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Case study: Do low-risk cows in a data-driven selective dry-cow program remain low risk at a subsequent dry-off?

A. K. Vasquez



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Case study: Do low-risk cows in a data-driven selective dry-cow program remain low risk at a subsequent dry-off?
A. K. Vasquez*1,2, M. L�pez Benavides2, M. J. Thomas3, D. V. Nydam1. 1Cornell University Ithaca, NY, 2DeLaval Manufacturing Kansas City, MO, 3Dairy Health & Management Services Lowville, NY.

A data-driven, selective dry-cow therapy algorithm has been used often in trials by the authors and has been implemented by US dairy producers to target prudent use of antimicrobials. This case report retrospectively evaluated the recurrence, characteristics, and culture results of cows from a NY dairy that were identified as “low risk” by the algorithm during the 2nd year of using the program. All cows eligible for dry-off had the opportunity to be enrolled from April 2018 to Oct 2018 and again from May 2019 to Aug 2019. “Low risk (LR)” cows (cows that likely will not benefit from antibiotics) were identified as having all of the following: < 200k cells/mL at last test day before dry-off, an average somatic cell count <200k cells/mL on the last 3 test days, no signs of mastitis at dry-off, and no more than 1 clinical mastitis event in the current lactation. Quarter-level milk samples were aseptically retrieved at dry-off during both periods and were submitted for diagnostic aerobic culture and MALDI-TOF following National Mastitis Council guidelines. Of the LR cows (>1st lactation) dried off during the second evaluation period (n = 166), 120 (75%) were identified as being present in the first dry-off period. The distribution by lactation for 2nd, 3rd, and greater than 3rd was 57%, 25%, and 18%. The majority of cows were LR during both periods (n = 101, 84.2%), while the remaining 19 were identified as high risk (HR) during the first period. Of the functional quarters (n = 469) from the 120 cows, bacteriology indicated that 77% were negative at dry-off for both periods. The common remaining culture results were quarters with Staphylococcus species (NAS) at the first sampling period and culture negative at the second (9%), contaminated at the first and negative at the second (3%), and culture negative at the first and NAS at the second (3%). For the 19 cows that were HR during the first dry-off period, 13/19 (68%) had a pathogen in at least 1 quarter during the first period. Five of 13 were major mastitis pathogens. This study indicated that LR cows remain consistent in their algorithm assignment over the course of 2 dry-offs and most quarters remain culture negative.

Keywords: selective dry-cow therapy.