Residues of dry cow antimicrobials in colostrum and extended-spectrum and AmpC β-lactamaseproducing Escherichia coli in feces from young dairy calves.

The duration of excretion of dry cow antimicrobials is hard to predict and therefore the level of antimicrobial residues in colostrum can differ considerably between cows. The feeding of colostrum with antimicrobial residues to newborn calves may lead to antimicrobial resistance in calves. The aim of this study was to quantify the prevalence and residue level of dry cow antimicrobials in colostrum from dairy cows.

Postpartum excretion of internal teat sealant after selective dry cow treatment of dairy cows.

To comply with antibiotic restriction policies in the European Union, internal teat sealants (TS) are increasingly used at dry off (DO) in selective dry cow treatment protocols to maintain udder health. Postcalving TS residue attachment to milking equipment and associated cleaning difficulties is a reason some farmers stay away from blanket TS use. Our objective was therefore to improve insight into TS excretion visibility and to compare quantity, pattern, and presence versus absence of TS excretion postcalving between the typical 2 cow categories at DO: high (H)- and low (L)-SCC cows, treated with antibiotic (AB) plus TS (H-ABTS) or TS only (L-TS), respectively.

Prevalence of extended-spectrum and AmpC β-lactamase-producing Escherichia coli in young calves on Dutch dairy farms.

In young calves on dairy farms the animal prevalence of extended-spectrum and AmpC β-lactamase-producing Escherichia coli (ESBL/AmpC-EC) is significantly higher compared with the animal prevalence in young stock and dairy cows. Hitherto it was unknown at what age antimicrobial resistant bacteria appear for the first time in the gut of calves on dairy farms, and how long these infections persist. The aim of this study was to examine the prevalence of ESBL/AmpC-EC, the number of excreted ESBL/AmpC-EC (in cfu/g of feces), as well as the ESBL/AmpC genotypes in young dairy calves (0-21 d of age) and the variation of these parameters between calves of different ages.

Dynamics of Mycoplasma bovis in Dutch dairy herds during acute clinical outbreaks.

Mycoplasma bovis (M. bovis) can cause serious illness in cattle, presenting as arthritis and mastitis in dairy cows and pneumonia, arthritis and otitis media in calves. This study aimed to provide insight into the dynamics of M.