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Environmental effects on teat microbial population of transition dairy cows housed in compost bedded pack barns.

T. L. France



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Environmental effects on teat microbial population of transition dairy cows housed in compost bedded pack barns.
T. L. France*, J. C. H. Costa, M. C. Morgan. University of Kentucky Lexington, KY.

Compost bedded pack barns utilize composting methods which require microbial growth. In turn, this may increase the exposure of mastitis-causing pathogens to the teats of dairy cows. Our objective was to determine the relationship between environmental effects and cow bacteria counts over time in transition cows. Twenty-six Holstein cows (11 primiparous, 15 multiparous) were enrolled in an observational study from December 2018 to May 2019. Quarter teat skin swabs, teat end swabs and milk samples were aseptically collected from every cow 14 d before expected calving date, 3 d postpartum, and biweekly through 60 � 7 DIM. Bedding samples were collected weekly (n = 396). Teat skin swabs, teat end swabs and bedding samples underwent microbial analysis to enumerate environmental microbes. Bedding samples were analyzed for moisture, C:N ratio and pH. Milk samples were cultured for presence or absence of bacteria. Pearson correlations determined associations among cow variables. Linear mixed models determined effect of stages in the transition period (expt week) and environmental factors on cow bacteria counts. Teat skin total bacteria count (TBC) had a moderate relationship with teat end TBC (r = 0.42; P < 0.001). Teat end TBC had a weak relationship with milk TBC (r = 0.18; P < 0.001). Expt week affected all cow bacteria counts (P < 0.05). Parity affected milk TBC and teat skin counts (P < 0.05). Teat skin coliform and Staphylococcus spp. (Staph.) counts changed (P < 0.05) from pre- to postpartum, where LS Means of coliforms increased from 2.09 to 2.75 log10 cfu/g and Staph. counts decreased from 5.67 to 4.53 log10 cfu/g. Similar results were found for teat end counts, where LS means of coliforms increased from 1.19 to 1.46 log10 cfu/g and Staph. counts decreased from 4.08 to 2.63 log10 cfu/g. Bedding moisture was the only factor that significantly affected teat skin bacteria counts. As moisture increased by 1%, teat skin TBC decreased by 1.06 (0.59; SE) log10 cfu/g. We conclude that environmental factors over time do not influence teat microbial population. Calving time may be a larger contributing factor to teat microbiome.

Keywords: bacteria count, mastitis.

Biography: Tanya France received her BS in Animal Science from Iowa State University in 2017 and her MS in Animal and Food Science at the University of Kentucky in January 2020. Her MS focused on compost bedded pack barn management, bedding microbiology, and teat exposure in transition dairy cows. Tanya is currently a first year PhD student under Dr. Joseph McFadden at Cornell University. Her research will focus on fatty acid and choline nutrition and metabolism, and their interactions with immunity in transition dairy cattle.