title: Staphylococcus aureus intramammary infection affects milk yield and SCC of dairy cows.
abstract: Staphylococcus aureus (S. aureus) is the most prevalent infectious microorganism affecting dairy cattle worldwide, and its pathogenic characteristics facilitate its spread in dairy herds. S. aureus intramammary infections (IMI) are mainly subclinical, and associated losses can exceed average herd losses where the pathogen is not isolated. However, the extent it affects milk composition at udder and quarter levels is still unknown, and cow composite milk losses may be underestimated due to the dilution effect. The aim of this study was to investigate the effects of S. aureus subclinical mastitis on mammary quarter milk yield and composition. In order to determine the effects of the pathogen on milk yield and composition at quarter level, a pairwise comparison of infected and non-infected mammary quarters (n = 28) from two dairy herds was carried out. Quarters were individually milked, and milk production and composition were assessed. S. aureus has increased somatic cell counts at quarter level; however, no effect of S. aureus IMI on milk lactose, fat, and protein contents was observed. Fat yield from infected quarters decreased, but losses due to the infection caused by S. aureus were not associated with quarter positioning in cows.
authors.affiliation: Department of Preventive Veterinary Medicine and Animal Health, School of Veterinary Medicine and Animal Sciences, University of São Paulo, 87 - Cidade Universitária, São Paulo, 05508-270, Brazil.
authors.forename: Bruno Garcia
authors.initials: BG
authors.lastname: Botaro
authors.forename: Cristina Simões
authors.initials: CS
authors.lastname: Cortinhas
authors.forename: Aline Gerato
authors.initials: AG
authors.lastname: Dibbern
authors.forename: Luis Felipe Prada
authors.initials: LF
authors.lastname: e Silva
authors.forename: Nilson Roberti
authors.initials: NR
authors.lastname: Benites
authors.forename: Marcos Veiga
authors.initials: MV
authors.lastname: dos Santos
mesh_terms: D000818:Animals; D002417:Cattle; D002452:Cell Count / Q000662:veterinary; D003612:Dairying; D004041:Dietary Fats / Q000032:analysis; D004044:Dietary Proteins / Q000032:analysis; D005260:Female; D005516:Food Microbiology; D007785:Lactose / Q000032:analysis; D008321:Mammary Glands, Animal / Q000382:microbiology*; D008414:Mastitis, Bovine / Q000382:microbiology*; D008892:Milk / Q000737:chemistry* / Q000382:microbiology; D015995:Prevalence; D013203:Staphylococcal Infections / Q000662:veterinary*; D013211:Staphylococcus aureus / Q000302:isolation & purification*
chemical_list: D004041:Dietary Fats; D004044:Dietary Proteins; D007785:Lactose