Selection technique

Question 1

selection of breeding stock: who

Answer 1

-individual
-relative
-ancestors (pedigree)
-sib
-progeny

Question 2

selection of breeding stock: how

Answer 2

-independent culling levels
-tandem selection
-index of weighted traits

Question 3

independent culling levels

Answer 3

-select for minimun value per characteristic
-e.g. every breeding animal>minimum for every trait in the goal set, no average
-R.O.P bulls (rec of preformance)
-30 cm scrotal circumference
-“pass” on feet and legs
-> average weight grain for breed

-useful for multi purpose animal
-potentially cull many animals

Question 4

tandem selection

Answer 4

-select for most important trait this season, 2nd trait next season, ect
-i.e. sequential selection of traits, not simultaneous
-efficient if all desired traits are positively correlated
-in reality- used primarily as a temportary slection to focus on the most important trait
-i.e: egg size; ignoring number, colour, shape of eggs

Question 5

index selection

Answer 5

-uses a formula to simultaneously select for several traits, emphasizing some more then others
-boar selection index:
-economic indexes
feed to gain
lean yield
loin depth
growth rate

Question 6

indirect selection

Answer 6

-use of a correlated trait (B) to select for another trait (A)
-useful for:
-traits that are difficult to measure e.g milk yield: fat yield r=.80
-traits with low h2 but high r e.g h2 of longevity in holsteins= 0.04 longevity : 1st lactation milk yield r=.60

Question 7

indirect selection for horsed

Answer 7

-many owners wish to geld horses as yearlings
-use as 3-day event horses
-assess stride length which is presumably correlated to later performances in 3 day event trials (rarely compete with stallions)