Metataxonomic and immunological analysis of milk from ewes with or without a history of mastitis

摘要

Mastitis is a highly prevalent condition that has agreat impact on milk production and animal welfare,and often requires substantial management efforts.For this reason, it is generally considered an importantthreat to the dairy industry. Many microbial,host, and environmental factors can protect against,predispose to, or influence the development of mastitis.The objective of this work was to characterize the milkmicrobiota of Manchega ewes, and to compare samplesfrom animals with and without a history of mastitis.We analyzed milk samples from 36 ewes belonging to 2different farms (18 ewes from each farm) using culturedependentand culture-independent techniques. Wealso analyzed several immune compounds to investigateassociations of mastitis with 3 main variables: farm;history of mastitis or no mastitis; and parity number.Both culture-dependent and culture-independent techniquesshowed that ewe milk harbored a site-specificcomplex microbiota and microbiome. Staphylococcusepidermidis was the main species driving the differencebetween farm A (where it was the dominant species)and B (where it was not). In contrast, samples fromfarm B were characterized by the presence of a widespectrum of other coagulase-negative staphylococci.Some of these species have already been associatedwith subclinical intramammary infections in ruminants.Of the 10 immune compounds assayed in this study, 3were related to a history of mastitis [IL-8, IFN-γ, andIFN-gamma-induced protein 10 (IP-10)]. Increases inIL-8 concentrations in milk seemed to be a feature ofsubclinical mastitis in sheep, and in this study, thisimmune factor was detected only in samples from eweswith some episodes of mastitis and from the group withthe highest somatic cell count. We also observed a positivecorrelation between the samples with the highestsomatic cell count and IFN-γ and IP-10 levels. Our resultssuggest that these 3 compounds could be used asbiomarkers for the negative selection of mastitis-proneanimals, particularly when somatic cell count is veryhigh.