Breeding

Heritability estimates (h2)

- portion of the total

phenotypic variation that is due to heredity

moderately to highly

Production traits are ____ heritable

lowly

Reproductive traits are ___ heritable

Repeatability estimates (R)

- refer to expression of the same trait at different stages of life of the

same individual

REPRODUCTION

–Includes both physical and physiological processes from fertilization to

development of young

Mechanics of Inheritance

The biological processes and pathways—specifically reproduction, gametogenesis, and fertilization—through which genetic materials flow and pass down from parents to offspring.

• GAMETOGENESIS

• FERTILIZATION

Two Processes involved in Flow of Genetic Materials

GAMETOGENESIS

The biological process of creating sex cells, which is divided specifically into spermatogenesis (male) and oogenesis (female).

FERTILIZATION

The union of male and female sex cells that restores the full diploid number of chromosomes in the resulting organism.

BREEDING

application of animal genetic principles to improve animal performance;

SELECTION

-certain animals are preferred for the production of the next generation

NATURAL SELECTION

survival of the fittest

ARTIFICIAL SELECTION

with human intervention to improve existing breeds and strains

-TANDEM

-INDEPENDENT CULLING

-SELECTION INDEX

SELECTION METHODS USED:

TANDEM

genetic progress is aimed over a group of 2 or 3 traits one at a time

INDEPENDENT CULLING

each trait should meet a certain standard set for the purpose, if 1 trait among 3

traits does not meet the std. then animal is rejected

SELECTION INDEX

most applicable when selecting for more than 1 quantitative trait simultaneously with their corresponding importance or weights

• INDIVIDUALITY

• PEDIGREE

• PROGENY TEST

• COLLATERAL RELATIVES

• SPECIFIC COMBINING ABILITIES

SELECTION FOR SUPERIOR STOCKS

INDIVIDUALITY-

selection is based on phenotype for a particular trait

PEDIGREE

selection is based on record of individual’s ancestors “pedigree clean” – without history of bad genes

PROGENY TEST

selection is based on animals are rejected or accepted depending on the performance of their progenies when subjected to a standard test

COLLATERAL RELATIVES

selection is based on performance of distant relatives (aunts, uncles, half-brothers, half sisters

SPECIFIC COMBINING ABILITIES

selection is based on if some traits that an animal possess can combine well (nicking ability) with other traits (genes affect expression of other genes) and the effect of environment

Mating Schemes

Structured breeding systems designed to manage genetic combinations, such as using inbreeding to achieve specific genetic goals in a population.

Inbreeding

The production of offspring by parents who are more closely related by descent than the average of their original population.

Inbreeding Depression

The biological opposite of hybrid vigor, marked by a reduction in performance, vigor, or fertility due to the breeding of closely related individuals.

Increased Homozygosity

A primary result of inbreeding that brings existing recessive genes together (without increasing the overall number of recessive genes), fixing specific traits in an inbred line.

: Phenotypic Uniformity

An increase in physical and measurable consistency across an inbred population when selection is combined with increased homozygosity.

LINE BREEDING

-MILD FORM OF INBREEDING TO CONCENTRATE THE INHERITANCE OF ONE ANCESTOR (USUALLY MALE) OR ONE LINE OF ANCESTORS IN THE LINE BRED INDIVIDUALS

CROSSBREEDING

-MATING OF 2 OR MORE UNRELATED DIFFERENT BREEDS (INCREASE HETEROZYGOSITY OF GENES)

HETEROSIS OR HYBRID VIGOR IS ACHIEVED

- IMPROVED PERFORMANCE OF CROSSBREDS OVER THE PARENTS

Crossbreeding

Two-way cross – mating of two different breeds of pigs

Three- way cross – mating of three different breeds of pigs

Four-way cross or hybridization

– mating of four different breeds of pigs

OUTCROSSING (PUREBREEDING)

-MATING OF UNRELATED ANIMALS WITHIN THE SAME BREED

UPGRADING OR GRADING–UP

-IMPROVE BLOODLINE OF NATIVE BREED

Artificial Insemination

- still considered the most useful and applicable strategy of increasing the genetically superior genes from proven sires and dam, - where collected semen is (quality, fresh or frozen) deposited to female reproductive system through catheter (AI gun)

Genetic engineering or recombinant DNA technology –

techniques to construct new combinations of DNA molecules that do not exist naturally

Splitting of DNA

–split chemically by enzymes

Splicing

– isolation of gene fragment from one organism

Recombinant DNA

– new hybrid molecule called recombinant DNA inserted into an organism ( change in the organism’s physical traits)

Gene cloning

– specific genes to produce specific products

Gene library

– collection of plasmids representing entire genomic DNA

Gene therapy

– introduction or transferring of gene (normal copy of defective gene) causing certain defect to an individual

DNA fingerprinting

– Exam of individual genetic blueprint- its own DNA

Gene splicing

– plucking of gene for a specific trait from one organism, transplant to another