2010 Base Change for National
Dairy Genetic Evaluations
Kentucky
Dairy Notes
March 2010
Genetic change keeps happening in U.S. dairy breeds as a result of the
selection decisions made by dairy producers and the AI organizations who
choose the parents of the next generation of AI young bulls. This makes it
necessary to change the bases for the genetic evaluations of dairy cows
and bulls so that bulls and cows can be fairly evaluated over time. The
first updating of genetic bases took place in 1965 and has continued until
this latest base change for 2010. In fact, the last three base changes have
taken place on 5 year intervals – one in 2000, one in 2005 and one in
January of this year 2010. The base group for each of the most recent
base changes is the cows born 5 years earlier. That means for 2010 the
base is cows born in 2005. The idea here is for the base of genetic
evaluations to be a relatively recent cow population.
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The base change represents the change in predicted transmitting abilities
(PTA’s) of the traits in the Net Merit $ index (such as yield traits,
productive life, somatic cell score and daughter pregnancy rate) as well as
19 individual type traits. The base change is calculated separately for the
6 U.S. dairy breeds – Holstein, Jersey, Brown Swiss, Guernsey, Ayrshire
and Milking Shorthorn. Base changes for calving difficulty are calculated
for the Holstein and Brown Swiss breeds and a base change for stillbirth
rate is only calculated for the Holstein breed. The base changes for these
two traits are for bulls born in 2005 compared to bulls born in 2000.
Jack McAllister.
The table below shows the base change in PTA progress for each dairy
breed and for all of the traits on the Net Merit $ index.
University of Kentucky
(859) 257-7540
amcallis@uky.edu
PTA progress (2005 − 2000 birth year)
Holstein
Jersey
Brown
Swiss
Guernsey
Ayrshire
Milking
Shorthorn
Lifetime $
132
119
60
50
37
71
Protein
Pounds
14
12
10
6
3
6
Fat
Pounds
15
17
10
12
3
8
Milk
Pounds
417
323
267
231
53
199
Productive life
Months
0.6
0.8
0.3
0.1
0.3
0.8
−0.01
0.00
0.01
0.02
−0.02
0.01
Trait
Unit
Net merit
Log
Somatic cell score
(base 2)
Daughter pregnancy
rate
%
0.0
−0.1
−0.5
−0.4
0.1
−0.1
Service sire calving
difficulty
%
0.4
…
0.4
…
…
…
Daughter calving
difficulty
%
−1.0
…
−0.5
…
…
…
Service sire stillbirth
rate
%
0.2
…
…
…
…
…
Daughter stillbirth rate
%
−0.4
…
…
…
…
…
Udder composite
0.85
0.40
0.25
0.30
0.35
0.25
Feet and legs
composite
0.65
0.20
0.10
0.30
0.15
0.15
Body size composite
0.60
0.15
0.30
0.35
0.30
0.10
Dairy composite
0.75
…
…
…
…
…
Source: VanRaden et al. Genetic base changes for January 2010. 2009. AIPL Res. Report Base2 (8-09).
Progress for Holstein PTA service sire calving difficulty and stillbirth is the change
between bulls born in 2005 and those born in 2000; progress for Holstein PTA daughter
calving difficulty and stillbirth rate is the change between bulls born in 2000 and those
born in 1995. For Brown Swiss, PTA progress for service sire calving difficulty is
calculated as the change between bulls born from 2001 through 2005 and those born
from 1996 through 2000; PTA progress for Brown Swiss daughter calving ease is the
change between bulls born from 1996 through 2000 and those born from 1991 through
1995. Brown Swiss bulls had to be grouped because of their limited numbers.
Kentucky
Dairy Notes
March 2010
The Holstein and Jersey breeds have made the most genetic progress from
2000 to 2005 in the Lifetime Net Merit $ index of $132 and $119, respectively.
That is a change of $26 and $24 per year respectively. Change in milk, fat and
protein yield was the greatest for Holsteins, Jerseys and Brown Swiss with
these breeds increasing fat + protein yield by 29, 29 and 20 pounds
respectively. All breeds made important progress in productive life with the
Jerseys and Milking Shorthorns having an increase of 0.8 months and
Holsteins an increase of 0.6 months.
Change in type traits was apparent for all breeds but the greatest change in
udder composite, feet and legs composite and body size composite was for
Holsteins. Stature increased in all the dairy breeds with the Milking Shorthorn
increase being the greatest (data not shown). Final type score (not shown)
increased for all breeds but was the greatest for Holsteins, Jerseys and
Guernseys.
The generally positive change for all dairy breeds for both production and
economically important non-production traits is encouraging.
Educational programs of Kentucky Cooperative Extension serve all people regardless of
race, color, age, sex, religion, disability, or national origin.
For More Information
Please Contact:
Jack McAllister.
University of Kentucky
(859) 257-7540
amcallis@uky.edu