Here is the difference between a parent stock chicken and a layer breed, explained in points:

1. Purpose:
Parent Stock Chicken:
Raised for breeding purposes to produce offspring (fertile eggs) for commercial poultry farms.
Supplies chicks that can grow into either broilers (meat-producing) or layers (egg-producing).

Layer Breed:
Explicitly raised for egg production.
It is not used for breeding purposes but for laying table eggs consumed by humans.

2. Egg Production:
Parent Stock Chicken:
Produces fertile eggs that hatch into chicks for commercial farming.
The eggs are used for incubation, not for direct consumption.

Layer Breed:
Produces unfertilized eggs for human consumption.
Focused entirely on high egg-laying efficiency.

3. Genetic Focus:
Parent Stock Chicken:
Genetically selected for traits like growth rate, disease resistance, and fertility.
Maintains the genetic quality of future broilers or layers.

Layer Breed:
Genetically developed for consistent and high egg-laying performance.
Focused on egg quality, shell strength, and yolk color.

4. Lifecycle and Management:
Parent Stock Chicken:
Managed in a way that ensures maximum fertility and healthy offspring.
Requires strict breeding management and biosecurity measures.

Layer Breed:
Managed for continuous egg-laying cycles.
Focused on feed efficiency and maximizing egg production.

5. Economic Role:
Parent Stock Chicken:
Form the poultry industry's foundation by producing the next generation of commercial broilers or layers.

Layer Breed:
Provides a direct source of income by supplying eggs to the market for consumption.

6. Male and Female Birds:
Parent Stock Chicken:
Both males and females are raised for breeding purposes.

Layer Breed:
Primarily, female birds are raised as they lay eggs. Males are usually culled at an early stage.

7. Feeding Requirements:
Parent Stock Chicken:
Requires a specialized diet for reproductive performance and maintaining fertility.

Layer Breed:
Fed a diet rich in calcium and nutrients to ensure high egg production and strong eggshells.

8. Productivity Focus:
Parent Stock Chicken:
Focused on producing healthy chicks rather than eggs for consumption.

Layer Breed:
Focused on producing maximum eggs over its laying cycle.

These points clearly highlight the differences between parent-stock chickens and layer breeds in terms of their roles and management in poultry farming.