Download ANS 95433 Animal Breeding - An

Faculty of Graduate Studies
Master program in animal production
Advanced Animal Breeding (495523)
First Exam
Date: 14/4/2009
Instructor: Dr. Jihad ABDALLAH
Name:
Q1. (10 POINTS) Answer the following with True or False:
1. --------- Dystocia is an example of a simply inherited trait.
2. --------- Breeding value of an individual is the mean deviation of its progeny from the
population mean.
3. --------- In progeny testing, the accuracy of prediction of breeding value increases
more by doubling the number of records per progeny than doubling the number of
progeny.
4. --------- Producing ability measures the ability of the animal to repeat its performance
in future records.
5. --------- Standard error of the heritability estimate from the regression of offspring on
one parent is equal to the standard error of the regression coefficient.
6. --------- At a biallelic locus with no dominance, the additive variance is maximum
when allele frequency is 0.5.
7. --------- Three-factor interaction arises from interaction between alleles on three loci.
8. --------- Heritability estimate from offspring-dam regression is generally larger than
that estimated from offspring-father regression.
9. --------- It is more accurate to evaluate the breeding value of a bull using m half-sib
progeny than using m of the half sibs of the bull
10. ---------- The genetic covariance between half-sibs is equal to half the additive
variance.
Q2.
a) (2 POINTS) Mention two differences between simply inherited traits and polygenic traits
b) (2 POINTS) What does heritability in the narrow sense measure?
c) (3 POINTS) Give an example on each of the following:
1- A trait with low heritability:
2- A trait with moderate heritability:
3- A trait with high heritability:
1
Q3. (8 POINTS) The following are mean genotypic values at a single locus:
Genotype
aa
Aa
AA
Genotypic value
40
60
60
Assuming that q (the frequency of allele a) is 0.4
a) Find the overall mean of the population.
b) Average effect of each allele and average affect of gene substitution
c) The breeding value and the dominance deviation for each of the three genotypes.
d) The additive and dominance variances.
2
Q4.
a) (4 POINTS) the following data were obtained for a repeated trait:
Phenotypic variance = 120, Additive variance= 40, Dominance variance = 8, Epistasis
variance = 2, and temporary environmental variance =60.
If the variance due to maternal and common environmental effects is equal to 0, find:
1. The heritability in the narrow sense
2. The heritability in the broad sense
3. The repeatability
b) (5 POINTS) In a progeny test, a dairy bull has 60 paternal half-sib progeny each with a
single record. Suppose that the average of milk records on the 60 daughters is 8000 kg and the
population average is 6000 kg. Assuming that the heritability of milk yield is 0.30; compute
the breeding value of the bull from this information and the accuracy of the prediction.
3
Q5. (6 POINTS) For the following pedigree, calculate the additive relationship coefficients
among all the animals using the tabular method.
O
A
C
B
D
4
Q6. (10 POINTS) Use the following ANOVA table to estimate variance components and
heritability. Compute the standard error of the heritability. (Hint: balanced design with 4
sires, 4 dams per sire, and 5 progeny per dam).
Source
SS
MS
Expected
MS
3
1000
250
 E2   2 D2  3 S2
Between dams within
sires
12
1200
100
 E2  1 D2
Between progeny within
dams
64
5760
90
TOTAL
79
7960
Between sires
d.f
 E2
5