Hatching Eggs and Hatchery Management Study Guide

Intended Learning Outcomes and the Breeding Pyramid

The description of hatchery management.
Identification of key performance parameters within a hatchery.
Listing optimal performance targets for hatching operations.
The Breeding Pyramid Structure: Grandparent lines lead to the pure breed stock.

The Five Stages of Egg Formation in the Reproductive Tract

The process begins with light stimulation via the pineal gland, which triggers the release of Follicle Stimulating Hormone (FSH).
Follicles are produced in the ovary, and each follicle contains a yolk.
Stage 1: Infundibulum. This is the first stage where the yolk is captured and where fertilization takes place.
Stage 2: Magnum. This stage involves the deposition of albumin (egg white). There are four distinct layers of albumin deposited at this point.
Stage 3: Ismac. In this stage, the synthesis of the egg membrane occurs.
Stage 4: Uterus. This is the site for the deposition of the eggshell.
Stage 5: Vagina. The role of the vagina is strictly to release the egg; no deposition of any materials occurs here.

Questions & Discussion: Fertilization and Anatomy

Question: Where does fertilization take place in the reproductive system of a bird? Response: It takes place in the infundibulum.
Discussion on mating: A single hen may be mounted by multiple males. While mammals do not store sperm in this manner, the speaker noted the need to check specific details regarding avian sperm storage and will return with more information.

Egg Anatomy and Shell Integrity

The eggshell contains pores which serve a critical biological purpose.
Pores allow for embryo respiratory exchange: Oxygen enters the shell, and carbon dioxide is expelled.
Importance of integrity: If the shell integrity is compromised or if the egg is dirty, bacteria can enter through these pores.
Management Warning: Poultry handlers should never clean eggs with a cloth. Cleaning eggs manually can compromise the shell or push dirt further into the pores.
Selection Process: Dirty eggs should be selected out and excluded from the hatchery to avoid contamination risks.

Nest Box Management and Hygiene

Eggs naturally come out clean from the hen; they do not emerge with fecal matter.
Eggs become dirty primarily when they fall on the floor or if the environment is poorly maintained.
Hens do not naturally poop on their eggs. If fecal contamination occurs on eggs, it indicates a management failure ( $e.g.$ , not providing enough egg boxes or insufficient surface area for the chickens).
If egg boxes are insufficient, chickens will lay eggs on the floor, where they are more likely to be stepped on or soiled.

Hatchery Procedures: Disinfection and Storage

The first step in the hatchery is disinfection. Received eggs are sorted to remove dirty specimens and then disinfected.
Formaldehyde Disinfection: * Commonly used in the UK because it is a gas and does not cause the eggs to become wet. * It is currently being banned because it is carcinogenic to humans.
Alternative Disinfectants: Hydrogen peroxide, quaternary ammonium compounds (QAC), or chlorine. * Problem with alternatives: These are wet/liquid disinfectants. They may stick to shells or impact the cuticle, which can negatively affect hatchability.
Criteria for Good Disinfectants: It should not impact the cuticle, bacterial counts after treatment should be low, and it must not reduce hatchability.
Egg Storage Rules: * Eggs should ideally be taken to the hatchery on the same day they are laid. * Eggs can be kept for up to $7\,\text{days}$ . * Consequence of storage: Keeping eggs longer than $7\,\text{days}$ causes hatchability to decrease by approximately 1\,\text{%} to 1.5\,\text{%}.

Principles of Incubation and Hatchery Machinery

Hatcheries provide a controlled environment for the optimal incubation of a large volume of eggs ( $e.g.$ , $100,000$ breeders produce far more eggs than a hen can sit on managed naturally).
The Two Types of Machines in a Hatchery: 1. Incubator (also known as a "Setter"): Eggs stay here for the first $18\,\text{days}$ . 2. Hatcher: Eggs are moved here for the final $3\,\text{days}$ .
Total Incubation Period for Chickens: $21\,\text{days}$ .

Egg Selection Criteria

Size selection: Proper sized eggs must be chosen. Very small or very large eggs are avoided.
Small eggs: Often infertile or produce non-viable chicks that are too small.
Large/Double-Yolked eggs: These should be removed because two embryos will compete for nutrients and space, resulting in poor outcomes.
Cracked and dirty eggs: These are excluded to prevent "explosions."
The Explosion Phenomenon: Bacteria enter cracked or dirty eggs. Inside the warm incubator, the bacteria produce gas. The pressure builds until the egg explodes, messing up other eggs and ruining widespread hatchability.
Signs of Unsuitable Eggs: Improper rounded shape, presence of blood stains (which can indicate disease like TB or act as a medium for bacteria), or coming from a sick parent flock.

Environmental Control: Temperature and Pre-Warming

Temperature Transitions: * Hen's body temperature: $41\,^{\circ}C$ . * Egg storage/Room temperature: $21\,^{\circ}C$ . * Incubator temperature: $37.5\,^{\circ}C$ to $37.8\,^{\circ}C$ .
Pre-warming: Before placing eggs into the incubator at $37.5\,^{\circ}C$ , they must be pre-warmed to prevent "shock."
Incubator Management: The incubator should be set at the target temperature before eggs are added. Gradually increasing the temperature while eggs are inside slows embryo development and hurts hatchability.
Core parameters to monitor: Temperature, humidity, ventilation, and microbial factors.

Incubation Mechanics: Turning and Candling

Turning: In the incubator, eggs are turned to mimic the natural behavior of a hen. This is essential for proper embryo development.
Candling: Provides information on whether an egg is fertilized. * Schedule: Performed at Day $6$ or $7$ , Day $10$ , and at the point of transfer to the hatcher. * Benefits: Helps improve farm performance by identifying fertility issues and maximizes incubator space by removing non-viable eggs.
Transfer: At Day $18$ , eggs move to the hatcher.
The Hatcher Environment: Unlike the incubator, the hatcher does not perform turning. The eggs sit on shelves until they hatch.

Post-Hatch Processing and Quality Control

Vaccination Methods: * In-ovo vaccination: Automated puncture of the shell at the hatcher stage; the hole is sealed with a protective substance. * Spray vaccination: Used for respiratory diseases like Newcastle Disease and Infectious Bronchitis (IB). * Subcutaneous injection: Used for vector diseases like Marek's Disease and Infectious Bursal Disease (IBD).
Chick Grading and Sexing: * Target Hatchability: 95\,\text{%} to 97\,\text{%}. * Manual and automated grading is performed.
Sexing Techniques: * Feather Sexing: Look at the top wing coverts. In males, these feathers will be longer and sharper/whiter than the ones underneath. In females, they are shorter. * Vent Sexing: Visual inspection of the bird's vent.
Characteristics of a Healthy Chick: * Active, alert, and red/healthy in appearance. * Uniformity in age and size. * Clean beaks and fluffy yellow down (not pale). * Yolk Sac Absorption: The yolk sac must be fully absorbed. If not, it becomes a source of infection and the chick will fail to take in feed properly. * Clean Vents: Avoid "pasty vent" (sticky fecal matter). If the vent is sticky, the chick cannot defecate once it begins eating in the grower house.

Hatchery Biosecurity and Traffic Flow

Transportation: Chicks must be moved under monitored temperature, humidity, and ventilation.
Traffic Flow: Movement in a hatchery must be "unidirectional" (one-way flow).
Protocol: Personnel and materials enter at egg reception and move through storage, incubation, hatching, and processing without backtracking.
Biosecurity Importance: Prevents cross-contamination, such as moving bacteria from incoming egg trucks back into the clean area where chicks are being processed and vaccinated.