Genomics breeding value excellent prediction tool Article previously published in the independent farmers weekly “Boerderij�
The breeding value of bulls based on their daughters hardly deviates from their genomic breeding value. The level of individual traits is also unaffected.
In breeding circles genomics is a trending topic. However, it
The debate focuses on whether the genomic breeding value
is nothing more than a method that provides extra information
(gBv) is reliable enough to allow young bulls to already be
in addition to the expectation value given to young bulls that
used as sires based on this value. To investigate whether
is derived from the breeding values of their sire and dams.
and how the genomic breeding values alter, CRV compared
And, as figures from CRV reveal, that system functions very
the last breeding values of 322 bulls with their own genomic
well, as the breeding value based on daughters hardly
breeding value. 64 of these bulls were awarded their first
deviates from the genomic breeding value. The genetic
breeding value in December 2010; 97 in April 2011; 87 in
information boosts the reliability of the expectation values
August 2011 and 74 in December 2011. The average reliability
from 35 percent to some 60 percent (see graph).
of the breeding values of all these bulls (based on daughters)
Using markers the employees at the Animal Evaluation Unit
is 78 percent.
process the genetic data of traits using a plus or minus on the expectation values. This increases the reliability of the
Genomic breeding value retains its worth
breeding value to some 60 percent, and later on up to 75
Firstly, it appears that the average breeding value based
percent when the first breeding value based on daughters
on daughters is around the figure indicated by the genomic
follows. As the number of daughters increases, the reliability
breeding value. The second graph below shows for the total
increases with each successive index.
conformation trait that with bulls noting a genomic breeding
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Genomics breeding value excellent prediction tool
value of 105 will have breeding value figures between 100
CRV determines these differences for several traits (table 3).
and 110 based on their daughters. As the level rises or falls,
The very slight deviation per trait is striking. Analysis shows
the deviation remains more or less the same; but does shift
that 70 to 90 percent of the bulls will be placed in the same
in line with the values. In other words: a bull with a genomic
class or higher based on their genomic breeding values, as
breeding value of 101 will never be given a breeding value of
they would be based on the daughters. There is a degree of
113 for total conformation based on daughters, or vice versa.
variation, but the risk of being disappointed is small.
For Theo Gieling, international breeding specialist at CRV, this represents a breakthrough. „You see that the average
Young breeding bull or genomics bull
level corresponds, but also if examined at trait level, the
In practice, farmers are not afraid of huge differences
bull performs at the same level he scores with his genomic
between the classic breeding values compared with the
breeding value.� And it’s not just the extreme figures that
genomic values. According to Gieling, approximately 35
count. In the upper right of the table at breeding value NVI (in
percent of all inseminations using CRV bulls are already done
English: Dutch-Flemish Index) the number of bulls is shown
using InSire animals (young bulls with a genomic breeding
that fall in a certain class genomically as well as being in the
value). 65 percent of them are InSire Top Bulls; specially
same class with their breeding value based on daughters.
selected young bulls that are available separately on the
Roughly half of the bulls stay in the same class. About a
CRV bull chart. Many farmers already opt for bulls with a first
quarter is relegated to a lower class, while another quarter
or second breeding value of some 75 percent reliability.
is promoted to a higher class. For the individual traits too,
Even so, Gieling says that farmers should remain alert and
the average of the last breeding value per level is virtually
not rely on a single bull. The individual breeding value has
identical to the level of the genetic breeding value calculated
a reliability of 60 percent; the ultimate breeding value may
earlier. A number of examples of this are shown in table 3.
differ. If the aim is higher milk production and you select a
For instance, 85 bulls in the class 15-24 kg protein have an
group of bulls that inherit a lot of milk, you will get daughters
average genomic breeding value of 19.1 kg protein. Based
that also perform well in that area too. For bulls with a high
on the daughter information, these same 85 bulls arrive at an
positive status for milk based on their average genomic
average of 20.6 kg protein. The total shows that the breeding
breeding value, will show the same profile when they have
value of 321 bulls based on daughter only deviates by just
breeding values based on daughters.
0.8 kg protein.
Author: Wynand Hogenkamp
First breeding value stays close to genomic breeding value
reliability of breeding values (in %) with bulls at different ages
comparison of genomic breeding value with last breeding value based on daughters for total conformation trait
most recent breeding value
Increasing reliability
100 80 60 40 20 0
test bull
genomic proven proven bull bull (1st yr.) bull
115 110 100 95 90 0
96
98
100
102
104
106
108
110
112
114
genomic breeding value
The reliability of the breeding value of young bulls increases as CRV uses the genetic data of the animal itself alongside the parent data (left). The reliability increases as soon as daughter data becomes available. The second graph shows that the average breeding value based on daughters is around the figure indicated by the genomic breeding value.
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Genomics breeding value excellent prediction tool
1. Majority of bulls stay in same class comparison of shift in class of genomic breeding value compared with last breeding value based on daughter for NVI trait NVI genomics NVI daughters
-100 – 51
-50 – 1
0 – 49
-100 – 51
1
3
3
-50 – 1
1
8
16
4
0 – 49
1
15
38
23
3
4
21
66
23
1
115
7
22
39
4
72
3
11
3
1
18
118
76
8
1
321
50 – 99 100 – 149 150 – 199 totaal
3
30
85
50 – 99
100 – 149
150 – 199
200 – 249
totaal 7 29 80
The majority of bulls that fall in a certain class based on genomic breeding value, would also fall into the same class using the breeding values based on daughters.
2. Difference in breeding values small
3. Averages show practically no shift
last breeding value with daughter data compared with genomic breeding value trait difference
comparison of the various classes within three traits number of bulls
genomics
daughters
95 – 99
13
98.2
97.2
100 – 104
147
102.3
102.0
105 – 109
138
106.6
105.9
110 – 114
24
110.6
110.0
Total/av.
322
104.6
104.1
-50 – 0
55
-21
-13
0 – 50
142
27
34
50 – 100
101
72
75
100 – 150
21
120
107
Total/av.
319
40
45
9
-7.9
-8.9
Trait
Difference
class
Reliability NVI
+17.1
Total conf.
NVI
+1.4
Kg milk
-2.9
Kg fat
+1.6
Kg protein
+0.8
Longevity
-12.6
Total conformation
-0.5
Frame
-0.6
Dairy strength
-0.4
Udder
-0.3
Feet and legs
-0.3
Somatic cell count
+0.1
Fertility index
+0.2
The average breeding value based on daughter data (rel. = 78 %) is slightly better for NVI, kg fat and kg protein than the calculation based on the genomic information (rel. = 61 %).
Inet
Kg protein -15 – -6 -5 – 4
49
-0.2
0.9
5 – 14
98
9.9
11.8
15 – 24
85
19.1
20.6
25 – 34
56
29.0
27.3
34 – 44
20
38.2
37.2
45 – 54
4
50.0
55.0
Total/av.
321
15.9
16.7
The average value determined based on genomic traits is practically identical to the average value based on daughter data.
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