Machine milking-induced alterations of teat tissue may impair local defense mechanisms and increase the risk of new intramammary infections. The objective of the current study was to assess the influence of short-term and long-term alterations of teat tissue and infectious status of the udder quarter on the risk of naturally occurring new intramammary infections, inflammatory responses, and mastitis. Short-term and long-term changes in teat condition of right udder quarters of 135 cows of a commercial dairy farm in Saxony-Anhalt, Germany, were recorded monthly for 10 mo using simple classification schemes. Quarter milk samples were collected from all examined quarters at each farm visit. Bacteriological culture results and somatic cell counts of quarter milk samples were used to determine new inflammatory responses (increase from ≤100,000 cells/mL to >100,000 cells/mL between 2 samples), new infections (detection of a pathogen from a quarter that was free of the same pathogen at the preceding sampling), and new mastitis (combination of new inflammatory response and new infection). Separate Poisson mixed models for new inflammatory responses, new infections, and new mastitis caused by specific pathogens or groups of pathogens (contagious, environmental, major, minor, or any) were used to estimate risk ratios and 95% confidence intervals. Data preparation and parameter estimation were performed using the open source statistical analysis software R. We observed no effect of any variable describing teat condition on the risk of new intramammary infections, inflammatory responses, or mastitis. Intramammary infections of the same udder quarter in the preceding month did not affect risk either.
Short and long-term changes in teat condition mainly caused by machine milking may affect the udder health of lactating dairy cattle. The objective was to investigate the prevalence of teat end hyperkeratosis scores in lactating dairy cattle in Germany and to determine associations between animal variables and teat end hyperkeratosis. The study was conducted in 15 German high-yielding dairy herds. On dairy farms teat size, teat shape, teat end shape and changes in teat condition (edema, teat skin colour, teat end hyperkeratosis) were recorded. In total, 4,022 animals of the breed German Holstein were included into the present study. For both front and rear teats associations between teat end hyperkeratosis and lactation number, teat length, teat diameter and teat end shape were found. Further research is needed to reduce the prevalence of teat end hyperkeratosis in high-yielding dairy herds and to improve the teat condition.
Zusammenfassung:In der wissenschaftlichen Literatur lassen sich Hinweise auf Zusammenhänge zwischen Zitzenkondition und Eutergesundheit finden. Besonders für akute Zitzenkonditionsstörungen ist jedoch der Nachweis einer logischen Kausalkette schwierig, da Mastitiden eine multifaktorielle Genese besitzen. In den hier vorwiegend dargestellten Feldstudien kann der Einfluss anderer Faktoren auf den Gesundheitszustand der Milchdrüse nicht ausgeschlossen werden. Dennoch erscheint es nachvollziehbar, dass Störungen der Mikrozirkulation die lokale Abwehr negativ beeinflussen, indem sie die Rekrutierung von Abwehrzellen behindern, den Verschluss des Zitzenkanals verzögern oder den Ausmelkgrad der Drüsenviertel verschlechtern. Longitudinalstudien, die im Hinblick auf die wesentlichen Einflussgrößen standardisiert sind, verfügen über mehr Aussagekraft. Das Mastitisrisiko für ein Drüsenviertel ist erhöht, wenn die Zitze einer schlechteren Hyperkeratoseklasse zugeordnet werden kann. Solche Zitzen lassen sich schwerer reinigen, begünstigen die Besiedlung mit euterpathogenen Mikroorganismen und weisen einen verzögerten Zitzenkanalschluss auf. Die vorliegende Arbeit versucht in Form einer Literaturübersicht den Kenntnisstand zur Bedeutung einer gestörten Integrität der Zitzenkanalschleimhaut, des Zitzengewebes oder der Zitzenhaut auf die Entstehung von Mastitiden zu beschreiben.
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