breeding values and expected progeny differences

Question 1

what is a breeding value

Answer 1

-the number that represents the value as a parent
-the deviation of the animals progeny compared to the average reference population

Question 2

what does the breeding value depend on

Answer 2

-the average performance of the reference population
-the value of the alleles that each progenitor can transfer to its progeny

Question 3

what makes up the G in P=G+E

Answer 3

A(additive effect, breeding value)+D(dominance deviation)+I(gene interactions)

Question 4

what is an animals breeding value directly proportional to

Answer 4

how many favourable alleles it carries AND transmits to offspring

Question 5

genotypic values (V)

Answer 5

-two alleles, A1 and A2
-three genotypes:
-A1A1
-A1A2
-A2A2

Question 6

how to alter phenotype

Answer 6

-impact environment
-change genotype

Question 7

V

Answer 7

genotypic value (half the breeding value)

Question 8

A

Answer 8

breeding value (additive genetic component

Question 9

what happens if the A=0 or less

Answer 9

no improvement to the herd

Question 10

how should the genotypic values of bulls be calculated based on

Answer 10

breeding bulls to a wide varity of cows, ideally in a wide variety of herds in many environments
dairy bull EPD scored require milk records form 50 daughters from several herds

Question 11

what is the breeding value in relation to the average deviation

Answer 11

twice the average deviation of the animals offspring form mean

Question 12

BV (A)= (equation)

Answer 12

2 x progeny difference

Question 13

what is the breeding value a measure of

Answer 13

-the animals expected progeny perfromance relative to the population mean
-twice the average deveation of the animals offspring from the mean
-twice because only 1/2 is being measured form one parent

Question 14

what is breeding value affected by

Answer 14

-gene frequency
-types of gene action (dom, codom)
-difference in genotypic value between the homozygotes
ie its not constant, gene frequency can only be altered through selection
-its not possible to determince an animals true breeding value but can estimate it. = estimated breeding value

Question 15

things you need for calculations of EPDs

Answer 15

-animals own performance (important with highly heritable traits)
-pedigree
(sire and maternal grandsire (min), imprtant with traits of low heritability, used for young animals with young progeny
-progeny records
(important with traits of low heritability, important with traits that cant be measure in the individual)

Question 16

what are EPDs derived from

Answer 16

-complex calculations to estimate the animals genetic worth as a parent
-they factor in many variables yp estimate only the genetic porportion that contributes towards the trait in the offspring

Question 17

what is estimated breeding value

Answer 17

-genetic worth of an animal

Question 18

how do you calculate estimated breeding value

Answer 18

-heritability x (individual - test average)

Question 19

EPV vs EPD

Answer 19

-bull transmits 1/2 of his breeding value to his offspring dam transmits other half
-EPD is 1/2 of EBV

Question 20

what does national (international) cattle evaluation by breed account for

Answer 20

-accounts for all pedigree relationships (parent, sib)
-accounts for herd location differences
-accounts for management differences
-accounts for relationships between traits

Question 21

how often does nat (inter) cattle evaluations by breed recalculate EPDs

Answer 21

weekly, monthly, annually

Question 22

what are some growth EPDs

Answer 22

birth weight, wean weight, yearling weight

Question 23

what is accuracy for EPDs

Answer 23

-measure of reliability
-indicator of risk
-increase as more information is used to calculate EPD

Question 24

combining molecular genomics with EPD

Answer 24

-predicts what it will be like based on genomics with out seeing results
-molecular genomics SNP chips
-it claims to improve accuracy in young sires

Question 25

what does SNP stand for

Answer 25

single nucleotide polymorphism