Abstract #LB3
Section: Late-Breaking Original Research Abstracts
Session: Late-Breaking Original Research Session
Format: Oral
Day/Time: Sunday 3:30 PM–3:45 PM
Location: Room 205
Session: Late-Breaking Original Research Session
Format: Oral
Day/Time: Sunday 3:30 PM–3:45 PM
Location: Room 205
# LB3
Selective dry cow therapy on US dairy farms: Impact on udder health and productivity.
S. Rowe*1, S. Godden1, E. Royster1, J. Timmerman1, D. Nydam2, A. Vasquez2, P. Gorden3, A. Lago4, 1University of Minnesota, Saint Paul, MN, USA, 2Cornell University, Ithaca, NY, USA, 3Iowa State University, Ames, IA, USA, 4DairyExperts, Tulare, CA, USA.
Key Words: selective dry cow therapy, on-farm culture, algorithm
Selective dry cow therapy on US dairy farms: Impact on udder health and productivity.
S. Rowe*1, S. Godden1, E. Royster1, J. Timmerman1, D. Nydam2, A. Vasquez2, P. Gorden3, A. Lago4, 1University of Minnesota, Saint Paul, MN, USA, 2Cornell University, Ithaca, NY, USA, 3Iowa State University, Ames, IA, USA, 4DairyExperts, Tulare, CA, USA.
Culture- and algorithm-guided selective dry cow therapy (SDCT) programs were each compared with blanket dry cow therapy (BDCT) in a clinical trial for the following outcomes: antibiotic (ABX) use at dry-off; risk of new and cured infections (IMI) during the dry period; 120-d clinical mastitis (CM) and culling risks; milk yield and somatic cell count (SCC) in the first 120 d in milk. Seven herds were recruited from 4 study sites (CA, IA, MN, and NY). Cows (n = 1,275) were randomly allocated to BDCT, Culture-SDCT, and Algorithm-SDCT. All quarters of the Blanket group were treated with intramammary ABX. Quarters of Culture cows received ABX if any growth was observed after milk culture using the MN Easy 4Cast plate. Algorithm cows received ABX in all quarters if they met any of the following criteria: ≥ 2 cases of CM during lactation, CM during the 14 d before dry-off, or any test day SCC >200,000 cells/ml during lactation. All quarters were treated with an internal teat sealant. Risk differences (RD), Hazard ratios (HR) and adjusted means were estimated using marginal standardization, Cox proportional hazards and linear mixed models, respectively. Quarter-level ABX use was reduced by 55% in each SDCT group. IMI cure risk was similar in Blanket (89.8%), Culture (90.0%, RD = +0.2%, 95%CI: −4.4, 4.7%) and Algorithm (90.4%, RD = +0.6%, 95%CI: −3.9, 5.2%) quarters. New IMI risk was similar in Blanket (15.1%), Culture (15.3%, RD = +0.2%, 95%CI: −2.5, 2.9%) and Algorithm (14.9%, RD = −0.2%, 95%CI: −2.9, 2.5%) quarters. CM incidence was similar for Blanket (14.5%), Culture (12.2%, HR = 0.82, 95%CI: 0.6–1.2), and Algorithm (12.2%, HR = 0.82, 95%CI: 0.6, 1.1) cows. Risk of culling was similar for Blanket (10.8%), Culture (9.8%, HR = 0.89, 95%CI: 0.6, 1.3) and Algorithm (10.6%, HR = 0.98, 95%CI: 0.7, 1.4) cows. Adjusted geometric mean SCC was similar for Blanket (55, 95%CI: 47, 65), Culture (57, 95% CI: 49, 68), and Algorithm (59, 95%CI: 50, 69) cows. Adjusted average daily milk yield (kg/day) was: Blanket (48.6, 95%CI: 46.2, 51.1), Culture (48.6, 95%CI: 46.2, 51.1), and Algorithm (47.8, 95% CI: 45.3, 50.2). SDCT successfully reduced ABX use by 55%, without causing negative effects on health and productivity.
Key Words: selective dry cow therapy, on-farm culture, algorithm
