title: Association of cow and quarter-level factors at drying-off with new intramammary infections during the dry period.
abstract: Our objective was to describe cow and quarter-level factors associated with drying-off, and to evaluate their impacts on new intramammary infections (IMI) during the dry period. Data from 300 cows in five research herds were collected starting 2 weeks prior to scheduled drying-off. Variables of interest included daily milk production, teat-end integrity, formation of the teat-canal keratin plug, and quarter-milk bacteriological culture results. Overall, 11% of quarters developed new IMI in the dry period; this varied by herd, parity and time of the study. Most new IMI were caused by environmental streptococci and coliform organisms (34 and 30%, respectively). Quarters that had a cracked teat-end had higher odds of developing new infections than those without cracks (15 and 10%, respectively). Quarters that formed a keratin plug early in the dry period had a lower odds than those that did not close (10 and 14%, respectively). After 6 dry weeks, 23% of quarters were still open. The hazard of quarters closing if milk production on the day prior to drying-off was >21 kg 1.8-times less.
authors.affiliation: University of Guelph, Guelph, Ont., Canada N1G 2W1. rdingwell@upei.ca
authors.forename: R T
authors.initials: RT
authors.lastname: Dingwell
authors.forename: K E
authors.initials: KE
authors.lastname: Leslie
authors.forename: Y H
authors.initials: YH
authors.lastname: Schukken
authors.forename: J M
authors.initials: JM
authors.lastname: Sargeant
authors.forename: L L
authors.initials: LL
authors.lastname: Timms
authors.forename: T F
authors.initials: TF
authors.lastname: Duffield
authors.forename: G P
authors.initials: GP
authors.lastname: Keefe
authors.forename: D F
authors.initials: DF
authors.lastname: Kelton
authors.forename: K D
authors.initials: KD
authors.lastname: Lissemore
authors.forename: J
authors.initials: J
authors.lastname: Conklin
mesh_terms: D000818:Animals; D002170:Canada / Q000453:epidemiology; D002417:Cattle; D003612:Dairying / Q000379:methods; D005260:Female; D007774:Lactation; D016015:Logistic Models; D008321:Mammary Glands, Animal / Q000382:microbiology* / Q000473:pathology; D008414:Mastitis, Bovine / Q000453:epidemiology / Q000209:etiology*; D008892:Milk / Q000378:metabolism / Q000382:microbiology*; D015995:Prevalence; D016016:Proportional Hazards Models; D012307:Risk Factors; D014481:United States / Q000453:epidemiology