Prevalence of tail injuries in German Dairy cows

Objectives
Tail injuries and pathological alterations have been reported in many species. In cattle, they were investigated
mainly in fattening bulls and feedlot cattle. In dairy cows high prevalences for different tail alterations were
found. However, aetiology and pathogenesis of this health trait are still unclear and need further investigation.
Out of 4443 phenotypes of different tail alterations we assorted seven groups common in dairy cows: 1. very
tip of the tail , 2. ring-like, 3. scurf, 4. swelling, 5. thinning, 6. axis anomaly, and 7. verruca-like mass. The
objective of this study was to identify genomic regions that may influence the occurrence of different tail
alterations in dairy cows, which could be useful for a potential implementation of a genomic selection tool for
more robust and healthy cows in the future.
Material and methods
Data collection started in December 2019 from a German 75 German Holstein (HOL) cows dairy herd. All cows were
examined every two weeks during six months regarding any kind of tail alterations. The findings were described and
photographed. Data analysis resulted in seven different kinds of tail alterations: 1. very tip of the tail, 2. ring-like, 3. scurf,
4. swelling, 5. thinning, 6. axis anomalies, and 7. verruca-like mass.
Hereinafter, prevalences for the observed tail alterations were calculated based on monthly data collection from five
different dairy herds: 3 HOL herds, counting average herd sizes of 75, 300, and 1300, respectively; 2 German Fleckvieh
(FV) herds, counting 60 cows, each. All cows were housed in free stall barns with conventional (HOL, FV) or automatic
milking systems (FV).
In total, 4443 Dairy Cows' Tail Scores were recorded. Data preparation and analysis were performed using R version
4.1.2. Prevalences for tail alterations were calculated by dividing the number of observations within by the total number of
observations of each kind of tail alteration and was given in percent. For calculating the total prevalence per breed and
farm, the occurrence of at least one tail alteration counted as an observation, was divided by the total number of cows
under investigation and given in percent.
Results
The overall prevalence for any kind of tail alteration was 88% in German Holstein and 99% in Fleckvieh cows; it varied
between farms from 74% to 99%. Prevalences for HOL and FV regarding alterations of the very tip of the tail were 26%
and 71%, ring-like alterations 24% and 30%, swelling 26% and 42%, scurf 55% and 60%, thinning combined with axis
anomalies 16% and 21%, and verruca-like mass 10% and 21%, respectively. Number per tail ranged for ring-like
alterations and thinning/axis anomalies from 1 to 5 and for verruca-like mass from 1 to 3.
Conclusions
During this study, high prevalences for different tail alterations in HOL and FV dairy cows were found out. The grouping of
different alterations as described above can be useful to phenotype tail alterations in dairy cows. However, further
investigations regarding pathogenesis, aetiology, and genetics of the observed alterations in dairy cows' tails are needed
to understand their origin and impact on animal health and welfare.
Funding
This research was funded by the Tönnies Forschung, Rheda, Germany.