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Lecture 1

  • Line breeding vs. Inbreeding

    • Line Breeding: A form of selective breeding that aims to preserve desirable traits while minimizing the risk of genetic defects, usually involving breeding of relatives with a common ancestor.

    • Inbreeding: The mating of closely related individuals, which may increase the likelihood of genetic disorders but can also stabilize certain traits within a population.

      • Wild animals are more prone to inbreeding.

      • Dairy cow genetics (EX: Holstein) are far superior based on their miking abilities, which gives a lack of incentive to crossbreed.

  • Hybrid Vigor: improvement in environmental resilience and overall health seen in offspring as a result of crossbreeding different genetic lines.

    • Corn breeding

      • Double cross era: bred F1 (first allele cross) with F1, thereby creating F2 plants that exhibited enhanced traits such as yield stability and resistance to disease, ultimately contributing to a more robust agricultural system.

        • 0.8 bushel per year in advancement

      • Single cross era: planted more F1 crosses, which doubled hybrid vigor

        • F2 hybrid vigor was diminished by 50% compared to their predecessors

  • GMO Percentages:

    • Cotton - 96%

    • Sugar Beet - 95%

    • Soybean - 94%

    • Corn - 93%

    • Canola - 90%

    • Papaya - 50%

    • Alfalfa - 30%

    • Summer Squash - 12%

    • Sorghum does not utilize GMOs

  • Horizontal gene transfer is an issue in GMOs in meat animal production

  • The broiler industry is the most impressive in terms of progress

    • shortened growing times, increase in weights, lower mortality rate, and better feed efficiency

  • Genetics: the science of heredity

  • Animal breeding: the application of scientific knowledge to make genetic improvement in animals

    • “There are multipliers, and there are animal breeders.”

  • Selection: Which animals should be bred, and how many progenies should be generated?

  • Mating: Which combination will produce the best progenies?

  • Germ plasma: any sex gamete with a haploid number of chromosomes that can be used to propagate desired traits in future generations, ensuring genetic diversity and health in the animal population.

    • flows down

      • Seedstock → Commericial → Animal Products

      • Seedstock produces superior animal genetics

      • Commercial do not supply genetics to seedstock operators

      • Animal Products

  • The environment largely impacts fertility

    • The environment impacts 80% of fertility, and 20% is impacted by genetics

  • 50% of carcass weight can be attributed to factors such as feed quality, health management, and living conditions, and the other 50% is impacted by genetics

A wild population that arose from natural selection is more reproductively fit than any human-selected population.

The most important decision to make first is what breed you should be looking at, which is most advantageous for production goals. You’re then going to find individuals within the breed that meet your standards

Breeding Objective: a goal focused on the attainment of the most ideal traits for the breeding program or production system

Breeding Objective: selection of the most desirable animals for propagation of offspring that best target the breeding objective

  • P = G + E

  •     Phenotype = Genotype + Environment

    • P: an observable or quantifiable expression of a trait

    • G: the genetic makeup of an individual

    • E: heat/cold stress, food availability

Heritability: the proportion of variation that can be expected to be passed to the next generation (Darwinism-related traits)

  • LOW: 0-20%

  • MODERATE: 20-40%

    • growth traits (weight)

  • HIGH: >40%

    • carcass-related traits and height

  • ERT: economically relevant traits

    • Marbling Score

    • Annual Milk Yield - trait

      • World record in 78k lbs - phenotype

        • Avg is 26k lbs

    • Fat Content

      • Butterfat percent is the phenotype

    • EX: Color is the trait, red is the phenotype

  • Qualitative Trait (simply inherited): a categorical trait that can not be measured and is generally controlled by only one or a few genes

  • Genetic Progress

    • Generation Interval: the average. age of the parents when offspring are born, or the time required to replace a generation

      • The average age of the breeding females in a herd

        • The average is 5-6 years in cattle

    • Genetic Tools: technologies that can increase the contribution of genetics from a superior animal beyond the normal lifetime capacity

      • EX: superovulation, cloning

    • Single trait selection

      • EX: dairy cattle

        • Lower feed conversion

        • Subfertile

  • Mating Strategies

    • Crossbred animals tend to perform better than nonrelated purebreds; nonrelated purebreds tend to perform better than inbred purebreds

    • Any animal duplicated in a 3-generation pedigree is inbred

    • Outbred: no common ancestor in their pedigree

    • Outcrossing: mating of individuals within the same breed but that are not related

    • Linecrossing: the crossing of two different inbred lines

      • takes generations of planning

        • common in poultry and swine industries