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Table 1 Production, SCC, infection status, and Staphylococcus aureus isolation events for treatment and control group

From: Effect of lactation therapy on Staphylococcus aureus transmission dynamics in two commercial dairy herds

Herd Pen Monthly average number lactating cows Monthly average milk production (kg) Monthly average SCC (cells/ml x 1000) Total Quarter Days at risk for new IMI1 Total Quarter Days Infected2 Number S. aureus isolates (# quarters/# cows)
        IMI associated isolates3 incidental isolates3
1 treatment 95 31.4 419 129984 1335 80(21/20) 15(13/11)
  control 98 32.7 401 130254 2479 137(25/21) 22(20/17)
  whole herd4 319 32.7 404    221(50/45) 37(33/28)
2 treatment 91 42.3 292 125241 1345 58(11/9) 2(2/2)
  control 89 41.4 296 116295 14 1(1/1) 0
  whole herd 346 35.0 298    68(21/16) 4(4/4)
  1. 1 Sum of individual quarter days uninfected at risk for new intramammary infection (IMI).
  2. 2 Sum of individual quarter days infected based on midpoint estimates of IMI start and stop dates [17].
  3. 3 IMI status based on definitions of Zadoks et al. [12]; incidental isolates are those not meeting IMI criteria.
  4. 4 Whole herd totals include all lactating cows during study period, (cows that entered treatment and control groups, plus cows never housed with these groups); number of isolates obtained from whole herd exceeds sum of treatment and control pens as 13 IMI isolates and 2 incidental isolates were obtained from milk samples collected from cows sampled at the start of a lactation and either the IMI cured prior to entry into a study pen or the cow did not enter a study pen during the course of the trial.