No abstract

Results suggest that for dairy cattle with an IMI late in the lactation period, intramammary administration of cloxacillin at the end of lactation followed by insertion of an ITS enhanced protection against development of new IMIs, compared with use of cloxacillin alone.

Within-cow half-udder comparison trials are valid for antimicrobial trials in nonlactating cows, although transfer of antimicrobials does occur in trace concentrations. Ipsilateral or diagonal-contralateral treatment designs perform similarly. This type of design is economical for researchers, although care must be taken to account for within-cow clustering of mammary gland quarter data.

The objective of this study was to determine if an internal teat sealer used in addition to dry-cow antibiotics would have a beneficial effect on the elimination of intramammary pathogens during the dry period. In total, data from 425 culture-positive quarters from 270 Holstein-Friesian dairy cows were utilized in this trial. Milk samples were collected aseptically two weeks prior to the anticipated dry-off date, on the dry-off date and again at 1-8 days-in-milk. Infected quarters were randomly assigned to treatment with both an internal teat sealer and a dry-cow antibiotic, or a dry-cow antibiotic alone. Quarters were defined as cured if the pathogen(s) isolated in the dry-off sample were not isolated in the postpartum sample. There was no difference in overall bacteriological cure between the two treatment groups, internal teat sealer and dry-cow antibiotic versus dry-cow antibiotic alone. Similarly, no significant differences were observed for cure of either major or minor pathogen infections.