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The objective of this prospective study was a blinded comparison of three methods for the identification of bacteria isolated on Columbia blood agar from milk samples of dairy cows. Basic biochemical testing, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and 16S rRNA partial genome sequence analysis were compared for bacterial identification to the genus or species level. Milk samples submitted from a commercial dairy farm from recently calved cows or clinical mastitis cases were cultured, and 181 isolates were identified by biochemical testing, MALDI-TOF MS, and 16S rRNA sequence analysis (179 isolates; 2 isolates could not be recovered from storage). For Staphylococcus aureus and Escherichia coli , agreement was determined at the species level. For other microbes, agreement was determined at the genus level or at the group level for streptococcus-like organisms. The positive agreement among all 3 diagnostic methods was 94%, with 95% to 98% between each pair of methods. The overall (including negative agreement) agreement among all 3 methods ranged from 97% to 100%. MALDI-TOF MS is becoming more commonplace for the genus- and/or species-level identification of bacteria isolated from milk samples and, in some laboratories, has replaced conventional biochemical methods. The results of the present study suggest that when identifying pathogens at the genus or group level, conventional culture followed up with either secondary biochemical testing or MALDI-TOF MS is of practical value. For purposes of milk quality and udder health monitoring or research, any of the 3 methods is a valuable tool for genus-level identification of bacteria isolated from dairy cow milk., (Copyright © 2019 American Society for Microbiology.)

The aim of this field study was to compare the efficacy and cost of 2 commercially available oral rehydration therapy (ORT) solutions in treating dairy calves with naturally acquired diarrhea. A total of 1,349 newborn Holstein-Friesian calves were prospectively enrolled in the study. Calves were housed in individual hutches and fed a mixture of pasteurized hospital milk and an all-milk protein milk replacer twice per day. Calves were monitored twice each day from d 2 of life until 30 d of age for the presence or absence of diarrhea, and were assigned a fecal score and a hydration score at each examination. Calves that developed mild to severe diarrhea that did not need intravenous fluids and did not have clinical evidence of concurrent disease (n = 360) were assigned randomly to receive 1 of 2 commercial ORT solutions: a hypertonic alkalinizing ORT containing lecithin-coated citrus fibers (Diaque, group D, n = 180; Boehringer Ingelheim, Ingelheim, Germany), and an isotonic nonalkalinizing ORT (RE-SORB, group R, n = 180; Pfizer Animal Health, New York, NY) for 2 to 8d; the duration of treatment depended on whether diarrhea was still present. No significant differences were observed in mortality rates or treatment failure rates between the 2 treatment groups. Fecal consistency returned to normal more quickly in group D calves than in group R calves; consequently, group D calves were treated for 1d less than were group R calves. The increase in body weight after 4d of treatment was larger in group D than in group R. The average daily gain from birth to weaning in calves that did not develop concurrent disease (such as pneumonia) during the study period tended to be higher in group D calves (0.53±0.11 kg/d) than in group R calves (0.51±0.09 kg/d). The smaller number of treatments at a lower cost per treatment produced a cost advantage of $4.82 per treated calf in group D calves compared with group R calves. Our findings support the concept that milk should continue to be fed to diarrheic calves that are being administered an ORT solution in order to maintain growth., (Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Objective: To estimate seroprevalence of Mycobacterium avium subsp paratuberculosis (MAP) infection among adult dairy cows in Colorado and determine herd-level factors associated with the risk that individual cows would be seropositive., Design: Cross-sectional observational study., Animals: 10,280 adult (> or = 2 years old) dairy cows in 15 herds in Colorado., Procedure: Serum samples were tested with a commercial ELISA. A herd was considered to be infected with MAP if results of mycobacterial culture of > or = 1 individual cow fecal sample were positive or if > or = 1 culled cow had histologic evidence of MAP infection., Results: 424 of the 10,280 (4.12%) cows were seropositive. Within-herd prevalence of seropositive cows ranged from 0% to 7.82% (mean, 2.6%). Infection was confirmed in 11 dairies. Cows in herds that had imported > or = 8% of their current herd size annually during the preceding 5 years were 3.28 times as likely to be seropositive as were cows in herds that imported < 8%. Cows in herds with > or = 600 lactating cows were 3.12 times as likely to be seropositive as were cows in herds with < 600 lactating cows. Cows in herds with a history of clinical signs of MAP infection were 2.27 times as likely to be seropositive as were cows in herds without clinical signs., Conclusions and Clinical Relevance: Annual importation rate, herd size, and whether cows in the herd had clinical signs typical of MAP infection were associated with the risk that individual cows would be seropositive for MAP infection.