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Every five years the national average for every trait is updated to account for genetic change in the population
genetic progress made in recent years within the National Herd. Figure 1 illustrates that progress in the Holstein cow population from 2000 to 2012, for the important type composites. The year on year improvement illustrates UK herds’ strong and positive focus on health, welfare and longevity in cattle breeding. In the 12 year period shown, the UK Holstein population has improved by an entire point for overall type merit, which demonstrates the emphasis placed on type traits by UK breeders.
Table 1: Change in Holstein type trait values between the 2010 and 2015 bases
Trait
Type merit composite Mammary composite Legs & feet composite Stature
Chest width Body depth Angularity Rump angle Rump width Rear leg side Foot angle
Fore udder attachment Rear udder height Udder support Udder depth
Front teat placement Teat length
Rear teat placement Teat position side Temperament Ease of milking Locomotion Condition
Base
change -0.72 -0.69 -0.56 -0.60 0.04 -0.27 -0.37 -0.03 -0.49 0.19 -0.27 -0.60 -0.67 -0.48 -0.51 -0.42 0.03 -0.22 -0.10 -0.40 -0.43 -0.62 0.24
When was the base change for production traits?
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This time around the
production base change took place in August 2014. Normally, production and type base changes would occur at the same time. However, with the introduction of a new PLI format in 2014, the type base change was delayed until April 2015, to allow the new PLI to bed in.
How big will the January base change be? Overall type merit for Holsteins will change by -0.72 points, while the mammary composite will change by -0.69 points and Legs and Feet by -0.56 points. The base change, from 2010 to 2015, for each trait and composite is shown in Table 1. Friesian composites will change by about -0.1 points. For those interested in converting between Holstein and Friesian type proofs, a full set of conversion formulas are available within the ‘Documents’ part of the ‘Animal Data’ section on the Holstein UK website.
Are all traits affected? Yes all traits are recalibrated with the base change, however, some will not alter greatly as shown in Table 1. Where an optimum is desired, such as rump angle, the population average does not vary much over time. On the other hand where improvement is desired, such as mammary traits in particular, considerable increase in scores has taken place, as shown by the strong positive genetic trend for the mammary composite in figure 1.
How does the change in individual traits compare with last time in 2010?
The pattern of change is broadly similar to that of the last base change in 2010. A few traits show a slightly greater improvement this time around, such as fore udder attachment, rear udder height, ease of milking and locomotion. The rate of decrease in chest width has slowed down, to the extenthere is almost no change this time around (Table 1), while the rate of increase in rump width is slightly greater than in 2010.
Have Type proofs changed for foreign sires? Yes, sires with semen imported into the UK have their proofs expressed on the UK base and will also, therefore, be subject to the base change.
Remember that UK type scores, either for an individual
trait or composite, are the only accurate way of assessing the genetic merit of a foreign sire, when breeding to UK Holstein cows in UK conditions. For more information and for all updated April 2015 UK Type and
Production proofs, visit the Holstein UK Website when the proofs will be made live on Tuesday the 7th of April 2015. On the website you will also find an easy, free and independent way of searching, short listing and creating your own lists using the BullSelector or WebMate tools.
THE JOURNAL APRIL 2015 15
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