Heat stress and cow factors affect bacteria shedding pattern from naturally infected mammary gland quarters in dairy cattle
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Heat stress and cow factors affect bacteria shedding pattern from naturally infected mammary gland quarters in dairy cattle. / Hamel, Johannes; Zhang, Yanchao; Wente, Nicole; Krömker, Volker.
In: Journal of Dairy Science, Vol. 104, No. 1, 2021, p. 786-794.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Heat stress and cow factors affect bacteria shedding pattern from naturally infected mammary gland quarters in dairy cattle
AU - Hamel, Johannes
AU - Zhang, Yanchao
AU - Wente, Nicole
AU - Krömker, Volker
PY - 2021
Y1 - 2021
N2 - Mastitis-causing pathogens are shed from infected mammary gland quarters and thus contribute to an increased risk of new intramammary infections. The objective of the current study was to investigate the shedding characteristics of various mastitis-causing pathogens and associated animal-specific (somatic cell score and parity) and environmental (heat stress) factors. In a longitudinal study, infected udder quarters were sampled consecutively on 5 dairy farms in Germany. To capture climatic factors, temperature-humidity index (THI) was calculated. In the laboratory analysis, the pathogens and their counts in the milk samples were determined. A generalized linear mixed model with gamma link was used to evaluate the factors influencing pathogen-shedding characteristics. The variables somatic cell count, pathogen, parity, and THI had significant influence on pathogen shedding. Staphylococci were shed in lower values than streptococci. The pathogen shedding from mammary gland quarters with intramammary infections was higher in the first and second lactation than in higher lactations. Exceeding the THI threshold 60 resulted in higher pathogen counts on the same day. This was only caused by the pathogens yeasts and Streptococcus uberis. Possible mechanisms causing differences in pathogen shedding are changes in the counts due to influenced milk quantities, better growth conditions at higher temperatures, or altered immunological reactions. The mechanisms often remain speculative and require further investigation. The study underlines the contribution of cows with high somatic cell counts regarding the transmission of mastitis pathogens within a herd. Furthermore, it becomes clear that heat stress in Germany influences udder health and that prevention measures are useful.
AB - Mastitis-causing pathogens are shed from infected mammary gland quarters and thus contribute to an increased risk of new intramammary infections. The objective of the current study was to investigate the shedding characteristics of various mastitis-causing pathogens and associated animal-specific (somatic cell score and parity) and environmental (heat stress) factors. In a longitudinal study, infected udder quarters were sampled consecutively on 5 dairy farms in Germany. To capture climatic factors, temperature-humidity index (THI) was calculated. In the laboratory analysis, the pathogens and their counts in the milk samples were determined. A generalized linear mixed model with gamma link was used to evaluate the factors influencing pathogen-shedding characteristics. The variables somatic cell count, pathogen, parity, and THI had significant influence on pathogen shedding. Staphylococci were shed in lower values than streptococci. The pathogen shedding from mammary gland quarters with intramammary infections was higher in the first and second lactation than in higher lactations. Exceeding the THI threshold 60 resulted in higher pathogen counts on the same day. This was only caused by the pathogens yeasts and Streptococcus uberis. Possible mechanisms causing differences in pathogen shedding are changes in the counts due to influenced milk quantities, better growth conditions at higher temperatures, or altered immunological reactions. The mechanisms often remain speculative and require further investigation. The study underlines the contribution of cows with high somatic cell counts regarding the transmission of mastitis pathogens within a herd. Furthermore, it becomes clear that heat stress in Germany influences udder health and that prevention measures are useful.
KW - bacteria shedding
KW - heat stress
KW - intramammary infection
KW - somatic cell count
U2 - 10.3168/jds.2020-19091
DO - 10.3168/jds.2020-19091
M3 - Journal article
C2 - 33189273
AN - SCOPUS:85096019808
VL - 104
SP - 786
EP - 794
JO - Journal of Dairy Science
JF - Journal of Dairy Science
SN - 0022-0302
IS - 1
ER -
ID: 251912083