Question:
Closed nucleus breeding system has
Closed nucleus breeding system has
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Closed nucleus systems are commonly used in commercial pig and poultry breeding to maintain strict biosecurity and protect elite genetic lines from external pathogens.
Updated On: Aug 5, 2026
- four way flow of genes
- three way flow of genes
- two way flow of genes
- one way flow of genes
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The Correct Option is D
Solution and Explanation
Step 1: Understanding the Concept:
Nucleus breeding systems are hierarchical structures designed to spread genetic improvement from a selected group of animals down to the wider commercial population.
These systems are classified as either open or closed based on whether they accept outside genetic material into the top tier.
Step 2: Detailed Explanation:
A closed nucleus breeding scheme is organized into a pyramid structure with three main tiers:
The Nucleus: The top tier, which contains a relatively small group of animals under intense selection. All genetic evaluations and selections are made here.
The Multiplier: The middle tier, which receives superior genetic material from the nucleus to multiply the numbers of improved animals.
The Commercial Herd: The bottom tier, which uses the males or semen produced by the multipliers to produce commercial animals.
In a closed nucleus system, no outside genetic material is introduced into the nucleus once it is established.
All replacement males and females for the nucleus are selected from within the nucleus itself.
As a result, genes flow in a single direction: from the nucleus down to the multiplier, and then to the commercial herds.
This one-way flow of genes prevents the introduction of outside diseases and allows for tight control over the genetic direction of the program, though it can increase the rate of inbreeding if not carefully managed.
In contrast, open nucleus systems allow superior females from lower tiers to be selected and brought up into the nucleus, creating a two-way flow of genes.
Step 3: Final Answer:
Therefore, a closed nucleus breeding system is characterized by a one-way flow of genes.
Nucleus breeding systems are hierarchical structures designed to spread genetic improvement from a selected group of animals down to the wider commercial population.
These systems are classified as either open or closed based on whether they accept outside genetic material into the top tier.
Step 2: Detailed Explanation:
A closed nucleus breeding scheme is organized into a pyramid structure with three main tiers:
The Nucleus: The top tier, which contains a relatively small group of animals under intense selection. All genetic evaluations and selections are made here.
The Multiplier: The middle tier, which receives superior genetic material from the nucleus to multiply the numbers of improved animals.
The Commercial Herd: The bottom tier, which uses the males or semen produced by the multipliers to produce commercial animals.
In a closed nucleus system, no outside genetic material is introduced into the nucleus once it is established.
All replacement males and females for the nucleus are selected from within the nucleus itself.
As a result, genes flow in a single direction: from the nucleus down to the multiplier, and then to the commercial herds.
This one-way flow of genes prevents the introduction of outside diseases and allows for tight control over the genetic direction of the program, though it can increase the rate of inbreeding if not carefully managed.
In contrast, open nucleus systems allow superior females from lower tiers to be selected and brought up into the nucleus, creating a two-way flow of genes.
Step 3: Final Answer:
Therefore, a closed nucleus breeding system is characterized by a one-way flow of genes.
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