Until 1996, Holstein cows in Germany were bred exclusively for milk production. Thanks to these milk-orientated genetics, good farm and feed management and increasing scientific knowledge, milk production in Germany has risen to a considerable level in recent years. However, the average productive life is still unsatisfactory. This was the reason for focussing breeding in dairy farming more on improving animal health and other secondary traits.
Since April 1996, conformation (as an indicator of hoof and udder health), cell count (for udder health), productive life, fertility and calving behaviour (for calving ease) have been integrated proportionally into the overall breeding value.
Development of the milk yield trait
Since 1996, the prioritisation of the trait milk yield in German Holstein breeding has fallen from 100 % to 45 % (Figure 1). The introduction of an economic breeding value (RZ€) in August 2020 and a new overall breeding value (RZG) in April 2021 will further strengthen this trend.
RZHealth as overall breeding value Health
In 2005, the digital collection of dairy cow health data began with a test herd project, which led to the establishment of the udder health (2015) and hoof health (2016) breeding values for the first time in Germany. Through the nationwide genotyping of more than 200,000 cows and comparison with health data, breeding values for the inheritance of udder, claw and limb health as well as metabolic and reproductive health have been available throughout Germany since April 2019, which are weighted in the RZGesund as an overall breeding value for health according to their economic importance. This replaced the RZFit breeding value, which had existed since 2010 and related to the ability of a breeding bull to pass on desirable fitness traits (functional traits) to daughter cows.
The overall breeding value RZHealth comprises a total of 13 individual traits from four trait complexes:
- RZEuterfit comprises traits for clinical & subclinical mastitis,
- RZClaw is made up of traits for claw diseases (claw ulcers, panaritium, roe deer, limax, white line disease & Mortellaro), whereby Mortellaro has its own sub-breeding value with DDControl,
- RZMetabol comprises traits of metabolic diseases (abomasal displacement, milk fever, ketosis),
- RZRepro includes characteristics of reproductive disorders (cycle disorders, endometritis, postpartum retention).
New advances in biotechnology and data processing make it possible to determine early and accurate breeding values for late traits such as longevity through comprehensive typing of dairy cows.
Since August 2020, there has been a new weighting of the RZGesund.
The following figures (2 and 3) illustrate the changes in the weighting of individual areas in RZGesund.
Breeding value useful life (RZN)
Since April 2018, the breeding value for longevity (RZN) has been estimated. From the first calving to the fourth calving, the resulting three lactations are each divided into three sections. This results in survival information as early as the 50th day of the first lactation, which marks the end of the first section. This means that all bulls with the first daughter-based breeding values for milk yield and cell counts also receive longevity breeding values based on daughter information.
New introduction of the breeding value for calf fitness (RZKälberfit)
In addition, a new breeding value relating to the calves' rearing period (RZKälberfit) was introduced in August 2019. This describes the genetically determined ability to survive the rearing period from day 2 to 15 months of age. However, the breeding value relates exclusively to female calves.
Further information
Description of the breeding value estimation for all estimated traits in the dairy cattle breeds for which vit is commissioned with the breeding value estimation:
www.vit.de/fileadmin/DE/Zuchtwertschaetzung/Zws_Bes_deu.pdf
Information from the Rinderallianz on RZGesund:
rinderallianz.de/holstein/rzgesund/
Information from the Bundesverband Rind und Schwein e.V. on breeding value estimation:
www.rind-schwein.de/brs-rind/brs-zuchtwertschaetzung-2.html
RZ - Breeding correctly with the health breeding values of German Holstein breeding:
richtigzuechten.de/allgemein/richtigzuechten-rzgesund.html