ANSC 3335 - GENETICS OF LIVESTOCK IMPROVEMENT
3rd EXAMINATION (100 points)
Spring 2010
I. GENETIC PROBLEM SOLVING:
A.
Refer to the following actual pedigree of a linebred calf.
For your convenience, I have added numbers in parentheses
besides the names of some of the animals. (30 points)
(Formulas: FX = Σ[(½)n1+n2+1(1 + FCA)], RX,Y = Σ[(½)n1+n2(1 + FCA)] )
Nocona (1)
03M (3)
Buddy (7)
2
4
S
5
Ginger (8)
6
X
Nocona (1)
D
5
Ginger (8)
1) Draw
points)
an
arrow
6
diagram to
the
right
of
the
pedigree.
(5
Identify the common ancestor(s). What type of relationships are
reflected in the pedigree? (5 points)
2) Calculate FX (inbreeding of animal X).
value.
(10 points)
Interpret your FX
3) Calculate RX1 (genetic relationship
Interpret your RX1 value. (10 points)
between
X
and
1).
B.
Below are performance figures of purebred and crossbred
turkeys for body weight (BW) at market age: (25 points)
Breed group
Bourbon (B)
Bronze (Z)
B X Z
Z X B
(BW)
30
35
33
34
1) Calculate the percentage hybrid vigor for this trait.
Interpret this value. Identify the best maternal breed. Explain.
(5 points)
Formula:
_
_
[ PF1 - PP ]
%HV = __________
_
PP
X 100
2) For body weight in turkeys, predict levels of potential
individual and maternal heterosis on a percentage basis. Then,
calculate the total (cumulative) heterosis effect (lbs). Provide
values of F1 heterosis (individual = +0.46 and maternal = +0.22
lbs) for each of the following matings involving breeds B, Z,
and W (White). (10 points)
Total
(cumulative)
Individual
Maternal
heterosis
heterosis, % heterosis, %
effect, lbs
a. B sire x Z dam
b. BZ sire x W dam
c. BZ sire x BW dam
d. Z sire x BBZ dam
n
Formula: %RHV = (1- Σ psipdi)  x 100
i=1


3) Explain why heterosis
heterosis. (10 points)
II. SHORT ESSAY:
is
cumulative.
Define
maternal
(20 points)
A. Discuss the difference between inbreeding and linebreeding.
Also, why is inbreeding based on common ancestry?
B. List and briefly discuss the pros and cons of rotational and
terminal crossbreeding systems. Also, from a gene action
standpoint, what distinguishes a dam from a sire breed?
III. TERMS: Define and either mention its importance or provide
an example of the use for each term below: (25 points)
1) Inbreeding depression 2) Prepotency 3) Arrow diagram 4) Heterosis 5) Breed complementation -