influenced by dietary calcium and phosphorus levels, hen age (older hens lay thinner-shelled eggs), and breed. Poor shell strength leads to breakage losses — a major economic concern.


Broiler

  • These are young chicken (usually 9 to 12 weeks of age) of either sex, which are reared primarily for meat purposes and marketable age 6-8 weeks. Broiler chickens have been genetically selected for rapid growth and efficient feed conversion, reaching market weight in a remarkably short time.
  • Broiler has tender meat with soft pliable, smooth-textured skin and flexible breastbone cartilage.
  • Broiler chickens are breed and sold as White meat and Chicken Breast. White meat from the breast is particularly popular because it is lean, low in fat, and high in protein.
  • Sold for table purpose as they possess a very tender and delicious meat.
  • Dressing percentage in broiler poultry is 70-75%. Dressing percentage is the ratio of carcass weight to live weight, expressed as a percentage. A dressing percentage of 70-75% means that approximately three-quarters of the broiler’s live weight becomes usable meat.
  • They are the hybrid chicks having rapid growth and attaining about 1.5 - 2 kg weight during the period of 6 to 8 weeks of age. This remarkable growth rate is the result of decades of selective breeding combined with optimised nutrition and management practices.

IMPORTANT

Broiler vs Layer — Key Differences (MCQ-critical):

ParameterBroilerLayer
PurposeMeat productionEgg production
Market age6–8 weeks~72 weeks productive life
Body weight at market1.5–2 kg~1.8 kg (lighter frame)
FCR1.8–2.0 (feed:gain)Not the primary metric
Egg laying startNot applicable18–20 weeks
Annual eggsNot applicable220–260 (improved breeds)
Spent henNot applicableLayer past productive life

Composition of poultry meat

  • Water - 75%
  • Protein - 21%
  • Fat - 5-9%
  • Carbohydrates - small quantities

Poultry meat is considered one of the healthiest animal protein sources due to its high protein content, low fat percentage (especially in breast meat), and good balance of essential amino acids.


Incubation Parameters (Very Frequently Tested)

IMPORTANT

Artificial Incubation — Critical Parameters:

ParameterSetter (Day 1–18)Hatcher (Day 18–21)
Temperature37.5°C (99.5°F)37.2°C (99°F)
Relative Humidity55–60%65–70%
Egg turningMin. 3–4 times/dayStop on Day 18
  • Incubation period: 21 days (chicken) | 28 days (duck and turkey)
  • Natural incubation: A broody hen can cover approximately 10–12 eggs
  • Turning is stopped on Day 18 to allow the chick to position itself correctly for hatching (internal pipping begins)
  • Higher humidity in the last 3 days (hatch phase) prevents the shell membrane from drying and sticking to the chick

Economic Importance of Poultry

  • Cheapest animal protein: Eggs are the most affordable source of complete animal protein — critical for food security of rural and low-income populations.
  • Poultry manure: High nitrogen content (approximately 2.5–3% N on dry basis) makes it an excellent organic fertiliser. Also contains phosphorus and potassium.
  • Short generation interval: Poultry has the shortest generation interval (~6 months) of all livestock species, allowing the fastest genetic improvement through selective breeding.
  • Employment: Poultry farming provides significant employment to rural poor, with women playing a major role in backyard poultry — contributing to women’s economic empowerment.
  • Low capital, quick returns: Broilers reach market in just 6–8 weeks — far faster than cattle or pigs — making poultry the most capital-efficient livestock enterprise.

Key Poultry Research Institutions

InstitutionLocationKey Details
CARI (Central Avian Research Institute)Izatnagar, Bareilly, Uttar PradeshEstablished 1979; premier ICAR institute for poultry research
ICAR-DPR (Directorate of Poultry Research)Hyderabad, TelanganaDevelops synthetic breeds for egg and meat production

Broiler Industry — Key Statistics

  • India’s broiler meat production: ~4.8 million MT (2023-24)
  • India ranks among the top 5 globally in poultry meat production.

FCR — Feed Conversion Ratio

  • FCR = kg of feed required to produce 1 kg of body weight gain.
  • Broiler FCR: 1.5–1.8 (among the best in livestock).
  • Poultry has the lowest (best) FCR among all livestock species, making it the most feed-efficient source of animal protein.

Explore More 🔭

🟢 https://www.youtube.com/watch?v=KsuesiVJgtI

References & Sources


Summary Cheat Sheet

Concept / TopicKey Details
Wild chickenGallus gallus (Red Jungle Fowl)
Domesticated chickenGallus gallus domesticus
Chromosome number2n = 78
Poultry sector GDP0.7% of National GDP; 10% of livestock GDP
Cock / RoosterAdult male chicken
HenAdult female (after first egg)
PulletYoung female before first egg (< 18–22 weeks)
CockerelYoung male under 1 year
ChickNewly hatched young
CaponCastrated male, fattened for meat
LayerEgg-laying hen; up to 1 year after starting to lay
BroilerMeat chicken; reaches 1.5–2 kg in 6–8 weeks
Indian hen eggs/year60–80 eggs
Improved breed eggs/year220–260 eggs
India egg rank (world)2nd globally (after China) — BAHS 2024
Total egg production (2023-24)142.77 billion (↑ 3.18% over 2022-23) — BAHS 2024
Top egg-producing stateAndhra Pradesh (17.85%)
Top 5 egg-producing statesAP 17.85%, TN 15.64%, Telangana 12.88%, WB 11.37%, Karnataka 6.63%
ClutchEggs laid on consecutive days; 3–4 preferred
BroodyHen that stopped laying temporarily (incubation instinct)
Hen day productionTotal eggs ÷ average birds in house
Hen housed averageTotal eggs ÷ birds originally placed (includes mortality)
Egg average weight50–60 gm
Egg compositionYolk 30%, Albumin 58%, Shell 12%
Egg nutrientsProtein 12%, Fat 11%, Minerals 12%, Water 65%; 148 Cal/100 gm
Jumbo egg>70 gm
Broiler dressing %70–75%
Poultry meat compositionWater 75%, Protein 21%, Fat 5–9%
Incubation period (chicken)21 days
Incubation period (duck/turkey)28 days
Incubation temp37.5°C (99.5°F) — setter phase
Incubation humidity55–60% (setter) → 65–70% (hatcher, last 3 days)
Egg turningMin. 3–4×/day; stop on Day 18
Natural incubationBroody hen covers 10–12 eggs
Total poultry (20th LC 2019)851.81 million — world’s 3rd largest
Highest poultry stateAndhra Pradesh (also #1 in egg production)
Layer laying start18–20 weeks of age
Spent henLayer past productive life (~72 weeks)
Broiler FCR1.8–2.0 (feed kg per kg weight gain)
Egg shell composition~94% CaCO₃; outer coating = cuticle (bloom)
Albumen layers4: chalaziferous, inner thick, inner thin, outer thin
ChalazaTwisted protein strands anchoring yolk centrally
Air cellBroad end; enlarges with age — used in float test
Haugh Unit (HU)Albumen height index; higher = fresher (AA ≥ 72 HU)
CandlingLight-based method to detect cracks, blood spots, air cell
Broiler meat production~4.8 million MT (2023-24); India in top 5 globally
CARICentral Avian Research Institute, Izatnagar, Bareilly, UP — est. 1979
ICAR-DPRDirectorate of Poultry Research, Hyderabad — develops synthetic breeds
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