title: Short communication: association between milk yield at dry-off and probability of intramammary infections at calving.
abstract: The association between milk yield at dry-off and intramammary infections at calving was evaluated from 116 lactations in one herd. Duplicate quarter samples were collected within 3 d after calving to estimate prevalence of intramammary infection at calving; information on cows' parity, daily milk yields, weekly somatic cell counts, and dry-off and calving dates were available for the data analyses. Generalized linear models with logit link were used to model the probability of a cow or a quarter being infected at calving, accounting for the clustered data. Increasing milk production at dry-off was a significant risk factor for both a cow and a quarter being infected with environmental pathogens at calving, but infections caused by coagulase-negative staphylococci at calving were not associated with milk yield at dry-off. For every 5-kg increase in milk yield at dry-off above 12.5 kg, the odds of a cow having an environmental intramammary infection at calving increased at least by 77%.
authors.affiliation: Department of Veterinary Preventive Medicine, The Ohio State University, Columbus 43210, USA. rajala-schultz.1@osu.edu
authors.forename: P J
authors.initials: PJ
authors.lastname: Rajala-Schultz
authors.forename: J S
authors.initials: JS
authors.lastname: Hogan
authors.forename: K L
authors.initials: KL
authors.lastname: Smith
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D005260:Female; D007774:Lactation / Q000502:physiology*; D008414:Mastitis, Bovine / Q000453:epidemiology*; D036801:Parturition; D011247:Pregnancy