First insights into possible risk factors for tail tip lesions in dairy cows

Objectives

Although inflammation and necrosis of the tail tip has been a well-known problem in fattening cattle for several decades, the etiology of the disease is not fully understood, yet. While some authors hold husbandry conditions such as limited space allotment or slatted concrete floors responsible for the occurrence of tail lesions, other studies point towards a connection with rumen acidosis. Furthermore, tail necrosis has also been described in the context of mycotoxin intake, which leads to vasoconstriction, finally resulting in ischemia. In dairy cows, we observed lesions of the tail, which resemble those described in housed fattening cattle, although husbandry conditions of dairy cows differ from those of fattening cattle. In order to identify possible risk factors, the aim of this study was to investigate whether there are associations between the occurrence of tail tip lesions and selected health and performance parameters in dairy cows.

Material and methods

For this purpose, we monitored the course of the lesions over 10 months in a German dairy herd consistig of 1,300 cows. The cows were housed on slatted rubber floor in a loose housing system. The cubicles either contained straw manure bedding or were covered with waterbed mattresses. Manure was removed by an automatic scraper system. N = 213 cows that calved within a predetermined period of 2 months were selected for the study to ensure that all cows were at a similar stage of lactation. Number of lactation varied between cows, ranging from one to seven. The sample consisted of 89% Holstein Friesian cows, 10% crossbreds and 1% Brown Swiss cows. Examinations took place at every milk performance testing, starting after calving. One single person assessed tail tip lesions, locomotion score and body condition score of the cows. Number of lactation, days in milk, and data from milk performance testing including milk yield, milk fat:protein ratio and somatic cell count were used for further analysis. The frequencies of the individual tail lesions were calculated by dividing the number of each lesion by the number of all observed lesions. Data were processed using Rstudio version 2021.09.2. Chi²-test and a mixed model procedure were performed for statistical analysis of possible risk factors for the different lesions.

Results

Over the course of the examination period, every cow was affected by one or several lesions at least once. The examination of n = 213 cows resulted in 4,123 observations. We were able to observe all of the previously described lesions, with varying frequencies, namely: lesions at the very tip of the tail: 8.2 %, annular lesions: 8.5 %, hyperkeratosis: 52.0 %, swelling: 10.7 %, axis deviation: 9.2 %, thinning: 0.2 % and fibroma: 3.7 %. The frequency of tails without any visible lesion was 7.5 %. Regarding the results of the Chi²-test, with the exception of the somatic cell count, all parameters included in this study had a significant influence on at least one lesion. Days in milk significantly influenced all lesions (p < 0.01 or p < 0.001) except of thinnings of the tail. Lactation number had a significant impact on the occurrence of hyperkeratosis (p < 0.05), swellings (p < 0.001), axis deviations (p < 0.01) and fibromas (p < 0.001). Hyperkeratosis and axis deviations were furthermore influenced by milk yield (p < 0.05 and p < 0.001, respectively). Milk fat:protein ratio had a significant impact on hyperkeratosis (p < 0.05) and thinning (p < 0.001). Locomotion score significantly influenced annular lesions (p < 0.05) and axis deviations (p < 0.05), whereas body condition score had a significant impact on the occurrence of swellings (p < 0.001).

Conclusions

Our results demonstrate that there are multiple associations between tail tip lesions and different health- and performance parameters such as milk yield, locomotion score and body condition score. Based on our results, we conclude that the formation and development of tail tip lesions is a complex, presumably multi-factorial process. Further research is required to examine the individual risk factors in more detail.

Funding

Parts of this research were funded by the Tönnies Forschung, Rheda, Germany.