Transcript Possible selection criteria for improved cow fertility

F.W.C. Neser
Country
% Off-take
South Africa (Commercial)
32
South Africa (Emerging)
21
South Africa (Communal)
6
Australia
28
New Zealand
37
European Union
34
USA
38
Argentina, Uruguay
30
Brazil
22
Source -National beef Cattle Sector Strategy and Implementation Framework – February 2006
Communal Commercial
Stud
Calving %
40%
65%
85%
Pre-wean mortality
50%
4%
2%
Post-wean mortality
15%
2%
2%
Calves wean/annum/25 cows
5
16
21
Calves available for sale
2
15
20
Average weight
150kg
180kg
205kg
Price/kg
R9.00
R20.60
R21.25
Potential monetary value
R2700
R55620
R86100
Potential monthly income
R225
R4635
R7175

Fitness = NATURAL SELECTION:
 Survival
 Fertility
The heritability of fitness traits are usually
low and will be severly influence by
inbreeding
depression
and
heterosis
(Bourdon, 1997)
Unlike the dairy farmer, the beef farmer
derives his entire income from calves
born into the herd, making fertility
unquestionably the most important trait.
Results of a study placed the economic
importance of fertility, growth rate and
carcass quality in the ratio 10:2:1. This
means that fertility is 5x more important
than growth and 10x more than carcass
quality (Dr G Coulter-Kanada)
400,000
380,000
360,000
340,000
320,000
300,000
280,000
260,000
65%
75%
Medium Frame Weaner
85%
95%
Farm size
Stocking rate
Weaner price
Carcass price
Price of C grades
1000ha
6ha/LSU
R 17.00
R 27.00
R 23.00

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
All animals are equally
fertile
It is impossible to
improve fertility by
selection
Feed your animals fertile
Model
P = μ + G + E
Genotype
Environment
Phenotype
Nutrition & management that affect the animals in the
herd now!

Cows:
•
manage heifers to attain mating weights (65% of adult weight)
•
manage 1st calf cows (e.g. early weaning & mate separately)
•
restrict joining & cull empties
•
control reproductive diseases
•
cull females having difficult births

Bulls:
•
breeding soundness test (adequate scrotal size)
•
good physical structure (and sheath)
•
adequate pre-breeding nutrition (body condition)
•
control reproductive diseases
•
multi-sire groups, mating ratios, serving
capacity
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Female fertility is a complex trait with many
components.
Each component use resources.
Nature select for intermediate optimum.
Holistic approach.
To much selection emphasis on production
could decrease reproduction
Less fertile
Did not calf
Above average fertile

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Age at first calving
(Optimum)
ICP: First and second calf
(Min)
Average lifetime ICP
(Min)
Days to calving
• whole herd recording (female inventory)
 bull in date and service sire(s)
 subsequent calving date
 record culls, especially non-calvers /culled
empty

Scrotal circumference
• measure scrotal circumference all young bull at around 400d
- Scrotal circumference also contributes to DC EBV
- Early indicator of DC EBV for young bulls
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Mating ability
Fertility
Performance of ancesters and daughters
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Age at puberty
Age at first calving
Days to calving
Calving interval
Calving ease
Days open
Gestation length
Longevity
Stayability
Scortal circumference
0.16 - 0.57
0.06 - 0.19
0.08 - 0.11
0.01 - 0.06
0.09 - 0.13
0.09 - 0.20
0.15
0.06 - 0.08
0.03 - 0.11
0.40 - 0.46
Trait
Conception rate
Pregnancy rate
Calving rate
Weaning rate
Days to calving
Conception rate
Pregnancy rate
Calving rate
Weaning rate
Days to calving
Production level
Brahman
0.77
0.76
0.72
0.62
h2
0.11
0.11
0.07
0.04
0.22
Tropical Composite
0.95
0.01
0.92
0.03
0.90
0.03
0.78
0.03
0.13
Trait
Mating1
Conception rate
Pregnancy rate
Calving rate
Days to calving
Weaning rate
Mating 2
Conception rate
Pregnancy rate
Calving rate
Days to calving
Weaning rate
Days to cycling
Lactation anoestrous interval
Lactation cyclicity
Lifetime annual calving
rate
Lifetime annual weaning
rate
0.61
0.60
0.50
-0.46
0.98
0.41
0.51
0.44
-0.54
0.99
0.90
0.75
0.89
-1.0*
0.86
-0.55
-0.71
0.59
0.76
0.69
0.81
-0.96
0.81
-0.60
0.62
0.53
Correlations show selection for reduced age at
puberty will result in increased reproductive
performance at both the early and lifetime
stages.
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Male:


Sperm quality
Hormonal levels
LH – Luteinising hormone
• Testosterone production
• Influences onset of puberty
Inhibin
• Regulation of sperm production
IGF-I – Insulin-Like Growth Factor-I
• Growth stimulus
• Bull SC and sperm motility and heifer puberty
Brahman
Category
h2
h2
Inhibin
0.74
0.72
Luteinising Horm
0.31
0.48
Insulin-like GF
0.44
0.36
Mass Activity
0.24
0.13
Semen Quality
Motility
0.15
0.15
18 months
% Normal
0.25
0.20
Hormone
Trait
Tropical
Composite
Burns and Corbet 2012
.
Bull trait
Hormones
Inhibin
Luteinising Hormone
IGF-I
Semen Quality
Mass Activity
Motility
%normal sperm
Scrotal and sheath
Scrotal circumference
Sheath score
Age
(Mths)
Pregnancy
Rate
Calving
Rate
Days
to calving
4
4
6
0.14
-0.01
0.29
0.24
-0.20
-0.01
-0.13
0.51
-0.11
18
24
18
24
0.42
0.34
0.45
0.26
0.42
0.32
0.43
0.50
-0.38
-0.37
-0.50
-0.43
12
18
24
18
0.16
0.14
0.14
0.29
0.35
0.24
0.25
0.11
-0.36
-0.34
-0.25
-0.12
Bull trait
Hormones
Inhibin
Luteinising Hormone
IGF-I
Semen Quality
Mass Activity
Motility
%normal sperm
Scrotal and sheath
Scrotal circumference
Sheath score
Age
(Mths)
L. Anoestrous
interval
Calving
Rate
Day
to calving
4
4
6
-0.08
-0.29
-0.21
0.14
0.33
0.20
-0.19
-0.29
-0.24
18
24
18
24
-0.27
-0.61
-0.52
-0.62
0.55
0.88
0.29
0.63
-0.24
-0.84
-0.21
-0.69
12
18
24
18
-0.19
-0.27
-0.09
-0.12
0.15
0.27
0.10
0.11
-0.19
-0.35
-0.12
-0.18
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No genetic antagonisms between semen
quality and production traits
Scrotal and semen traits are genetically related
to female age of puberty
Scrotal traits but especially semen traits related
to reproductive output in cows
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Recognition of novel phenotypes associated
with economically important traits
Determination if phenotype can be measured
accurately
Assessment of variation associated with
phenotype
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Proportion of variation attributable to genetics
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Programs to implement change
Birth
Year
Number
Exposed
Number
%
Pregnant Pregnant
1998
77
6
7.79
1999
122
1
0.82
2000
122
16
13.11
2001
142
27
19.01
2002
159
86
54.09
2003
159
77
48.43
2004
149
77
51.68
2005
162
57
35.19
2006
113
81
71.68
2007
151
110
72.85
2008
141
103
73.05
2009
166
124
74.70
2010
177
138
77.97

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Heifers should conceive first time and calf not
later than 33 months
Each cow should calf each year
(Herefords currently 384 days)
 95%

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Strive to use Days to Calving – Mating seasons
compulsory
DNA technology – Fertility markers
Traits
h2
r
Increase in
accuracy
Progeny
equivalents
Age at first calving
0.11
0.40
0.15
14
Heifer preg. Rate
0.24
0.32
0.07
6
Scrotal Circumference
(12mth)
0.38
0.28
0.12
3
Stayability
0.12
0.38
0.11
9
Accumulated production
0.20
0.27
0.11
10
Thanks