More Genomic Breeding Values on the German scale
What is RZG and gRZG?
RZG (Relativ-Zuchtwert Gesamt) is the total merit index for dairy breeds in Germany, Luxembourg and Austria. The gRZG is the genomic enhanced total merit index. Relative weighting of trait complexes is based on economic importance including functional conformation (body, feet&legs and udder). Health traits were incorporated in April 2021.
What are the benefits of using gRZG?
The gRZG is mainly focused on the breeding goal for Holsteins and on a profitable milk production. In addition to this,the vit provides the economic Total Merit Index RZ€ which only includes traits that influence the profitability of milk production directly. Using either gRZG or RZ€ as selection goal will maximize the profit of dairy farming.
The RZG is distinguished by
- Economically balanced weighting of milk production improvement and functional (= cost saving) traits
- Direct health traits which include udder health, claw health, reproductive health and metabolic stability based on diagnoses from a large genomic training set. A total of 13 cow traits are represented in the 4 complexes. Besides those mentioned, young stock survival is included as a separate breeding value.
- Functional conformation (body, feet&leg and udder traits).
Due to this, a strong improvement of longevity, health and production can be achieved.
How to understand gRZG?
- Germany, Luxembourg and Austria have a joint evaluation for relative breeding values including RZG/gRZG for bulls and females of six dairy breeds (Holstein Friesian, Red Holstein, Angler/Red-Dairy-Cattle, German Friesians, German red&white Dual Purpose, Jersey) with an average of 100 and a standard deviation of 12 (base: all 4-6 year old cows within breed, shifted yearly).
- 95% of the animals within breed have breeding values between 76 and 124.
- This means that proofs over 124 represent the top 2.5% of the breed
Who is responsible for estimation and publication of breeding values?
vit is responsible for genetic evaluation (classical, genomics) for 59 traits for dairy breeds from Germany, Luxembourg and Austria. Besides all Interbull converted standard traits 13 health traits (udder health, claw health, reproductive health, metabolic stability), young stock survival and a robot index are included. Official genomic breeding values are calculated on a weekly base and results are published every Tuesday by vit for new animals. The breeding values of all animals are updated three times a year.
Where do you search for the gRZG of a specific sire?
All official breeding values for all national and by Interbull converted AI bulls can be found in the database on the vit homepage (bull database – international & German bulls) including search and selection functions. Official breed toplists are provided, too.