Production, Management, and the Environment 1

摘要

Compost bedded pack barns utilize composting methods which requiremicrobial growth. In turn, this may increase the exposure of mastitis-causingpathogens to the teats of dairy cows. Our objective was to determinethe relationship between environmental effects and cow bacteria countsover time in transition cows. Twenty-six Holstein cows (11 primiparous,15 multiparous) were enrolled in an observational study from December2018 to May 2019. Quarter teat skin swabs, teat end swabs and milksamples were aseptically collected from every cow 14 d before expectedcalving date, 3 d postpartum, and biweekly through 60 ± 7 DIM. Beddingsamples were collected weekly (n = 396). Teat skin swabs, teat end swabsand bedding samples underwent microbial analysis to enumerate environmentalmicrobes. Bedding samples were analyzed for moisture, C:N ratioand pH. Milk samples were cultured for presence or absence of bacteria.Pearson correlations determined associations among cow variables. Linearmixed models determined effect of stages in the transition period (exptweek) and environmental factors on cow bacteria counts. Teat skin totalbacteria 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 coliformand Staphylococcus spp. (Staph.) counts changed (P < 0.05) frompre- to postpartum, where LS Means of coliforms increased from 2.09 to2.75 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 coliformsincreased from 1.19 to 1.46 log10 cfu/g and Staph. counts decreasedfrom 4.08 to 2.63 log10 cfu/g. Bedding moisture was the only factor thatsignificantly affected teat skin bacteria counts. As moisture increased by1%, teat skin TBC decreased by 1.06 (0.59; SE) log10 cfu/g. We concludethat environmental factors over time do not influence teat microbial population.Calving time may be a larger contributing factor to teat microbiome.