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Questions and Answers
What symbol represents the rose comb allele?
What is the mating system called where a few males run with an entire flock of females?
Which mating system tends to result in lower fertility due to the male's lack of competition?
What are sex-linked genes?
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What is the practice of replacing older males with younger ones to increase fertility called?
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What ratio of males to females is typical in flock mating for heavier breeds?
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Which term describes the arrangement where females are mated to individual males kept in cages?
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Which company type is responsible for providing eggs to hatcherymen?
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What is the primary goal of poultry breeding?
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Which trait is NOT identified as contributing to an increase in net returns for producers?
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What do sex cells contribute to when fertilization occurs?
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What is the primary role of DNA in genetics?
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Which term describes the observable traits expressed by an individual's genotype?
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Which term refers to a pair of genes at the same locus that code for different characteristics?
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In poultry genetics, what characteristic is described as masking the expression of a paired allele?
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Which of the following statements is true about chromosomes in male and female chickens?
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Which condition allows for selective breeding to be efficient in poultry?
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How long is the incubation period for chicken eggs?
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Which of the following characteristics is associated specifically with broilers?
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What is a locus in genetics?
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Which type of dominance results in a blending of traits in the phenotype?
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What unique advantage do chickens have in breeding?
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Study Notes
Poultry Breeding
- Breeding uses principles of applied genetics to develop strains or breeds for optimized meat and egg production.
- Key traits for economic benefit in poultry include fertility, hatchability, growth rate, egg production, and feed conversion (efficiency).
- The poultry industry is experiencing annual growth of approximately 5% due to continuous genetic improvements and management practices.
- Main interests for animal breeders are maximizing product output per bird, improving production efficiency, and enhancing product quality (eggs and meat).
Poultry Breeding: Key Traits
- Hens: Desired traits include large numbers of large and extra-large eggs, low rearing and laying mortality, optimal body weight, high albumen quality, efficient feed conversion, good hatchability, and strong shell thickness.
- Broilers and Turkeys: Key traits include fast growth rate, desirable body conformation, high feed conversion ratio, absence of leg weakness, and resistance to diseases.
Genetics: The Foundation
- Genetics focuses on the study of inheritance.
- Cells are the basis of all living material.
- Somatic cells constitute all body tissues, while sex cells facilitate species continuation.
Cell Structure and Function
- Cell membrane: Acts as a barrier, preventing mixing with other cells' contents.
- Cytoplasm: Located between the nucleus and cell membrane.
- Nucleus: Contains genetic material and facilitates its transmission.
Chromosomes: Carriers of Genetic Information
- Rod-shaped structures residing within the nucleus.
- Each chromosome contains identical genetic information and exists in pairs during mitosis.
- During fertilization, half of the genetic information comes from the sperm and the other half from the egg, contributing to the embryo's genetic makeup.
Types of Chromosomes
- Autosomes: All chromosomes in the body except for one pair.
- Sex chromosomes: Determine the sex of an individual.
Genes: Units of Heredity
- Located within chromosomes, genes determine specific characteristics that differentiate body parts and species.
- Located at identical locations on each pair of chromosomes.
Deoxyribonucleic Acid (DNA): The Molecular Makeup
- DNA is the primary genetic material found in cell nuclei.
- Composed of repeating units of four nucleotide bases: Guanine (G), Cytosine (C), Thymine (T), and Adenine (A), all associated with phosphoric acid and a sugar.
DNA Molecule: The Code for Life
- Nucleotide bases exist in sequences of three, forming a codon.
- Base sequences serve as a code to transfer genetic information during cell division.
- Each sequence represents a specific amino acid.
The Role of DNA: From Code to Function
- DNA code is translated by cells to create proteins and enzymes, determining their function.
- Influences cell differentiation and development.
- Dictates the outcome of the embryo.
Sex Determination in Chickens
- Male chickens: 38 pairs of autosomes + 1 pair of complete sex chromosomes (ZZ) = 39 pairs.
- Female chickens: 38 pairs of autosomes + 1 complete sex chromosome (Z) + 1 incomplete sex chromosome (W).
- Sex chromosomes in females (ZW), males (ZZ).
- Females are the heterogametic sex (different sex chromosomes), while males are homogametic (identical sex chromosomes).
- Females determine the sex of the offspring.
Genotype and Phenotype: Genetic Makeup vs Observable Traits
- Genotype: The actual traits coded in paired genes (alleles) at the same locus on paired chromosomes.
- Phenotype: The observable expression of the traits coded in paired genes at the same locus on paired chromosomes.
Understanding Dominance and Incomplete Dominance
- Complete Dominance: One paired allele completely masks the expression of the other.
- Incomplete Dominance: Both paired alleles are partially expressed, resulting in a blended trait in the phenotype.
Essential Genetic Concepts: Homozygous and Heterozygous
- Homozygous: Paired genes (alleles) at the same locus on paired chromosomes code for the same characteristics (traits).
- Heterozygous: Similar to homozygous, but the paired alleles code for different characteristics.
Key Examples: Rose Comb and Barred Feather Pattern
- Rose comb (R) is dominant to single comb (r).
- Barred (B) is completely dominant to non-barred (b).
The Foundation Breeders: Key Players in Poultry Breeding
- Companies like Ross, Arbor Acres, and Hubbard are specialized breeding enterprises.
- They operate as Foundation Breeders, providing eggs to hatcherymen (Multipliers) under contracts.
- Multipliers hatch the eggs and send chicks to grow-out farms.
Mating Systems in Poultry: Optimizing Reproduction
- Flock Mating: A few males run with a flock of females, with the male-to-female ratio depending on breed size.
- Pen Mating: A pen of females is mated with a single male; fertility is lower than flock mating due to lack of male competition.
- Stud Mating: Females are mated with individual males kept in cages; labor-intensive, birds are mated weekly, reserved for valuable males.
- Artificial Insemination: A method of mating discussed in a separate lab session.
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Description
Explore the principles of poultry breeding focused on optimizing meat and egg production. Learn about the key traits that enhance fertility, growth rates, and overall production efficiency in hens, broilers, and turkeys. This quiz will deepen your understanding of how genetics play a vital role in the poultry industry.
