B7: Estimation of breeding value in dairy cattle

Question 1

What is the breeding value of an animal?

Answer 1

the deviation of the individual genetic merit from the mean genetic merit of a reference population.

BVi = GMi - GMpop

part of the circle of animal production

Question 2

What is aggregated breeding value?

Answer 2

a complex type of breeding value established for more than one trait simultaneously.

It is achieved upon base of a linear combination of breeding goal declared valuable traits.

Question 3

What is estimated heritability?
What are the factors to estimate it?

Answer 3

to calculate the value of a breeding animal.
-> dairy traits.
-> conformational traits.
-> health, fitness, metabolism.
-> repro traits.

Question 4

What are the dairy traits?

Answer 4

Primary dairy traits:
* Milk producing ability
* Milk yield, kg
* Relative milk yield, kg
* Milk composition, (see extra point)
* Milking ability

Chemical composition:
o Fat content (%)
o Protein content (%)
o PFR – Protein to fat ration
o FPD – Fat protein difference
o Lactose content (%)
o SCC (somatic cell count)

Question 5

What are the conformation traits required to estimate heritability?
Mention 2 forms of measuring conformation.

Answer 5

‣ Stature

‣ Strength

‣ Body: Body depth + Dairy form + Rump angle.

‣ Feet: Foot angle + Feet & leg score + Joint health.

‣ Udder Features: Udder attachment + Udder depth + Udder width + Udder cleft + Teat placement + Teat length.

2 forms of measuring conformation:
-> linear conformation scoring system on functional traits: 9 point scale.
-> Descriptive C scoring.

Question 6

What are the health, fitness and metabolism traits required to estimate heritability?

Answer 6

‣ Dry matter intake
‣ Body condition score
‣ Energy balance
‣ Incidence of mastitis, ketosis, retained placenta, metritis & other health conditions

Question 7

What are the reproductive traits required to estimate heritability?

Answer 7

‣ Age at first calving
‣ Calving interval
‣ Number of inseminations
‣ Days to first & last calving
‣ Interval of first luteal activity

Question 8

What is the genomial BVE?

Answer 8

strategy for applying genome-wide selection in diary cattle.

approx 80% accuracy.

can be calculated at birth.