Factors associated with intramammary infection in dairy cows caused by coagulase-negative staphylococci, Staphylococcus aureus, Streptococcus uberis, Streptococcus dysgalactiae, Corynebacterium bovis, or Escherichia coli

Abstract

The aim of this study was to determine risk factors for bovine intramammary infection (IMI) associated with the most common bacterial species in Finland. Large databases of the Finnish milk-recording system and results of microbiological analyses of mastitic milk samples from Valio Ltd. (Helsinki, Finland) were analyzed. The study group comprised 29,969 cows with IMI from 4,173 dairy herds. A cow with a quarter milk sample in which DNA of target species was detected in the PathoProof Mastitis PCR Assay (Thermo Fisher Scientific, Waltham, MA) was determined to have IMI. Only cows with IMI caused by the 6 most common pathogens or groups of pathogens, coagulase-negative staphylococci (CNS), Staphylococcus aureus, Streptococcus uberis, Streptococcus dysgalactiae, Corynebacterium bovis, and Escherichia coli, were included. The control group comprised 160,176 IMI-free cows from the same herds as the study group. A multilevel logistic regression model was used to study herd-and cow-specific risk factors for incidence of IMI. Pathogen-specific results confirmed those of earlier studies, specifically that increasing parity increases prevalence of IMI regardless of causative pathogen. Holsteins were more susceptible to IMI than Nordic Reds except when the causative pathogen was CNS. Occurrence of IMI caused by C. bovis was not related to milk yield, in contrast to IMI caused by all other pathogens investigated. Organic milk production was associated with IMI only when the causative pathogen of IMI was Staph. aureus; Staph. aureus IMI was more likely to occur in conventional than in organic production. Cows in older freestall barns with parlor milking had an increased probability of contracting an IMI compared with cows in tiestall barns or in new freestall barns with automatic milking. This was the case for all IMI, except those caused by CNS, the prevalence of which was not associated with the milking system, and IMI caused by Staph. aureus, which was most common in cows housed in tiestall barns. A better breeding index for milk somatic cell count was associated with decreased occurrence of IMI, indicating that breeding for improved udder health has been successful in reducing the incidence of IMI caused by the most common pathogens in Finland. In the Finnish dairy sector, the importance of other measures to control IMI will increase as the Holstein breed progressively takes the place of the Nordic Red breed. Attention should be paid to hygiene and cleanliness, especially in old freestall barns. Based on our results, the increasing prevalence of automatic milking is not a reason for special concern.

Prevalence of subclinical mastitis in Finnish dairy cows: changes during recent decades and impact of cow and herd factors

“…High production herds with are usually managed expertly and breeding of the animals is systematic, which should improve udder health. In well-managed herds also treatment of mastitis is diagnosis-based and more efficient, which supports control of mastitis [33]. The dilution effect of the high milk yield on milk SCC may also play a role [31].…”

“…The design and functionality of free-stalls built after 2010, as well as their management, differ substantially from those in free-stalls built in 2001. In a recent study from Finland, AMS was not a significant risk factor for pathogen-specific intramammary infection [33]. …”

Knowledge gaps and research priorities inStaphylococcus aureusmastitis control

“…It is established that the severity of disease is determined by both the strain virulence and the host condition, but it is unknown to what extent manifestations (subclinical, mild, moderate, severe) and duration of infection are driven by host or pathogen (Fournier et al., ; Guinane et al., ; Haveri, Taponen, Vuopio‐Varkila, Salmenlinna, & Pyorala, ; Le Marechal et al., ; Plommet & Le Gall, ; Postle, Roguinsky, & Poutrel, ; Taponen, Liski, Heikkilä, & Pyörälä, ). The spread of infections within herds is also under the influence of strain contagiousness and hygiene practices as established by epidemiological studies.…”

“…As a consequence of its contagiousness and capacity to induce long‐lasting chronic infections, S. aureus is among the few major pathogens associated with endemic mastitis all over the world (Abera, Habte, Aragaw, Asmare, & Sheferaw, ; Acosta, da Silva, Medeiros, Pinheiro, & Mota, ; Levison et al., ; Petzer, Karzis, Watermeyer, van der Schans, & van Reenen, ; Piehler, Grimholt, Ovstebo, & Berg, ; Taponen et al., ; Wang et al., ). The prevalence of S. aureus mastitis has been reduced in countries or regions that implement the standard mastitis prevention programme (Neave et al., ).…”

Bacteriological etiology and treatment of mastitis in Finnish dairy herds

“…Our second aim was to study treatment and culling records for the cows in the study herds collected from the databases of the Finnish dairy herd recording system. Detailed analysis of the relationships between pathogen-specific IMI and different cow- and herd-specific factors are presented in Taponen et al [25]. The present study provides information about a PCR assay used for routine microbiological diagnostics of mastitic milk samples.…”