Genetics

Question 1

Genetic improvement requires variability. What is the equation for variation in population?

Answer 1

Variation in population = variation in genetics + variation in environment

Question 2

What are contemporaries?

Answer 2

An animal’s performance compared to another animal treated in a similar way
(Positive, negative, or zero compared to mean)

Question 3

What is the genetic condition BLAD?

Answer 3

Bovine leukocyte adhesion deficiency

Causes fewer neutrophils to enter tissues, but higher numbers in circulation

Question 4

What is the genetic condition CVM?

Answer 4

Complex vertebral malformation

Misshapen or fused vertebrae around cervicothoracic junction, with symmetrical arthrogryposis of limbs

Question 5

What are haplotypes? Give an example

Answer 5

Set of DNA variations (polymorphisms) that tend to be inherited together
E.g. Holstein haplotype for cholesterol deficiency

Question 6

How does Holstein haplotype cholesterol deficiency differ between heterozygous and homozygous animals?

Answer 6

Heterozygous - reduced cholesterol

Homozygous - no cholesterol, death within months

Question 7

Give 3 examples of highly heritable traits

Answer 7

Udder morphology
Milk fat/protein
Body conformation

Question 8

Give 2 examples of traits with medium heritability

Answer 8

Milk yield

Growth rate

Question 9

Give an example of a trait with low heritability

Answer 9

Repro traits

Question 10

What is pleiotropy?

Answer 10

Genes affecting more than 1 trait