Selection of Breeding
Program
An S 426
Fall 2007
Selection of Breeding Program

Setting of goals is of major importance and
includes goals for:
1.
2.
3.
4.

Reproduction
Calf performance
Income
Etc.
Breeding management will impact each of above
in varying degrees:
1. Breeding management practice with greatest
impact on reproduction is crossbreeding
2. Selection is best management practice for
improving carcass quality
Selection of Breeding Program
Once goals established, herd assessment
is needed – where is herd at

1. Determine breed makeup
2. Determine production level – need accurate records
3. Determine average weight and frame size of cow
herd
Larger frame cows have higher maintenance
costs

Table 1. Frame relationship to mature size and carcass weight
Frame
Score
3
4
5
6
7
8
9
Yearling Hip Height (in)
Expected Weight (lbs)
Bulls
Mature
Cows
1025
1100
1175
1245
1320
1395
1465
45
47
49
51
53
55
57
Heifers
43
45
47
49
51
53
55
Steer
Harvest
950
1050
1150
1250
1350
1450
1550
Steer
Carcass
600
660
725
785
850
915
975
Figure 1. Comparison of growth curves of small and large framed cattle.
Selection of Breeding Program

Larger frame feedlot cattle
1. Grow at faster rate
2. Require greater amounts of feed and in feedyard
longer, thus greater expenses
3. Heavier finish weights generate more income
4. Real problem if variation in frame sizes in same
feedyard, may need to sort for:
a.
b.
Selection of Breeding Program

Genetic change
1. Genetic change may not result in improved animals
2. Genetic improvement means superior animals with
greater profitability
Brought about in two ways:
1.
2.
Selection of Breeding Program

Selection – factors affecting:
1.
2.
3.
4.
Variation –
Heritability –
Selection differential –
Generation interval –
Predicting genetic change =
Genetic change per year =
Progress through selection dependent upon
number of traits selected

where n = number of traits selected
Selection of Breeding Program

Single-vs. multiple-trait selection
Single-trait selection produces rapid genetic change, but
unfortunately likely results in undesirable changes in
correlated traits
Increasing frame size resulted in increased:
1.
2.
3.
4.
Selection of Breeding Program

Multiple-trait selection first step towards more
effective selection, but challenges remain:
1. Rate of improvement in any one trait decreases
2. Unfavorable genetic correlations remain for economic
relative traits (ERT)
Selection of Breeding Program

Multiple-trait selection first step towards more
effective selection, but challenges remain:
3. Methods
a. Tandem – emphasis on one trait until desired level
attained and then move to next trait
b. Independent culling
- choosing minimum or
maximum levels for each trait
- more traits added, more relaxation occurs in order
to find animals meeting criteria
- once thresholds identified, application of this
method is easy and popular
Selection of Breeding Program
3. Methods
c. Selection indexes – incorporate the cost and income
resulting from production
1.) A description of every index should include:
a.) Traits included in the index
b.) Description of information used in the index, such
as EPD or individual phenotypic performance
c.) source of economic information and performance
levels used to calculate economic weights
d.) Relative economic emphasis of each trait to the
overall index
Selection of Breeding Program
c. Selection indexes – incorporate the cost and income
resulting from production
2.) Successful application of generalized indexes relies
on logical implementation:
a.) Identify production and marketing system
1.) When will animals be marketed (at what age)
2.) How will animals be marketed
3.) What is current performance and genetic level of
herd
Selection of Breeding Program
c. Selection indexes – incorporate the cost and income
resulting from production
2.) Successful application of generalized indexes relies
on logical implementation:
b.) Identify the index appropriate to the production
system outlined above - questions to be addressed
1.) What traits are included in the index
2.) What are the relative economic values used to
weigh the traits
3.) Decide on the appropriate index for evaluation
based on the most similarity between above points 1 and 2
Selection of Breeding Program
c. Selection indexes – incorporate the cost and income
resulting from production
3.) Most breed selection indexes are generalized for
overall breed improvement and use average costs and
income from production rather than accounting for a
specific producer’s marketing and production systems
a.) Has led to the development of Interactive
Decision Support (IDS) systems which allow breeders to
input parameters specific to their production systems – two
classes:
Selection of Breeding Program
1.) Herd – level systems
a.) Designed to evaluate overall genetic changes in herd
level – not individuals
b.) Angus Assoc. Optimal Milk Model – designed for
producers to decide the appropriate range of milk EPD
given the mature weight of their cows, annual cow costs
and variability in feed resources
Selection of Breeding Program
2.) Individual animal systems
a.) Designed to evaluate individual animal selection
decisions and the impact of those decisions on profitability
b.) Charolais Assoc. Terminal Sire Profitability Index
(TS) – designed to evaluate the selection of sires based on
their relative impact on profitability in a terminal sire mating
system; allows input of current herd production
characteristics and sources of income by the producer
Selection of Breeding Program

Mating systems
1. Inbreeding –
a. Main genetic effect is to increase the number
of pairs of homozygous genes
b. Usually results in a decline in traits related to
physical fitness
1.)
2.)
Selection of Breeding Program

Mating systems
2. Outbreeding –
a. Main genetic effect is to increase the number
of pairs of heterozygous genes
b. By increasing heterozygosity there is a
tendency to cover up detrimental recessive genes and
improve traits related to physical fitness
1.)
2.)
Selection of Breeding Program

Mating systems
Crossbreeding –
two reasons for its use:
1. For certain traits may result in heterosis
2. Breed complementarity
Selection of Breeding Program
Table 1. Summary of heritability and level of heterosis by trait type. A
Trait
Carcass / end product
Skeletal measurements
Mature weight
Growth rate
Birth weight
Weaning weight
Yearling weight
Milk production
Maternal ability
Reproduction
Health
Cow longevity
Overall cow productivity
a
Adapted from Kress and MacNeil. 1999
Heritability
Level of Heterosis
Medium
Medium
(5 to 10 %)
Low
High
(10 to 30 %)
High
Low
(0 to 5 %)
Selection of Breeding Program
1.
For certain traits may result in heterosis
average of
average of
a. % heterosis =crossbred - purebreds x 100
average of purebreds
1.)
b. Traits not expressing heterosis will equal the average
of the parent breeds for that trait in the crossbred offspring
Selection of Breeding Program
1.
For certain traits may result in heterosis
c. Why important in beef cattle business
1.) Largest benefit to commercial production is
crossbred cows – improves:
a.)
b.)
c.)
d.)
d. Keys for successful crossbreeding program:
1.)
2.)
e. Crossbreeding systems
Selection of Breeding Program
Breed complementarity – implies using breeds in
a crossbreeding program where their strengths and
weaknesses complement one another
2.
a. Example
1.)
Selection of Breeding Program

Composite breeds –
1. Maintain heterosis
2. Utilize breed complementarity
3. Once formed, can be managed like a purebred herd
Formed
from
2-breed
3-breed
4-breed
Retained %
maximum heterosis
50
67
75
Improved produc.
of cow herd(%)
12
15
17
Table 1. Breed performance levels for seven traits in beef cattle.
a,b.
Table 2. 2004 Adjustment factors to add to EPD of 15 different breeds to
estimate across-breed EPD. a,b.
Breed
Angus
Beefmaster
Brahman
Brangus
Braunvieh
Charolais
Gelbvieh
Hereford
Limousin
Maine Anjou
Pinzgauer
Red Angus
South Devon
Salers
Shorthorn
Simmental
Tarentaise
Birth Weight
0.0
9.7
13.0
5.7
6.5
10.5
5.4
3.4
4.5
6.7
7.7
3.6
6.7
4.9
7.8
6.4
3.6
Weaning Weight
0.0
39.0
34.8
20.0
30.0
38.4
7.1
-2.0
1.8
17.6
28.3
-1.4
21.7
30.7
31.4
22.4
30.1
Yearling Weight
0.0
37.9
-4.4
20.4
13.9
53.4
-21.1
-13.7
-19.9
5.5
25.5
0.7
40.8
46.1
44.5
21.9
13.4
Milk .
0.0
--24.6
--22.2
2.6
1.7
-17.8
-15.9
7.6
6.1
-7.8
3.5
9.0
12.1
10.0
17.8
Van Vleck and Cundiff, 2004
b Updates to across-breed EPD adjustments can be found at www.beefimpovement.org
a
Table 3. Average across-breed EPD for nonparent animals born in 2002-2003 by
breed. a.
Breed
Angus
Beefmaster
Brahman
Brangus
Braunvieh
Charolais
Gelbvieh
Hereford
Limousin
Maine Anjou
Pinzgauer
Red Angus
Salers
Shorthorn
Simmental
South Devon
a
Birth Weight
2.6
10.1
15.1
7.7
7.6
12.0
6.4
7.2
6.9
9.2
7.6
4.1
7.8
6.7
9.7
6.4
Weaning Weight
35
45
51
41
37
57
44
33
36
34
29
27
34
44
65
40
Yearling Weight
65
49
22
54
21
85
48
46
44
37
26
49
60
66
102
45
Adjustment using the 2004 across-breed EPD adjustments listed in Table 2.
Milk
17
--32
--22
8
19
-5
2
11
5
6
12
11
18
16
.
.
Selection of Breeding Program

Successful breeding program depends on:
1.
2.
a.
b.