title: Relationship of milk proteins in blood with somatic cell counts in milk of dairy cows.
abstract: Intramammary leucocytosis was induced by injection of Escherichia coli endotoxin via the teat canal in three lactating Holstein cows. Concentrations of alpha-lactalbumin and casein in blood serum were measured, and somatic cell concentration and yield and composition of milk were determined. Endotoxin injection elicited mean increases of 100-fold in somatic cell concentration and 50% in protein concentration, whereas milk yield declined 5-fold and lactose concentration was halved. Concentrations of alpha-lactalbumin and casein in blood rose from 80 to 1909 and 0 to 1231 ng/ml, respectively. By 96 h postinjection, all variables were approximately equal to those preinjection. In a second study, concentration of alpha-lactalbumin was determined in blood of lactating cows in two herds (n = 332) and related to milk somatic cell count. Concentrations of alpha-lactalbumin in blood were correlated with somatic cell counts (r = .60). Mean concentrations of alpha-lactalbumin increased with increasing cell count even at low somatic cell concentrations (25 to 250 X 10(3)). Concentrations of milk proteins in blood serum apparently reflect competency of the blood-milk barrier and may therefore yield an indirect measure of udder health.
authors.affiliation: Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061.
authors.forename: T B
authors.initials: TB
authors.lastname: McFadden
authors.forename: R M
authors.initials: RM
authors.lastname: Akers
authors.forename: A V
authors.initials: AV
authors.lastname: Capuco
mesh_terms: D000818:Animals; D002364:Caseins / Q000097:blood; D002417:Cattle / Q000097:blood / Q000502:physiology*; D004731:Endotoxins / Q000494:pharmacology*; D004926:Escherichia coli; D005260:Female; D007768:Lactalbumin / Q000097:blood; D007774:Lactation / Q000097:blood / Q000502:physiology*; D007962:Leukocytes / Q000276:immunology; D008321:Mammary Glands, Animal / Q000166:cytology / Q000187:drug effects; D008892:Milk / Q000166:cytology* / Q000187:drug effects; D008894:Milk Proteins / Q000097:blood*; D011247:Pregnancy; D011863:Radioimmunoassay
chemical_list: D002364:Caseins; D004731:Endotoxins; D008894:Milk Proteins; D007768:Lactalbumin