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7: Animal Breeding and Genetics

  • Page ID
    183107
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    • 7.1: Fundamentals of Genetics
      This page discusses the role of genetic principles in animal breeding to enhance production by altering traits of farm animals. It explains how an animal's genotype influences important characteristics like growth and disease resistance, thereby affecting market value. The genetic material, located in the nucleus and organized into chromosomes, is structured as DNA—composed of nucleotides.
    • 7.2: DNA Replication and Gene Expression
      This page covers the processes of DNA replication and gene expression. DNA replication ensures genetic continuity by unwinding the double helix and synthesizing complementary strands. Gene expression involves transcription, where mRNA is synthesized from DNA and processed, followed by translation, where ribosomes read mRNA to assemble amino acids into proteins based on the genetic code.
    • 7.3: Principles of Inheritance
      This page covers Gregor Mendel's foundational experiments with pea plants, establishing key genetic concepts such as genes, alleles, and homologous chromosomes. It explains the Principle of Segregation, which describes allele separation during gamete formation, and the Principle of Independent Assortment, indicating that allele segregation at one locus occurs independently of others. These principles are crucial for understanding genetic inheritance and animal breeding.
    • 7.4: Cell Division and Sex Determination
      This page discusses mitosis and meiosis, highlighting that mitosis produces two identical diploid cells for growth and maintenance, while meiosis yields four haploid gametes that enhance genetic diversity. It also explains sex determination in mammals, noting that females possess XX chromosomes and males have XY, with the male parent determining the offspring's sex through his contribution of either an X or a Y chromosome.
    • 7.5: Gene Expression Patterns
      This page covers inheritance patterns, highlighting dominant and recessive alleles, and explains expressions in homozygous recessive individuals. It distinguishes codominance and incomplete dominance, and discusses epistasis, multiple alleles, and testcross methods. Additionally, it explores sex-related inheritance, including sex-linked traits on X/Y chromosomes, sex-influenced traits influenced by hormones, and sex-limited traits specific to one sex.
    • 7.6: Population Genetics and Genetic Variation
      This page covers population genetics, emphasizing changes in gene and genotypic frequencies and their effect on genetic merit. It defines key concepts such as gene frequency and phenotypic frequency, while outlining four main forces driving these changes: mutation (introducing new alleles), genetic drift (random changes in small populations), migration (new alleles through breeding), and selection (natural and artificial influencing reproductive success).
    • 7.7: Quantitative Genetics and Heritability
      This page covers livestock trait classification into qualitative and quantitative types, with quantitative traits emphasized for economic significance. It outlines how phenotypes arise from genetic and environmental factors, detailing additive, dominance, and epistatic effects. Heritability is defined as the genetic contribution to phenotypic variation, affecting trait selection.
    • 7.8: Mating Systems
      This page explains inbreeding, which involves mating closely related individuals, potentially leading to inbreeding depression due to harmful recessive genes. It contrasts this with linebreeding, a milder method that focuses on desirable traits from a single ancestor while reducing genetic risks.
    • 7.9: Genetic Improvement Tools
      This page explores genetic evaluation methods in livestock breeding, highlighting Expected Progeny Differences (EPDs) for beef cattle and Predicted Transmitting Ability (PTA) for dairy cows. It explains EPDs' role in predicting progeny performance and the importance of accuracy in assessments. The Dairy Herd Improvement system enhances genetic evaluation, while swine advancements take advantage of rapid reproductive rates.
    • 7.10: Biotechnology and Genetic Engineering
      This page discusses marker-assisted selection (MAS) in breeding, highlighting the use of genetic markers, particularly single nucleotide polymorphisms (SNPs), to identify traits like disease resistance. It emphasizes the benefits of transgenic animals and gene editing technologies such as CRISPR, which provide precise genetic modifications and address ethical considerations, ultimately enhancing livestock breeding outcomes.
    • 7.11: CSI- Cow Scene Investigation — A Genetics Detective Game
      This page describes an interactive genetics detective activity where students work in groups to solve farm cases by selecting suitable sire designations based on specific goals like milk production or mastitis reduction. They gather evidence, shortlist bull candidates, and justify their choices, utilizing designations such as RobotPRO and GrazingPRO. The activity concludes with the students presenting detective reports and facing potential cross-examinations from peers and instructors.
    • 7.12: Summary and Flashcards
      This page discusses the evolution of animal breeding, highlighting the shift from traditional genetic selection to advanced biotechnology and genetic engineering. It emphasizes the benefits of these innovations, including predictable breeding outcomes, faster genetic enhancements, and the creation of transgenic animals.

    Animal breeding has shaped human civilization for thousands of years, transforming wild species into the diverse array of domesticated animals we depend on today. From the cattle that provide milk and meat to the chickens that supply eggs for breakfast tables worldwide, selective breeding has fundamentally altered the genetic makeup of animals to better serve human needs and preferences.

    At its core, animal breeding is both an art and a science. It combines careful observation, rigorous record-keeping, and increasingly sophisticated genetic tools to improve desirable traits in livestock, companion animals, and other species. Modern animal breeding enhances productivity, disease resistance, efficiency, and welfare while maintaining genetic diversity and adapting to changing environmental and market conditions.

    Piglets suckling

    Image credit: Mark Stebnicki from Pexels: https://www.pexels.com/photo/close-u...-cage-6792162/

    The fundamental principles that guide animal breeding programs include how traits are inherited from one generation to the next, how breeders identify superior animals for reproduction, and how today's breeding decisions shape the next generation. We'll explore traditional methods refined over centuries and cutting-edge genomic technologies revolutionizing the field.

    The stakes of these breeding decisions extend far beyond individuals. Modern animal breeders must balance food security, economic sustainability, animal welfare, and environmental conservation as global population growth drives increased demand for animal products and climate change presents unprecedented challenges. Strategic, scientifically-informed breeding has never been more critical to meeting these complex, interconnected needs.

    • 7.1: Fundamentals of Genetics
      This page discusses the role of genetic principles in animal breeding to enhance production by altering traits of farm animals. It explains how an animal's genotype influences important characteristics like growth and disease resistance, thereby affecting market value. The genetic material, located in the nucleus and organized into chromosomes, is structured as DNA—composed of nucleotides.
    • 7.2: DNA Replication and Gene Expression
      This page covers the processes of DNA replication and gene expression. DNA replication ensures genetic continuity by unwinding the double helix and synthesizing complementary strands. Gene expression involves transcription, where mRNA is synthesized from DNA and processed, followed by translation, where ribosomes read mRNA to assemble amino acids into proteins based on the genetic code.
    • 7.3: Principles of Inheritance
      This page covers Gregor Mendel's foundational experiments with pea plants, establishing key genetic concepts such as genes, alleles, and homologous chromosomes. It explains the Principle of Segregation, which describes allele separation during gamete formation, and the Principle of Independent Assortment, indicating that allele segregation at one locus occurs independently of others. These principles are crucial for understanding genetic inheritance and animal breeding.
    • 7.4: Cell Division and Sex Determination
      This page discusses mitosis and meiosis, highlighting that mitosis produces two identical diploid cells for growth and maintenance, while meiosis yields four haploid gametes that enhance genetic diversity. It also explains sex determination in mammals, noting that females possess XX chromosomes and males have XY, with the male parent determining the offspring's sex through his contribution of either an X or a Y chromosome.
    • 7.5: Gene Expression Patterns
      This page covers inheritance patterns, highlighting dominant and recessive alleles, and explains expressions in homozygous recessive individuals. It distinguishes codominance and incomplete dominance, and discusses epistasis, multiple alleles, and testcross methods. Additionally, it explores sex-related inheritance, including sex-linked traits on X/Y chromosomes, sex-influenced traits influenced by hormones, and sex-limited traits specific to one sex.
    • 7.6: Population Genetics and Genetic Variation
      This page covers population genetics, emphasizing changes in gene and genotypic frequencies and their effect on genetic merit. It defines key concepts such as gene frequency and phenotypic frequency, while outlining four main forces driving these changes: mutation (introducing new alleles), genetic drift (random changes in small populations), migration (new alleles through breeding), and selection (natural and artificial influencing reproductive success).
    • 7.7: Quantitative Genetics and Heritability
      This page covers livestock trait classification into qualitative and quantitative types, with quantitative traits emphasized for economic significance. It outlines how phenotypes arise from genetic and environmental factors, detailing additive, dominance, and epistatic effects. Heritability is defined as the genetic contribution to phenotypic variation, affecting trait selection.
    • 7.8: Mating Systems
      This page explains inbreeding, which involves mating closely related individuals, potentially leading to inbreeding depression due to harmful recessive genes. It contrasts this with linebreeding, a milder method that focuses on desirable traits from a single ancestor while reducing genetic risks.
    • 7.9: Genetic Improvement Tools
      This page explores genetic evaluation methods in livestock breeding, highlighting Expected Progeny Differences (EPDs) for beef cattle and Predicted Transmitting Ability (PTA) for dairy cows. It explains EPDs' role in predicting progeny performance and the importance of accuracy in assessments. The Dairy Herd Improvement system enhances genetic evaluation, while swine advancements take advantage of rapid reproductive rates.
    • 7.10: Biotechnology and Genetic Engineering
      This page discusses marker-assisted selection (MAS) in breeding, highlighting the use of genetic markers, particularly single nucleotide polymorphisms (SNPs), to identify traits like disease resistance. It emphasizes the benefits of transgenic animals and gene editing technologies such as CRISPR, which provide precise genetic modifications and address ethical considerations, ultimately enhancing livestock breeding outcomes.
    • 7.11: CSI- Cow Scene Investigation — A Genetics Detective Game
      This page describes an interactive genetics detective activity where students work in groups to solve farm cases by selecting suitable sire designations based on specific goals like milk production or mastitis reduction. They gather evidence, shortlist bull candidates, and justify their choices, utilizing designations such as RobotPRO and GrazingPRO. The activity concludes with the students presenting detective reports and facing potential cross-examinations from peers and instructors.
    • 7.12: Summary and Flashcards
      This page discusses the evolution of animal breeding, highlighting the shift from traditional genetic selection to advanced biotechnology and genetic engineering. It emphasizes the benefits of these innovations, including predictable breeding outcomes, faster genetic enhancements, and the creation of transgenic animals.


    7: Animal Breeding and Genetics is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by LibreTexts.