Genetics, breeding and selection

What are the parts of a chromosome?

What are the parts of a chromosome: Genes → chromosomes → alleles

alleles: different versions at a specific locus

homozygous: two of the same alleles (AA or aa)

heterozygous: two different alleles (Aa)

Meiosis and mitosis

Meiosis: breaking apart into two haploid cells with half the DNA

Mitosis: reults in a diploid with whole DNA

Structure of the breeding industry:

Top: Eleite seedstock (best of the best) that use lots of technology (AI and ET) sells bulls semen and females to the multiplier seedstock

Multiplier seedstock: multiplying genetics from the eleite (AI and ET), sells bulls, females, and semen to commercial producers

Commercial producers (i.e. cow calf) sell offspring to growing and feeding enerprises

Growing and feeding enterprises: feed lots, no breeding, where finishing happens

Influences on genetic variation

Heritability: How likely a trait is to be passed on.

Repro: lowest heritability (< 20%)

growth: moderate heritability (20-39%)

Carcass: highest heritability (> 40%)

Phenotype will: only change depending on how heritable the traits are

Selection differential or reach: superiority or inferiority compared to the average

Generation interval: Average age of parents when offspring are born; the higher the GI, the less improvement or change

Selection

Tandem selection: Selecting for one trait at a time

Independent culling level: (est. a baseline for multiple traits), minimum culling for traits

Selection index: multiple traits each having value added (EPD)