sheep genetics lec 2

Question 1

What are the three options for genetic improvement?

Answer 1

1. remain with current stud
2. change ram source
3. change ram and purchase ewes

Question 2

what are the advantagaes and disadvantages of staying with the same stud?

Answer 2

direction will follow stud’s breeding objective

Question 3

what are the advantagaes and disadvantages of changing the ram source?

Answer 3

greater heterosis, potentially quicker rate of change

Question 4

what are the advantagaes and disadvantages with changing ram source and purchasing ewes ?

Answer 4

rapid progress but costly

Ewes biggest change more quickly

Question 5

what tools can you use in changing the ram source (5)?

Answer 5

Bloodline comparisons (ASBV and ESBV)
Stud’s breeding objective
Sire evaluation (merino select merino super sire using BV
On-farm trials (Benchmarking current ram source against one or more other ram sources)
Merino Select (ASBV database for merinos)

Question 6

what is the relationship between FD, FW and $ income?

Answer 6

increase in FD = decrease in FW

decrease FD= increase $ income

Question 7

what are the 4 things to consider when choosing bloodlines?

Answer 7

1. breeding objective (own and selected)
2. benchmark current lines
3. consider all traits
4. possible constraints

Question 8

what are possible constraints when selecting bloodlines?

Answer 8

Price
–Availability
–Distance
–available information

Question 9

how much do bloodlines vary?

Answer 9

o	FD 
	+2 to -3.5 micron
o	FW
	+15 to -20%
o	$GM/dse
	+18 to -$5 

+ 19.4% to -12.4 % the average return being recorded

Question 10

what is the CTSE and what is its purpose?

Answer 10

Breeding performance of sires measured by evaluating progeny

each sire mated to 50 ewes

Question 11

what is the prupose of a link sire?

Answer 11

• 1 link sire/7sires
  o Link sire already evaluated
  o Act as genetic connection b/w years and site

Question 12

how is the performance of the CTSE evaulated?

Answer 12

• Performance assessed twice
  o 10-16months, 17-24 months
  o Fleece testing
  o Visual by 2 sheep classers