Heterosis

1
Lecture 25
Heterosis
2
Computing Fractions
GH x Lab
(1/2) GH (1/2) Lab
(1) GH x (1/2) GH (1/2) Lab
(3/4) GH (1/4) Lab
(3/4) GH (1/4) Lab x (1/2) GH (1/2)
Lab
3
Computing Fractions
(3/4) GH (1/4) Lab x (1/2) GH (1/2)
Lab What is the expected fraction of GH and Lab
genes in a progeny resulting from this mating?
4
Heterosis

5
Heterosis
-- Additional performance ABOVE expectations for
progeny resulting from crosses of breeds, hybrid
vigor

6
Heterosis
-- Additional performance ABOVE expectations for
progeny resulting from crosses of breeds, hybrid
vigor
MALE FEMALE Hereford Simmental Hereford
Simmental
7
Heterosis
-- Additional performance FROM expectations for
progeny resulting from crosses of breeds, hybrid
vigor
MALE FEMALE Hereford Simmental Hereford 550
Simmental
8
Heterosis
-- Additional performance FROM expectations for
progeny resulting from crosses of breeds, hybrid
vigor
MALE FEMALE Hereford Simmental Hereford 550
Simmental 650
9
Heterosis
-- Additional performance FROM expectations for
progeny resulting from crosses of breeds, hybrid
vigor
MALE FEMALE Hereford Simmental Hereford 550
630 Simmental 650
10
Heterosis
-- Additional performance FROM expectations for
progeny resulting from crosses of breeds, hybrid
vigor
MALE FEMALE Hereford Simmental Hereford 550
630 Simmental 640 650
11
Heterosis
1) What is expected Average of the
purebreds
12
Heterosis
1) What is expected Average of the
purebreds PB H S 550 650
600 2 2

13
Heterosis
1) What is expected Average of the
purebreds PB H S 550 650
600 2 2 2) Average of
crossbreeds

14
Heterosis
1) What is expected Average of the
purebreds PB H S 550 650
600 2 2 2) Average of
crossbreeds CB H/S S/H 630 640 635
2 2


15
Heterosis
Notice CB - PB 35 lbs more than expected


16
Heterosis Heterosis CB - PB 100
5.83 PB



17
Heterosis Heterosis CB - PB 100
5.83 PB Notice Equation can be
arranged to allow for prediction



18
Heterosis Heterosis CB - PB 100
5.83 PB Notice Equation can be
arranged to allow for prediction CB 1
( Heterosis/ 100) PB





19
Reciprocal Cross Difference

20
Reciprocal Cross Difference
Note 1/2H 1/2S - 1/2S 1/2H 640 -
630 10 lbs
MALE FEMALE Hereford Simmental Hereford 550
630 Simmental 640 650
21
Reciprocal Cross Difference
Note 1/2H 1/2S - 1/2S 1/2H 10
lbs Causes 1) In males progeny X chromosome is
from different sources
22
Reciprocal Cross Difference
Note 1/2H 1/2S - 1/2S 1/2H 10
lbs Causes 1) In males progeny X chromosome is
from different sources 2) In all progeny
cytoplasmic DNA is different
23
Reciprocal Cross Difference
Note 1/2H 1/2S - 1/2S 1/2H 10
lbs Causes 1) In males progeny X chromosome is
from different sources 2) In all progeny
cytoplasmic DNA is different 3) Maternal
ability differs in raising calves
24
Dam
Sire
X chromosome to males
Progeny
Cytoplasm to all progeny
Maternal environment
25
Heterosis and Dominance
26
Heterosis and Dominance
Breeds Loci 1 2 3 1 2 3 4
5
27
Heterosis and Dominance
Breeds Loci 1 2 3 1 AA 2 BB 3 CC
4 dd 5 ee
28
Heterosis and Dominance
Breeds Loci 1 2 3 1 AA AA 2 BB BB 3
CC cc 4 dd dd 5 ee EE
29
Heterosis and Dominance
Breeds Loci 1 2 3 1 AA AA aa 2 BB BB
bb 3 CC cc cc 4 dd dd DD 5 ee EE ee
30
Heterosis and Dominance
Complete dominance at each locus A_ B_ C_
D_ E_ 1 aa bb cc dd ee 0
31
Heterosis and Dominance
Complete dominance at each locus A_ B_ C_
D_ E_ 1 aa bb cc dd ee
0 Purebreed 1 3 from AABBCCddee Purebreed 2
3 from AABBccddEE Purebreed 3 1 from
aabbccDDee
32
Heterosis and Dominance
Crossbreed 1 and 2
33
Heterosis and Dominance
Crossbreed 1 and 2 PB1 PB2 AA AA BB
BB CC cc dd dd ee EE 3 3


34
Heterosis and Dominance
Crossbreed 1 and 2 PB1 PB2 CB AA AA AA
BB BB BB CC cc Cc dd dd dd ee EE Ee
3 3 4



35
Heterosis and Dominance
Crossbreed 1 and 2
H (4 - 3) 100 3 33
36
Heterosis and Dominance
Crossbreed 2 and 3
37
Heterosis and Dominance
Crossbreed 2 and 3 PB2 PB3 AA aa BB bb
cc cc PB 2 dd DD EE ee 3 1



38
Heterosis and Dominance
Crossbreed 2 and 3 PB2 PB3 CB AA aa Aa BB
bb Bb cc cc cc PB 2 dd DD Dd EE ee E
e 3 1 4




39
Heterosis and Dominance
Crossbreed 2 and 3
H (4 - 2) 100 2 100
40
Heterosis -- value is usually higher for
lowly heritable traits
41
Heterosis -- value is usually higher for
lowly heritable traits -- value is usually
higher for more diverse breeds
42
Question
Distraction index
Labs GH Labs 0.58 0.48 GH 0.52 0.48
What is the heterosis for this trait?
43
Heterosis Retention
44
Heterosis Retention
S H 1/2S 1/2H


45
Heterosis Retention
S H S 1/2S 1/2H maximum
heterosis (100) 3/4S 1/4H
46
Heterosis Retention
S H S 1/2S 1/2H maximum
heterosis (100) 3/4S 1/4H
male female S S H
47
Heterosis Retention
S H S 1/2S 1/2H maximum
heterosis (100) 3/4S 1/4H
male female S S 1/2 SS H
48
Heterosis Retention
S H S 1/2S 1/2H maximum
heterosis (100) 3/4S 1/4H
male female S S 1/2 SS H
Retention 1 - P(alleles from same breed)
1/2 50
49
Heterosis Retention
3/4S 1/4H 1/2S 1/2H
50
Heterosis Retention
3/4S 1/4H 1/2S 1/2H
male female 3/4S 1/4H 1/2S 1/2H
51
Heterosis Retention
3/4S 1/4H 1/2S 1/2H
male female 3/4S 1/4H 1/2S 3/8
SS 1/2H 1/8 H
Retention 1 - 3/8 - 1/8 1/2 Heterosis 50
52
Heterosis Retention
Synthetic Breeds
53
Heterosis Retention
Synthetic Breeds male female 5/8 Angus 3/8
Brahman 5/8 Angus 3/8 Brahman
54
Heterosis Retention
Synthetic Breeds male female 5/8 Angus 3/8
Brahman 5/8 Angus (5/8)2 3/8 Brahman (3/8)2
Retention 1 - (5/8)2 - (3/8)2 .469
55
Question
What year did the spring celebration of the last
day of classes begin, first known as Spring
day and now as slope day ? 1901 1951 1981
56
Answers Computing Fractions
(3/4) GH (1/4) Lab x (1/2) GH (1/2)
Lab GH (¾) x (1/2) (1/2) x (1/2) 5/8 Lab
(1/4) x (1/2) (1/2) x (1/2) 3/8
57
AnswersHeterosis
0.50 0.53 0.53
heterosis
x 100
Answer - 5.7
58
AnswerSlope Day
Spring Day started in
1901
59
Rotational Crosses

60
Rotational Crosses
B A 1/2A 1/2B
61
Rotational Crosses
B A A 1/2A 1/2B 3/4A 1/4B
62
Rotational Crosses
B A A 1/2A 1/2B 3/4A 1/4B B 3/8A
5/8B
63
Rotational Crosses
B A A 1/2A 1/2B 3/4A 1/4B B 3/8A
5/8B
At equilibrium Progeny 2/3 Sire
breed Retention .67
64
Rotational Crosses
(SIRE)
A B 1/2A 1/2B
65
Rotational Crosses
(SIRE)
A B C 1/2A 1/2B 1/2C 1/4A 1/4B
66
Rotational Crosses
(SIRE)
A B C 1/2A 1/2B A 1/2C 1/4A 1/4B 5/8A
2/8C 1/8B
(MGS)
67
Rotational Crosses
At equilibrium Progeny 4/7 Sire breed, 2/7 MGS
breed, 1/7 other Retention .85
(SIRE)
A B C 1/2A 1/2B A 1/2C 1/4A 1/4B 5/8A
2/8C 1/8B
(MGS)
68
In General Numerator 1 2 4 8 2N -1
69
In General Numerator 1 2 4 8 2N
-1 Denominator 2N - 1
70
In General Numerator 1 2 4 8 2N
-1 Denominator 2N - 1 Retention 1 - 1
2N - 1
71
Example (n 5 Breeds) Numerator 1 2 4 8
16 Denominator 31 Breeds A 1/31 B 2/31 C
4/31 D 8/31 (Last Sire) E 16/31
72
Example (n 5 Breeds) Numerator 1 2 4 8
16 Denominator 31 Breeds A 1/31 B 2/31 C
4/31 D 8/31 (Last Sire) E 16/31
Retention .97