Genetics, breeding and selection

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

breaking apart into two haploid cells with half the DNA

Mitosis

reults in a diploid with whole DNA

Eliete seedstock

(best of the best) that use lots of technology (AI and ET) to sell bull’s semen and females to the multiplier seed stock

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 enterprises

Growing and feeding enterprises

feed lots, no breeding, where finishing happens

Heritability

How likely a trait is to be passed on.

Repro has

lowest heritability (< 20%)

growth has

moderate heritability (20-39%)

Carcass has

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

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)

the higher the GI

the less improvement or change