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D'Amico K, Neves RC, Grantz JM, Taechachokevivat N, Ueda A, Dorr A, Hubner A. A randomized, controlled trial examining quarter-level somatic cell count and culture-based selective dry cow therapy against blanket dry cow therapy on early lactation production outcomes. J Dairy Sci 2024; 107:7201-7210. [PMID: 38762106 DOI: 10.3168/jds.2023-24188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 03/30/2024] [Indexed: 05/20/2024]
Abstract
The objective of this study was to determine quarters requiring antimicrobial treatment using either a benchtop somatic cell counter or culture with gram-positive selective media and compare the outcomes in these cows to those receiving blanket dry cow therapy (BDCT) in a randomized, controlled trial. We evaluated 2 novel methods of identifying cows with intramammary infections followed by selective antimicrobial treatment at a commercial dairy farm to determine their usefulness in decreasing antibiotic usage during the dry period without significant detrimental effects on milk quality and production. Cows (n = 840) were randomly allocated to one of 3 groups (BDCT, gram-positive selective media culture-based selective dry cow therapy [C-SDCT], and somatic cell count-based SDCT [S-SDCT]) the day before dry-off, and quarter-level milk samples (QLMS) were collected. The QLMS from cows in the S-SDCT group were evaluated using the cell counter, and quarters were treated if SCC was ≥200,000 cells/mL, whereas the QLMS from cows in the C-SDCT group were cultured, and quarters were treated if the culture showed growth. All cows in the BDCT received antimicrobial therapy, and all cows received an internal teat sealant regardless of treatment group. Outcomes measured were first and second DHIA test SCC, milk production through 60 DIM, cows leaving the farm, clinical mastitis, and bacteriologic new infections in a subset of quarters. Cows in both SDCT groups had fewer antimicrobial treatments than cows in the BDCT group as was expected, and cows in the C-SDCT group had fewer treatments than those in the S-SDCT group. Cows in both SDCT groups had a higher linear score at the first DHIA test (BDCT: 1.8, S-SDCT: 2.2, C-SDCT: 2.2); however, we found no other differences between groups regarding any other outcomes measured. Although antimicrobial use was significantly reduced, farms should use caution in adopting the benchtop analyzer and the selective media described in this study as ways to identify infected cows for dry cow therapy because they may result in increased linear scores early in lactation.
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Affiliation(s)
- K D'Amico
- Department of Veterinary Clinical Sciences, Purdue University, West Lafayette, IN 47907
| | - R C Neves
- Department of Veterinary Clinical Sciences, Purdue University, West Lafayette, IN 47907
| | - J M Grantz
- Department of Veterinary Clinical Sciences, Purdue University, West Lafayette, IN 47907
| | - N Taechachokevivat
- Department of Veterinary Clinical Sciences, Purdue University, West Lafayette, IN 47907
| | - A Ueda
- Department of Veterinary Clinical Sciences, Purdue University, West Lafayette, IN 47907
| | - A Dorr
- Zoetis Animal Health, Florham Park, NJ 07932
| | - A Hubner
- Department of Veterinary Clinical Sciences, Purdue University, West Lafayette, IN 47907.
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2
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Le Page T, Ferchiou A, Dufour S, Kabera F, Dubuc J, Lhermie G, Raboisson D, Roy JP. Dairy farmer's income, working time, and antimicrobial use under different dry cow therapy protocols. J Dairy Sci 2024:S0022-0302(24)00933-0. [PMID: 38908700 DOI: 10.3168/jds.2023-24407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 05/28/2024] [Indexed: 06/24/2024]
Abstract
Mastitis is one of the most common diseases of dairy cattle. It has a high impact on farm economy, farmers' working time, and antimicrobial usage (AMU). Selective dry cow therapy (SDCT) is an effective means of reducing AMU without negatively affecting udder health. The objective of our study was to evaluate the impact of SDCT implementation on farmer's income, working time, and AMU, using a bioeconomic model. A stochastic dairy simulation model (DairyHealthSim) based on a weekly model was used to simulate herd dynamics, reproduction, milk production, culling decisions, health outcomes, and the management of health events. A specific module was developed for the simulation of quarter-level intramammary infection (IMI) acquisition and elimination during the lactation and dry-off periods, and 25 different farm settings were defined to represent herds with various udder health situations. We then defined 20 scenarios of SDCT by combining both the use of different thresholds of somatic cell count and milk bacteriology for treatment allocation and the use of internal teat sealant (ITS). All SDCT protocols had a low impact on farmer's income, and we identified some protocols with a positive farm gross margin (up to 15.83 CA$/dried- cow). We also found that adding an ITS to all cows led to greater economic gain. The application of SDCT had a low impact on farmers' working time, except when milk bacteriology was used for decision-making. Antimicrobial treatment to all cows above 200,000 cells/mL at last control, with the use of ITS on all cows, seems a good choice in most dairy farms. These findings could be used to convince farmers to adopt this strategy at dry-off.
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Affiliation(s)
- Thomas Le Page
- Faculty of veterinary medicine, Université de Montréal, Saint-Hyacinthe, J2S 2M2, Québec, Canada; Regroupement FRQNT Op+lait, Saint-Hyacinthe, J2S 2M2, Québec, Canada
| | - Ahmed Ferchiou
- CIRAD, UMR ASTRE, Montpellier, France, ASTRE, CIRAD, INRAE, Université de Montpellier, Montpellier, Université de Toulouse, ENVT, 31300 Toulouse, France
| | - Simon Dufour
- Faculty of veterinary medicine, Université de Montréal, Saint-Hyacinthe, J2S 2M2, Québec, Canada; Regroupement FRQNT Op+lait, Saint-Hyacinthe, J2S 2M2, Québec, Canada
| | - Fidèle Kabera
- Faculty of veterinary medicine, Université de Montréal, Saint-Hyacinthe, J2S 2M2, Québec, Canada
| | - Jocelyn Dubuc
- Faculty of veterinary medicine, Université de Montréal, Saint-Hyacinthe, J2S 2M2, Québec, Canada; Regroupement FRQNT Op+lait, Saint-Hyacinthe, J2S 2M2, Québec, Canada
| | - Guillaume Lhermie
- CIRAD, UMR ASTRE, Montpellier, France, ASTRE, CIRAD, INRAE, Université de Montpellier, Montpellier, Université de Toulouse, ENVT, 31300 Toulouse, France; Faculty of veterinary medicine, University of Calgary, Calgary, T2N 1N4, Alberta, Canada
| | - Didier Raboisson
- CIRAD, UMR ASTRE, Montpellier, France, ASTRE, CIRAD, INRAE, Université de Montpellier, Montpellier, Université de Toulouse, ENVT, 31300 Toulouse, France
| | - Jean-Philippe Roy
- Faculty of veterinary medicine, Université de Montréal, Saint-Hyacinthe, J2S 2M2, Québec, Canada; Regroupement FRQNT Op+lait, Saint-Hyacinthe, J2S 2M2, Québec, Canada.
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3
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Mondini S, Gislon G, Zucali M, Sandrucci A, Tamburini A, Bava L. Risk factors of high somatic cell count and differential somatic cells in early lactation associated with selective dry cow therapy. Animal 2023; 17:100982. [PMID: 37797494 DOI: 10.1016/j.animal.2023.100982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 08/30/2023] [Accepted: 09/01/2023] [Indexed: 10/07/2023] Open
Abstract
The routine use of intramammary antimicrobial products in all dairy cows at the beginning of the dry period is no longer allowed in European Union (EU) countries due to the new Regulation (EU) 2019/6 to reduce antimicrobial resistance. This study investigated the application of a selective dry cow therapy scheme and the risk factors of high individual milk somatic cell count (SCC) and individual neutrophil count in early lactation, as a response to the application of a selective dry cow therapy (SDCT) protocol. The study was carried out on three commercial farms, and a total of 243 lactating cows were monitored at the end of lactation and at the beginning of the next one, 91 of which were dried off without the use of antimicrobials (NoT) based on milk SCC, differential somatic cell count (DSCC), and the response of Vetscan DC-Q milk analyser, using a secret algorithm. The remaining 152 cows received antimicrobials (T). After calving, similar means were observed between the two treatment groups for SCC (4.8 vs 4.9 log10 cells/ml for T and NoT, respectively, P = 0.5) and total milk leucocyte count (TLC) (5 vs 5.1 log10 cells/ml for T and NoT, respectively, P = 0.7) in milk. However, the use of antimicrobials led to a lower DSCC (58 vs 64% for T and NoT, respectively, P = 0.01) and lower percentage of neutrophils (59 vs 64% for T and NoT, respectively, P = 0.05), although the levels of DSCC and percentage of neutrophils in cows dried off without antimicrobials remained lower than the risk threshold suggested by the international literature. A logistic regression was computed after the application of selective dry cow therapy to identify risk factors of high milk SCC (≥100 000 cells/mL) at the beginning of lactation. Increased milk SCC after calving was related to high SCC at the end of lactation and abandonment of antimicrobial therapy at dry-off. Moreover, the length of the dry period, milk protein content, and flank cleanliness in the last test day before dry-off were other factors in the logistic regression. Neutrophil counts at the beginning of the next lactation were affected by the same factors that influenced SCC, together with milk production, TLC, and macrophages on the last test day. The results obtained in these studied farms showed that selective dry cow therapy may be applied without adversely affecting the next lactation.
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Affiliation(s)
- S Mondini
- Department of Agricultural and Environmental Sciences, University of Milan, via Celoria 2, 20133 Milan, Italy
| | - G Gislon
- Department of Agricultural and Environmental Sciences, University of Milan, via Celoria 2, 20133 Milan, Italy
| | - M Zucali
- Department of Agricultural and Environmental Sciences, University of Milan, via Celoria 2, 20133 Milan, Italy
| | - A Sandrucci
- Department of Agricultural and Environmental Sciences, University of Milan, via Celoria 2, 20133 Milan, Italy
| | - A Tamburini
- Department of Agricultural and Environmental Sciences, University of Milan, via Celoria 2, 20133 Milan, Italy.
| | - L Bava
- Department of Agricultural and Environmental Sciences, University of Milan, via Celoria 2, 20133 Milan, Italy
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McCubbin KD, de Jong E, Brummelhuis CM, Bodaneze J, Biesheuvel M, Kelton DF, Uyama T, Dufour S, Sanchez J, Rizzo D, Léger D, Barkema HW. Antimicrobial and teat sealant use and selection criteria at dry-off on Canadian dairy farms. J Dairy Sci 2023; 106:7104-7116. [PMID: 37500435 DOI: 10.3168/jds.2022-23083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Accepted: 03/31/2023] [Indexed: 07/29/2023]
Abstract
Infections with antimicrobial resistant pathogens are a major threat to human and animal health worldwide. Further, reduction of livestock-associated antimicrobial use (AMU) is often identified as an area of focus. Selective dry cow therapy (DCT) warrants consideration as an important way to decrease AMU on Canadian dairy farms. In addition, teat sealants (TS) are a nonantimicrobial alternative for prevention of intramammary infection during the dry period. Therefore, objectives of this study were to determine how antimicrobials and TS are used at dry-off on Canadian dairy farms to determine selective DCT uptake and enacted selection protocols. It was expected that these data will provide a baseline understanding of DCT practices and highlight areas for future intervention to further reduce AMU. An observational study was conducted utilizing 2 in-person questionnaires conducted between July 2019 and September 2021 on 144 participating dairy farms in 5 Canadian provinces (British Columbia = 30, Alberta = 30, Ontario = 31, Québec = 29, and Nova Scotia = 24). Overall, 45 farms (31%) reported adopting selective DCT, 95 (66%) enacted blanket DCT, and 4 (3%) did not provide antimicrobial DCT. Farms enacting selective DCT had approximately 50% less intramammary antimicrobials used at dry-off compared with blanket DCT farms. Cow somatic cell count history was the most common criterion for selective DCT decision-making, followed by previous clinical mastitis history, bacteriological culture, and milk production. A slight majority of farms (56%) applied TS to all cows at dry-off, whereas 17 farms (12%) used TS selectively, and 46 farms (32%) did not use TS. Larger herds more often used TS, and farms with an automatic milking system more often used TS selectively than applied to all cows. Results highlighted the variability in antimicrobial treatment and TS use protocols at dry-off on Canadian dairy farms, and the potential for further antimicrobial reduction with increased adoption of selective DCT.
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Affiliation(s)
- Kayley D McCubbin
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1; One Health at UCalgary, University of Calgary, Calgary, AB, Canada T2N 4N1.
| | - Ellen de Jong
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Carmen M Brummelhuis
- Faculty of Veterinary Medicine, Utrecht University, 3584CS Utrecht, the Netherlands
| | - Julia Bodaneze
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Marit Biesheuvel
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - David F Kelton
- Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Tamaki Uyama
- Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Simon Dufour
- Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC, Canada J2S 2M2
| | - Javier Sanchez
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada C1A 4P3
| | - Daniella Rizzo
- Public Health Agency of Canada, Centre for Foodborne, Environmental and Zoonotic Infectious Diseases, Guelph, ON, Canada N1H 8J1
| | - David Léger
- Public Health Agency of Canada, Centre for Foodborne, Environmental and Zoonotic Infectious Diseases, Guelph, ON, Canada N1H 8J1
| | - Herman W Barkema
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1; One Health at UCalgary, University of Calgary, Calgary, AB, Canada T2N 4N1
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de Jong E, McCubbin KD, Speksnijder D, Dufour S, Middleton JR, Ruegg PL, Lam TJGM, Kelton DF, McDougall S, Godden SM, Lago A, Rajala-Schultz PJ, Orsel K, De Vliegher S, Krömker V, Nobrega DB, Kastelic JP, Barkema HW. Invited review: Selective treatment of clinical mastitis in dairy cattle. J Dairy Sci 2023; 106:3761-3778. [PMID: 37080782 DOI: 10.3168/jds.2022-22826] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 01/01/2023] [Indexed: 04/22/2023]
Abstract
Treatment of clinical mastitis (CM) and use of antimicrobials for dry cow therapy are responsible for the majority of animal-defined daily doses of antimicrobial use (AMU) on dairy farms. However, advancements made in the last decade have enabled excluding nonsevere CM cases from antimicrobial treatment that have a high probability of cure without antimicrobials (no bacterial causes or gram-negative, excluding Klebsiella spp.) and cases with a low bacteriological cure rate (chronic cases). These advancements include availability of rapid diagnostic tests and improved udder health management practices, which reduced the incidence and infection pressure of contagious CM pathogens. This review informed an evidence-based protocol for selective CM treatment decisions based on a combination of rapid diagnostic test results, review of somatic cell count and CM records, and elucidated consequences in terms of udder health, AMU, and farm economics. Relatively fast identification of the causative agent is the most important factor in selective CM treatment protocols. Many reported studies did not indicate detrimental udder health consequences (e.g., reduced clinical or bacteriological cures, increased somatic cell count, increased culling rate, or increased recurrence of CM later in lactation) after initiating selective CM treatment protocols using on-farm testing. The magnitude of AMU reduction following a selective CM treatment protocol implementation depended on the causal pathogen distribution and protocol characteristics. Uptake of selective treatment of nonsevere CM cases differs across regions and is dependent on management systems and adoption of udder health programs. No economic losses or animal welfare issues are expected when adopting a selective versus blanket CM treatment protocol. Therefore, selective CM treatment of nonsevere cases can be a practical tool to aid AMU reduction on dairy farms.
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Affiliation(s)
- Ellen de Jong
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1; One Health at UCalgary, University of Calgary, AB, Canada T2N 4N1; Mastitis Network, Saint-Hyacinthe, QC, Canada J25 2M2
| | - Kayley D McCubbin
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1; One Health at UCalgary, University of Calgary, AB, Canada T2N 4N1; Mastitis Network, Saint-Hyacinthe, QC, Canada J25 2M2
| | - David Speksnijder
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, the Netherlands; University Animal Health Clinic ULP, 3481 LZ Harmelen, the Netherlands
| | - Simon Dufour
- Mastitis Network, Saint-Hyacinthe, QC, Canada J25 2M2; Department of Pathology and Microbiology, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada J2S 2M2
| | - John R Middleton
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia 65211
| | - Pamela L Ruegg
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing 48824
| | - Theo J G M Lam
- Department Population Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, the Netherlands; GD Animal Health, 7400 AA Deventer, the Netherlands
| | - David F Kelton
- Mastitis Network, Saint-Hyacinthe, QC, Canada J25 2M2; Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Scott McDougall
- Cognosco, Anexa, Morrinsville 3340, New Zealand; School of Veterinary Science, Massey University, Palmerston North 4442, New Zealand
| | - Sandra M Godden
- Department of Veterinary Population Medicine, University of Minnesota, St. Paul 55108
| | | | - Päivi J Rajala-Schultz
- Department of Production Animal Medicine, Faculty of Veterinary Medicine, 00014 University of Helsinki, Finland
| | - Karin Orsel
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Sarne De Vliegher
- M-team and Mastitis and Milk Quality Research Unit, Department of Internal Medicine, Reproduction and Population Health, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium
| | - Volker Krömker
- Section for Animal Production, Nutrition and Health, Department of Veterinary and Animal Sciences, University of Copenhagen, 1870 Frederiksberg, Denmark
| | - Diego B Nobrega
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1; One Health at UCalgary, University of Calgary, AB, Canada T2N 4N1
| | - John P Kastelic
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Herman W Barkema
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1; One Health at UCalgary, University of Calgary, AB, Canada T2N 4N1; Mastitis Network, Saint-Hyacinthe, QC, Canada J25 2M2.
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6
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Martínez EP, Golding SE, van Rosmalen J, Vinueza-Burgos C, Verbon A, van Schaik G. Antibiotic prescription patterns and non-clinical factors influencing antibiotic use by Ecuadorian veterinarians working on cattle and poultry farms: A cross-sectional study. Prev Vet Med 2023; 213:105858. [PMID: 36724619 DOI: 10.1016/j.prevetmed.2023.105858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 12/10/2022] [Accepted: 01/22/2023] [Indexed: 01/24/2023]
Abstract
Understanding antibiotic prescription patterns and non-clinical factors influencing antibiotic use is essential for implementing strategies to promote appropriate antibiotic use. There is, however, limited research exploring these issues with Ecuadorian veterinarians. Therefore, a questionnaire was developed and applied cross-sectionally to veterinarians (n = 173) from two professional organizations to explore the antibiotic prescription patterns and non-clinical factors (e.g., attitudes and perceptions) influencing antibiotic use, and to identify strategies to reduce antibiotic use. The response rate was 78.4%. Responses were compared between veterinarians working mainly on cattle and poultry farms using Mann-Whitney U tests. The most important attitudes, beliefs and perceptions towards antimicrobial resistance (AMR) and antibiotic use were identified with the Relative Importance Index (RII). Veterinarians showed high awareness of AMR and its implications for public health, as well as the necessity of reducing antibiotic use. However, some veterinarians appear to underestimate the potential contribution of veterinary antibiotic use on AMR in humans. Veterinarians self-reported high prescription (> 20%) of antibiotics for cattle and poultry that are critically important for human medicine, such as 3rd and 4th generation cephalosporins, polymyxins and quinolones. Further, antibiotic therapy was not tailored to disease type. Cattle and poultry veterinarians perceived similar barriers to increasing antibiotic stewardship including: poor biosecurity measures, animal confinement, low feed quality, farmers' behaviors (such as stopping antibiotic treatment, storing antibiotics on farms, buying antibiotics in veterinary supply stores), and sales agents' roles as non-professional prescribers of antibiotics. Overall, veterinarians were broadly supportive (>90%) of most strategies to promote appropriate antibiotic use. They saw more merit in improving biosecurity of farms and implementing educational programs for farmers and veterinarians. This study provides insight into the complexity of antibiotic use on Ecuadorian farms and the need for holistic strategies in a One Health context, to achieve antibiotic stewardship.
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Affiliation(s)
- Evelyn Pamela Martínez
- Facultad de Medicina Veterinaria y Zootecnia, Universidad Central del Ecuador, Quito 170103, Ecuador; Department of Microbiology and Infectious Diseases, Erasmus MC, University Medical Centre, PO Box 2040, 3000 CA Rotterdam, the Netherlands.
| | - Sarah E Golding
- School of Psychology, Faculty of Health and Medical Sciences, Stag Hill Campus, University of Surrey, GU2 7XH Guildford, United Kingdom.
| | - Joost van Rosmalen
- Department of Biostatistics, Erasmus MC, University Medical Centre, PO Box 2040, 3000 CA Rotterdam, the Netherlands; Department of Epidemiology, Erasmus MC, University Medical Centre, PO Box 2040, 3000 CA Rotterdam, the Netherlands
| | - Christian Vinueza-Burgos
- Unidad de Investigación de Enfermedades Transmitidas por Alimentos y Resistencia a los Antimicrobianos (UNIETAR), Facultad de Medicina Veterinaria y Zootecnia, Universidad Central del Ecuador, Quito 170103, Ecuador.
| | - Annelies Verbon
- Department of Microbiology and Infectious Diseases, Erasmus MC, University Medical Centre, PO Box 2040, 3000 CA Rotterdam, the Netherlands.
| | - Gerdien van Schaik
- Department of Population Health Sciences, Unit Farm Animal Health, Utrecht University, Yalelaan 7, 3584 CL Utrecht, the Netherlands; Royal GD, Deventer, the Netherlands.
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7
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Rowe S, Kabera F, Dufour S, Godden S, Roy JP, Nydam D. Selective dry-cow therapy can be implemented successfully in cows of all milk production levels. J Dairy Sci 2023; 106:1953-1967. [PMID: 36653288 DOI: 10.3168/jds.2022-22547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 09/23/2022] [Indexed: 01/18/2023]
Abstract
Antibiotic stewardship on dairy farms can be heightened through the implementation of selective dry-cow therapy (SDCT). However, some producers are concerned that this practice may be related to poor udder health outcomes in cows with high milk production at the time of dry-off. The objective of this study was to evaluate if the effect of culture-guided SDCT (Cult-SDCT) and algorithm-guided SDCT (Alg-SDCT) on dry-period intramammary infection (IMI) dynamics and postcalving udder health and performance [when compared with blanket dry-cow therapy (BDCT)] varied according to milk production level before dry-off. Data were compiled from clinical trials conducted in the United States and Canada that compared Cult-SDCT and Alg-SDCT to a positive control, i.e., BDCT. In those trials, cows were enrolled 1-2 d before dry-off, randomized to their dry-cow therapy strategy and followed until 120 d in milk of the subsequent lactation. The number of cows and quarters in the final data set were 1,485 and 5,097, respectively. Measured outcomes included quarter-level antibiotic use at dry-off, quarter-level IMI prevalence after calving, quarter-level dry-period IMI cure risk, quarter-level dry-period new IMI risk, cow-level clinical mastitis and removal from the herd during 1-120 d in milk, and somatic cell count and milk yield during 1-120 DIM. The primary objective of analysis was to investigate if the effect of Cult-SDCT and Alg-SDCT on these outcomes, when compared with BDCT, varied according to milk production level before dry-off. To do this, each cow was classified as having low, mid or high production, based on her milk yield tertile group at the most recent herd test before enrollment (low: <23.7 kg/d, mid: 23.7 to 30.4 kg/d, and high >30.4 kg/d). Multivariable generalized estimating equations were used to estimate risk differences and differences in means, and Cox regression was used to estimate hazard ratios. For Cult-SDCT, the proportion of quarters treated with dry-cow antibiotics within each milk production level were 40.7% (low), 41.7% (mid) and 47.2% (high). For Alg-SDCT, the proportions were 60.6% (low), 38.7% (mid), and 35.1% (high). Measures of udder health were not markedly different when comparing Cult-SDCT to BDCT and Alg-SDCT to BDCT. This was consistently observed in low, mid and high producing cows. In conclusion, the findings from this study indicate that Cult-SDCT and Alg-SDCT can be successfully implemented in cows of all milk production levels.
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Affiliation(s)
- Sam Rowe
- Sydney School of Veterinary Science, The University of Sydney, Camden, New South Wales 2570, Australia; Department of Veterinary Population Medicine, University of Minnesota, St. Paul 55108.
| | - Fidele Kabera
- Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada J2S 2M2; Mastitis Network, Saint-Hyacinthe, Quebec, Canada J2S 2M2
| | - Simon Dufour
- Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada J2S 2M2; Mastitis Network, Saint-Hyacinthe, Quebec, Canada J2S 2M2
| | - Sandra Godden
- Department of Veterinary Population Medicine, University of Minnesota, St. Paul 55108
| | - Jean-Philippe Roy
- Mastitis Network, Saint-Hyacinthe, Quebec, Canada J2S 2M2; Département de sciences cliniques, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada J2S 2M2
| | - Daryl Nydam
- Department of Public and Ecosystem Health, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853
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8
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McCubbin KD, de Jong E, Lam TJGM, Kelton DF, Middleton JR, McDougall S, De Vliegher S, Godden S, Rajala-Schultz PJ, Rowe S, Speksnijder DC, Kastelic JP, Barkema HW. Invited review: Selective use of antimicrobials in dairy cattle at drying-off. J Dairy Sci 2022; 105:7161-7189. [PMID: 35931474 DOI: 10.3168/jds.2021-21455] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 04/27/2022] [Indexed: 11/19/2022]
Abstract
Administering intramammary antimicrobials to all mammary quarters of dairy cows at drying-off [i.e., blanket dry cow therapy (BDCT)] has been a mainstay of mastitis prevention and control. However, as udder health has considerably improved over recent decades with reductions in intramammary infection prevalence at drying-off and the introduction of teat sealants, BDCT may no longer be necessary on all dairy farms, thereby supporting antimicrobial stewardship efforts. This narrative review summarizes available literature regarding current dry cow therapy practices and associated impacts of selective dry cow therapy (SDCT) on udder health, milk production, economics, antimicrobial use, and antimicrobial resistance. Various methods to identify infections at drying-off that could benefit from antimicrobial treatment are described for selecting cows or mammary quarters for treatment, including utilizing somatic cell count thresholds, pathogen identification, previous clinical mastitis history, or a combination of criteria. Selection methods may be enacted at the herd, cow, or quarter levels. Producers' and veterinarians' motivations for antimicrobial use are discussed. Based on review findings, SDCT can be adopted without negative consequences for udder health and milk production, and concurrent teat sealant use is recommended, especially in udder quarters receiving no intramammary antimicrobials. Furthermore, herd selection should be considered for SDCT implementation in addition to cow or quarter selection, as BDCT may still be temporarily necessary in some herds for optimal mastitis control. Costs and benefits of SDCT vary among herds, whereas impacts on antimicrobial resistance remain unclear. In summary, SDCT is a viable management option for maintaining udder health and milk production while improving antimicrobial stewardship in the dairy industry.
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Affiliation(s)
- Kayley D McCubbin
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1; One Health at UCalgary, University of Calgary, AB, Canada T2N 4N1
| | - Ellen de Jong
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1; One Health at UCalgary, University of Calgary, AB, Canada T2N 4N1
| | - Theo J G M Lam
- Department Population Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584CS Utrecht, the Netherlands
| | - David F Kelton
- Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - John R Middleton
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia 65211
| | - Scott McDougall
- Cognosco, Anexa FVC Morrinsville, PO Box 21, Morrinsville 3340, New Zealand; School of Veterinary Science, Massey University, Palmerston North 4474, New Zealand
| | - Sarne De Vliegher
- M-team and Mastitis and Milk Quality Research Unit, Department of Reproduction, Obstetrics, and Herd Health, Faculty of Veterinary Medicine, Ghent University, 9820, Merelbeke, Belgium
| | - Sandra Godden
- College of Veterinary Medicine, University of Minnesota, St. Paul 55108
| | - Päivi J Rajala-Schultz
- Department of Production Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, 04920 Saarentaus, Finland
| | - Sam Rowe
- Faculty of Science, Sydney School of Veterinary Science, The University of Sydney, Camden, New South Wales 2570, Australia
| | - David C Speksnijder
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584CS Utrecht, the Netherlands; University Farm Animal Clinic ULP, 3481LZ Harmelen, the Netherlands
| | - John P Kastelic
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Herman W Barkema
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1; One Health at UCalgary, University of Calgary, AB, Canada T2N 4N1.
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Tijs SHW, Holstege MMC, Scherpenzeel CGM, Santman-Berends IMGA, Velthuis AGJ, Lam TJGM. Effect of selective dry cow treatment on udder health and antimicrobial usage on Dutch dairy farms. J Dairy Sci 2022; 105:5381-5392. [PMID: 35379456 DOI: 10.3168/jds.2021-21026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 02/14/2022] [Indexed: 11/19/2022]
Abstract
Since 2013, selective dry cow treatment (SDCT) has been the standard approach in the Netherlands where farmers select cows for the use of antimicrobials at drying-off. Shortly after its introduction, antimicrobial usage decreased significantly, and no significant association was found between the level of SDCT and clinical mastitis (CM). Obviously, at that time long-term associations could not be evaluated. This study aimed to provide insight into the methods and level of implementation of SDCT on Dutch dairy farms with a conventional milking system (CMS) or an automatic milking system (AMS) in 2016 and 2017, several years after the implementation of SDCT. Udder health and antimicrobial use were also assessed. For this study, 262 farmers recorded dry cow treatments as well as all CM cases in the period from May 1, 2016, until April 30, 2017. Additionally, somatic cell count (SCC) data on cow and herd level, treatment data on herd level and questionnaire results on udder health management were collected. Data were analyzed using descriptive statistics with differences between milking systems being evaluated using nonparametric univariable statistics. In the study period, SDCT was applied on almost all (98.8%) of the participating dairy farms. The main reason for applying antimicrobials at drying-off was either the SCC history during the complete previous lactation or the SCC at the last milk recording before drying-off. The median percentage of cows treated with antimicrobials was 48.5%. The average incidence rate of CM was 27.3 cases per 100 cows per year. From all CM cases that were registered per herd, on average 32.8% were scored as mild, 42.2% as moderate, and 25.0% as severe CM. The mean bulk tank SCC of the herds was 168,989 cells/mL. A cow was considered to have subclinical mastitis (SCM) if individual SCC was ≥150,000 cells/mL for primiparous and ≥250,000 cells/mL for multiparous cows. Passing these threshold values after 2 earlier low SCC values was considered a new case of SCM. The mean incidence rate of SCM in these herds was 62.5 cases per 100 cows per year. Bulk tank SCC and the incidence rate of SCM on farms with a CMS were statistically lower than on farms with an AMS, whereas the incidence rate of CM did not significantly differ between both groups of farms. The AMS farms had more cows per herd treated with antimicrobials at drying-off and a larger proportion of severe CM cases than did CMS farms. It is unknown whether the differences are due to the milking system or to other differences between both types of farms. This study showed the level of adoption of SDCT, udder health, and antimicrobial usage parameters several years after the ban on the preventive use of antimicrobials in animal husbandry. It found that udder health parameters did not differ from those found in Dutch studies before and around the time of implementing SDCT, whereas SDCT was widely applied on Dutch dairy farms during the study period. Therefore, it was concluded that Dutch dairy farmers were able to handle the changed policy of antimicrobial use at drying-off while maintaining indicators of a good udder health.
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Affiliation(s)
- S H W Tijs
- Royal GD, PO Box 9, 7400 AA Deventer, the Netherlands.
| | | | | | | | - A G J Velthuis
- Royal GD, PO Box 9, 7400 AA Deventer, the Netherlands; Aeres University of Applied Animal Science Dronten, De Drieslag 4, 8251 JZ Dronten, the Netherlands
| | - T J G M Lam
- Royal GD, PO Box 9, 7400 AA Deventer, the Netherlands; Department Population Health Sciences, Faculty of Veterinary Medicine, Utrecht University, PO Box 80151, 3508 TD Utrecht, the Netherlands
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10
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Cattaneo L, Piccioli-Cappelli F, Lopreiato V, Lovotti G, Arrigoni N, Minuti A, Trevisi E. Drying-off cows with low somatic cell count with or without antibiotic therapy: A pilot study addressing the effects on immunometabolism and performance in the subsequent lactation. Livest Sci 2021. [DOI: 10.1016/j.livsci.2021.104740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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11
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Milk Somatic Cell Count and Polymorphonuclear Cells in Healthy Quarters of Cows That Underwent Blanket and Selective Dry Therapy: An Italian Case Study. Vet Sci 2021; 8:vetsci8120298. [PMID: 34941824 PMCID: PMC8705708 DOI: 10.3390/vetsci8120298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 11/15/2021] [Accepted: 11/26/2021] [Indexed: 11/17/2022] Open
Abstract
The incidence of mastitis increases with parity in dairy cattle and multiparous cows are often treated at drying off to limit the risk of udder health issues and support mammary gland tissues recovery. Milk somatic cells count (SCC, cells/mL) comprises different white blood cells fractions and is worldwide used to monitor and genetically improve udder health. Nevertheless, only certain SCC fractions increase when an udder inflammation occurs. Considering that antibiotic use for preventive purposes will be forbidden in 2022, we compared two different dry therapy protocols, blanket (BDCT) and selective (SDCT), on different SCC fractions in healthy quarters milk. Multiparous Holstein cows were enrolled in a randomized controlled trial and SCC, neutrophils, macrophages, lymphocytes, polymorphonuclear cells (PMN) and differential somatic cell count (DSCC) recorded after the experimental drying off were available. Significant differences were observed between the two protocols, with more favorable parameters in BDCT than SDCT cows. Results showed that moving from BDCT to SDCT is expected to significantly increase some SCC fractions, such as PMN, in healthy quarters. The baseline SCC level at the onset of lactation was greater in cows under SDCT than BDCT. Although not significant, clinical mastitis prevalence was numerically lower in BDCT (7.32%) than SDCT (8.62%). In this study we referred to a limited number of cows, but still findings will be useful to improve the knowledge on the impact of SDCT on milk SCC fractions in healthy quarters.
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12
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McCubbin KD, Anholt RM, de Jong E, Ida JA, Nóbrega DB, Kastelic JP, Conly JM, Götte M, McAllister TA, Orsel K, Lewis I, Jackson L, Plastow G, Wieden HJ, McCoy K, Leslie M, Robinson JL, Hardcastle L, Hollis A, Ashbolt NJ, Checkley S, Tyrrell GJ, Buret AG, Rennert-May E, Goddard E, Otto SJG, Barkema HW. Knowledge Gaps in the Understanding of Antimicrobial Resistance in Canada. Front Public Health 2021; 9:726484. [PMID: 34778169 PMCID: PMC8582488 DOI: 10.3389/fpubh.2021.726484] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 09/16/2021] [Indexed: 01/21/2023] Open
Abstract
Current limitations in the understanding and control of antimicrobial resistance (AMR) in Canada are described through a comprehensive review focusing on: (1) treatment optimization; (2) surveillance of antimicrobial use and AMR; and (3) prevention of transmission of AMR. Without addressing gaps in identified areas, sustained progress in AMR mitigation is unlikely. Expert opinions and perspectives contributed to prioritizing identified gaps. Using Canada as an example, this review emphasizes the importance and necessity of a One Health approach for understanding and mitigating AMR. Specifically, antimicrobial use in human, animal, crop, and environmental sectors cannot be regarded as independent; therefore, a One Health approach is needed in AMR research and understanding, current surveillance efforts, and policy. Discussions regarding addressing described knowledge gaps are separated into four categories: (1) further research; (2) increased capacity/resources; (3) increased prescriber/end-user knowledge; and (4) policy development/enforcement. This review highlights the research and increased capacity and resources to generate new knowledge and implement recommendations needed to address all identified gaps, including economic, social, and environmental considerations. More prescriber/end-user knowledge and policy development/enforcement are needed, but must be informed by realistic recommendations, with input from all relevant stakeholders. For most knowledge gaps, important next steps are uncertain. In conclusion, identified knowledge gaps underlined the need for AMR policy decisions to be considered in a One Health framework, while highlighting critical needs to achieve realistic and meaningful progress.
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Affiliation(s)
- Kayley D. McCubbin
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
- One Health at UCalgary, University of Calgary, Calgary, AB, Canada
| | | | - Ellen de Jong
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
- One Health at UCalgary, University of Calgary, Calgary, AB, Canada
| | - Jennifer A. Ida
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Diego B. Nóbrega
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - John P. Kastelic
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - John M. Conly
- One Health at UCalgary, University of Calgary, Calgary, AB, Canada
- O'Brien Institute of Public Health, University of Calgary, Calgary, AB, Canada
- Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Department of Pathology and Laboratory Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Alberta Health Services, Calgary, AB, Canada
| | - Matthias Götte
- Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Tim A. McAllister
- Agriculture and Agri-Food Canada, Lethbridge Research Centre, Lethbridge, AB, Canada
| | - Karin Orsel
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
- One Health at UCalgary, University of Calgary, Calgary, AB, Canada
| | - Ian Lewis
- One Health at UCalgary, University of Calgary, Calgary, AB, Canada
- Department of Biological Sciences, Faculty of Science, University of Calgary, Calgary, AB, Canada
| | - Leland Jackson
- One Health at UCalgary, University of Calgary, Calgary, AB, Canada
- Department of Biological Sciences, Faculty of Science, University of Calgary, Calgary, AB, Canada
| | - Graham Plastow
- Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life and Environmental Sciences, University of Alberta, Edmonton, AB, Canada
| | - Hans-Joachim Wieden
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB, Canada
| | - Kathy McCoy
- One Health at UCalgary, University of Calgary, Calgary, AB, Canada
- Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Myles Leslie
- One Health at UCalgary, University of Calgary, Calgary, AB, Canada
- O'Brien Institute of Public Health, University of Calgary, Calgary, AB, Canada
- Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- School of Public Policy, University of Calgary, Calgary, AB, Canada
| | - Joan L. Robinson
- Department of Pediatrics, Faculty of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Lorian Hardcastle
- One Health at UCalgary, University of Calgary, Calgary, AB, Canada
- O'Brien Institute of Public Health, University of Calgary, Calgary, AB, Canada
- Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Faculty of Law, University of Calgary, Calgary, AB, Canada
| | - Aidan Hollis
- One Health at UCalgary, University of Calgary, Calgary, AB, Canada
- O'Brien Institute of Public Health, University of Calgary, Calgary, AB, Canada
- Department of Economics, Faculty of Arts, University of Calgary, Calgary, AB, Canada
| | - Nicholas J. Ashbolt
- Faculty of Science and Engineering, Southern Cross University, Lismore, NSW, Australia
| | - Sylvia Checkley
- One Health at UCalgary, University of Calgary, Calgary, AB, Canada
- O'Brien Institute of Public Health, University of Calgary, Calgary, AB, Canada
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Gregory J. Tyrrell
- Alberta Precision Laboratories, Alberta Health Services, Calgary, AB, Canada
- Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry, University of Alberta, Calgary, AB, Canada
| | - André G. Buret
- One Health at UCalgary, University of Calgary, Calgary, AB, Canada
- Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
- Department of Biological Sciences, Faculty of Science, University of Calgary, Calgary, AB, Canada
| | - Elissa Rennert-May
- One Health at UCalgary, University of Calgary, Calgary, AB, Canada
- O'Brien Institute of Public Health, University of Calgary, Calgary, AB, Canada
- Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
- Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Alberta Health Services, Calgary, AB, Canada
- Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Ellen Goddard
- Department of Resource Economics and Environmental Sociology, Faculty of Agriculture, Life and Environmental Science, University of Alberta, Edmonton, AB, Canada
| | - Simon J. G. Otto
- HEAT-AMR Research Group, School of Public Health, University of Alberta, Edmonton, AB, Canada
- Thematic Area Lead, Healthy Environments, Centre for Healthy Communities, School of Public Health, University of Alberta, Edmonton, AB, Canada
| | - Herman W. Barkema
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
- One Health at UCalgary, University of Calgary, Calgary, AB, Canada
- O'Brien Institute of Public Health, University of Calgary, Calgary, AB, Canada
- Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
- Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
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13
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Rowe SM, Vasquez AK, Godden SM, Nydam DV, Royster E, Timmerman J, Boyle M. Evaluation of 4 predictive algorithms for intramammary infection status in late-lactation cows. J Dairy Sci 2021; 104:11035-11046. [PMID: 34253362 DOI: 10.3168/jds.2021-20504] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 05/28/2021] [Indexed: 11/19/2022]
Abstract
The objective of this observational study was to compare 4 cow-level algorithms to predict cow-level intramammary infection (IMI) status (culture and MALDI-TOF) in late-lactation US dairy cows using standard measures of test performance. Secondary objectives were to estimate the likely effect of each algorithm, if used to guide selective dry cow therapy (SDCT), on dry cow antibiotic use in US dairy herds, and to investigate the importance of including clinical mastitis criteria in algorithm-guided SDCT. Cows (n = 1,594) from 56 US dairy herds were recruited as part of a previously published cross-sectional study of bedding management and IMI in late-lactation cows. Each herd was visited twice for sampling. At each farm visit, aseptic quarter-milk samples were collected from 20 cows approaching dry-off (>180 d pregnant), which were cultured using standard bacteriological methods and MALDI-TOF for identification of isolates. Quarter-level culture results were used to establish cow-level IMI status, which was considered the reference test in this study. Clinical mastitis records and Dairy Herd Improvement Association test-day somatic cell count data were extracted from herd records and used to perform cow-level risk assessments (low vs. high risk) using 4 algorithms that have been proposed for SDCT in New Zealand, the Netherlands, United Kingdom, and the United States. Agreement between aerobic culture (reference test; IMI vs. no-IMI) and algorithm status (high vs. low risk) was described using Cohen's kappa, test sensitivity, specificity, negative predictive value, and positive predictive value. The proportion of cows classified as high risk among the 4 algorithms ranged from 0.31 to 0.63, indicating that these approaches to SDCT could reduce antibiotic use at dry-off by 37 to 69% in the average US herd. All algorithms had poor agreement with IMI status, with kappa values ranging from 0.05 to 0.13. Sensitivity varied by pathogen, with higher values observed when detecting IMI caused by Streptococcus uberis, Streptococcus dysgalactiae, Staphylococcus aureus, and Lactococcus lactis. Negative predictive values were high for major pathogens among all algorithms (≥0.87), which may explain why algorithm-guided SDCT programs have been successfully implemented in field trials, despite poor agreement with overall IMI status. Removal of clinical mastitis criteria for each algorithm had little effect on the algorithm classification of cows, indicating that algorithms based on SCC alone may have similar performance to those based on SCC and clinical mastitis criteria. We recommend that producers implementing algorithm-guided SDCT use algorithm criteria that matches their relative aspirations for reducing antibiotic use (high specificity, positive predictive value) or minimizing untreated IMI at dry-off (high sensitivity, negative predictive value).
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Affiliation(s)
- S M Rowe
- Sydney School of Veterinary Science, The University of Sydney, Camden, New South Wales 2570, Australia; Department of Veterinary Population Medicine, University of Minnesota, St. Paul 55108.
| | | | - S M Godden
- Department of Veterinary Population Medicine, University of Minnesota, St. Paul 55108
| | - D V Nydam
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853
| | - E Royster
- Department of Veterinary Population Medicine, University of Minnesota, St. Paul 55108
| | - J Timmerman
- Department of Veterinary Population Medicine, University of Minnesota, St. Paul 55108
| | - M Boyle
- Zoetis, Hager City, WI 54014
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