Bacteriological outcomes following random allocation to quarter-level selection based on California Mastitis Test score or cow-level allocation based on somatic cell count for dry cow therapy

Simple item page
dc.citation.issue3
dc.citation.volume105
dc.contributor.authorMcDougall S
dc.contributor.authorWilliamson J
dc.contributor.authorLacy-Hulbert J
dc.coverage.spatialUnited States
dc.date.accessioned2024-02-02T02:23:18Z
dc.date.accessioned2024-07-25T06:45:45Z
dc.date.available2022-01-25
dc.date.available2024-02-02T02:23:18Z
dc.date.available2024-07-25T06:45:45Z
dc.date.issued2022-03
dc.description.abstractIntramammary infusion of antimicrobials at the end of lactation (dry cow therapy) has been a cornerstone of mastitis management for many years. However, as only a proportion of cows are infected at this time, treating only those cows likely to be infected is an important strategy to reduce antimicrobial usage and minimize risk of emergence of antimicrobial resistance. Such an approach requires the ability to discriminate between cows and quarters likely to be infected and uninfected. This study compared assignment of cows or quarters to antimicrobial treatment at the end of lactation based on cow composite somatic cell count (SCC; i.e., all quarters of cows with a maximum SCC across lactation >200,000 cells/mL received an antimicrobial; n = 891 cows, SCC-group) or assignment to quarter-level treatment based on a quarter level California Mastitis Test (CMT) score ≥ trace (n = 884 cows; CMT-group) performed immediately before drying off. All quarters of all cows also received an infusion of a bismuth-based internal teat sealant. Milk samples were collected for microbiology following the last milking, and again within 4 d of calving. Clinical mastitis records from dry off to 30 d into the subsequent lactation were collected. Multilevel, multivariable models were used to assess the effect of assignment to antimicrobial treatment. At drying off, a total of 575 (8.8%) and 147 (2.3%) of the 6,528 quarters had a minor, and a major intramammary infection (IMI), respectively. At drying off, 2089/3270 (63.9%) and 883/3311 (26.7%) of quarters were treated with dry cow therapy in the CMT and SCC-groups, respectively. Apparent bacteriological cure proportion for any IMI was higher in quarters assigned to the CMT than the SCC-group (349/368 (0.95, 95% CI 0.92-0.97) versus 313/346 (0.90, 95% CI 0.87-0.93)). New IMI proportion was lower among quarters assigned to the CMT than SCC-group [101/3,212 (0.032, 95% CI 0.025-0.038) versus 142/3,232 (0.044, 95% CI 0.036-0.051)]. The prevalence of any IMI postcalving was lower in quarters assigned to the CMT than SCC-group [119/3,243 (0.037, 95% CI: 0.030-0.044) versus 173/3,265 (0.054, 95% CI: 0.045-0.062)]. There was no difference in incidence of clinical mastitis between treatment groups. The total mass of antimicrobials used was 63% higher in the CMT-group than in the SCC-group (3.47 versus 2.12 mg/kg of liveweight). Selection of quarters for antimicrobial treatment at the end of lactation based on CMT resulted in greater proportion undergoing bacteriological cure, reduced risk of any new IMI and reduced post calving prevalence of any IMI compared with selection of cows based on SCC. However, CMT-based selection resulted in higher antimicrobial use compared with SCC-based selection, and further research is required to analyze the cost benefit and impact on risk of antimicrobial resistance of these 2 strategies.
dc.description.confidentialfalse
dc.edition.editionMarch 2022
dc.format.pagination2453-2472
dc.identifier.author-urlhttps://www.ncbi.nlm.nih.gov/pubmed/35086708
dc.identifier.citationMcDougall S, Williamson J, Lacy-Hulbert J. (2022). Bacteriological outcomes following random allocation to quarter-level selection based on California Mastitis Test score or cow-level allocation based on somatic cell count for dry cow therapy.. J Dairy Sci. 105. 3. (pp. 2453-2472).
dc.identifier.doi10.3168/jds.2021-21020
dc.identifier.eissn1525-3198
dc.identifier.elements-typejournal-article
dc.identifier.issn0022-0302
dc.identifier.piiS0022-0302(22)00023-6
dc.identifier.urihttps://mro.massey.ac.nz/handle/10179/70823
dc.languageeng
dc.publisherElsevier Inc and the Federation of Animal Science Societies (Fass) Inc on behalf of the American Dairy Science Association
dc.publisher.urihttps://www.journalofdairyscience.org/article/S0022-0302(22)00023-6/fulltext
dc.relation.isPartOfJ Dairy Sci
dc.rights(c) 2021 The Author/s
dc.rightsCC BY 4.0
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subjectCalifornia Mastitis Test
dc.subjectcow-selection
dc.subjectdry cow therapy
dc.subjectAnimals
dc.subjectAnti-Bacterial Agents
dc.subjectCattle
dc.subjectCattle Diseases
dc.subjectCell Count
dc.subjectFemale
dc.subjectLactation
dc.subjectMammary Glands, Animal
dc.subjectMastitis, Bovine
dc.subjectMilk
dc.titleBacteriological outcomes following random allocation to quarter-level selection based on California Mastitis Test score or cow-level allocation based on somatic cell count for dry cow therapy
dc.typeJournal article
pubs.elements-id450863
pubs.organisational-groupOther
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