We inoculated pasteurized whole milk with Escherichia coli strains GC4468 (intact marRAB locus), JHC1096 (Δ marRAB), or AG112 (Δ marR), and incubated each overnight at 37°C. All strains were then recovered from the milk cultures, and susceptibilities to antimicrobial agents were determined by the E-test strip method (CLSI). Cells of strain GC4468, prior to culturing in milk, were susceptible to trimethoprim, gatifloxacin, cefotaxime and tetracycline. After culturing GC4468 in pasteurized milk, however, the minimal inhibitory concentrations (MICs) increased 1·4-fold for trimethoprim (P⩽0·05), 1·5-fold for gatifloxacin (P⩽0·05), 2·0-fold for cefotaxime (P=0·008), and 1·4-fold for tetracycline (P⩾0·05). After culturing GC4468 on milk count agar the MICs were enhanced 3·4-fold for trimethoprim (P⩽0·05), 10-fold for gatifloxacin (P=0·001), 7·1-fold for cefotaxime (P=0·011), and 40·5-fold for tetracycline (P=0·074), but exhibiting tetracycline resistance with a mean MIC of 74·7±18·47 μg/ml (CLSI). The MICs of the antimicrobial agents for JHC1096 cells after culturing in pasteurized whole milk were indistinguishable (P⩾0·05) from baseline MICs measured before culturing in the same type of milk. Thus, Esch. coli cells harbouring the marRAB locus exhibit reduced susceptibilities to multiple antimicrobial agents after culturing in pasteurized whole milk.

Interest in selective dry cow therapy (SDCT) has been increasing owing to concerns over development of antimicrobial resistance. Implementation of SDCT, however, requires a quick and cost-effective on-farm method for identifying cows for treatment and cows that can be left without treatment. The objective of the present study was to evaluate the use of clinical mastitis (CM) history and somatic cell counts (SCC) from monthly Dairy Herd Improvement (DHI) records in identification of infected and uninfected cows at dry-off. A total of 647 Holstein cows were classified as uninfected or infected at dry-off based on CM history and varying number of monthly SCC records (with three different SCC cut-offs). Cows were considered uninfected based on the following criteria: (1) SCC <100 000 cells/ml and no CM during the lactation; (2) SCC <200 000 cells/ml and no CM during the lactation; (3) as criterion two, but additionally a cow was also considered uninfected if it experienced a case of CM during the first 3 months of the lactation and the SCC was <100 000 cells/ml for the rest of the lactation; (4) SCC <300 000 cells/ml and no CM during the lactation; otherwise they were considered infected. Infected and uninfected cows at dry-off were most efficiently identified using three months' SCC records with a threshold of 200 000 cells/ml for cows without CM during the lactation and a threshold of 100 000 cells/ml during the rest of lactation for cows with CM during the first 90 days in milk. Moreover, this criterion also most efficiently identified cows infected with major pathogens only at dry-off. The success of the criteria used for identifying infected and uninfected cows will, however, depend on herd characteristics, such as prevalence of infection and type of pathogens present in the herd.

Milk culture results at approximately 6 d post calving were assessed in a 2-year retrospective single-cohort study in 178 Norwegian herds. A combined teat dipping and selective antibiotic therapy trial was performed in these herds where cows with composite milk somatic cell count (CMSCC) >100 000 cells/ml before drying-off (geometric mean of the last three CMSCC test-days) and isolation of Staphylococcus aureus or Streptococcus dysgalactiae were selected for either short-acting lactation antibiotic treatment or long-acting dry cow antibiotic treatment. Milk culture results at approximately 6 d post-calving were available from 437 treated cows and 3061 non-treated cows before drying-off and separate multivariable logistic regression models were ran for these two groups. Risk factors associated with isolation of Staph. aureus 6 d post calving for non-treated cows were CMSCC >400 000 cells/ml before drying-off v. <400 000 cells/ml (Odds ratio (OR)=2·4) and clinical mastitis (CM) in the previous lactation v. non-treated (OR=1·5). Risk factors associated with Staph. aureus 6 d post calving for treated cows was a CMSCC >200 000 cells/ml before drying-off v. <200 000 cells/ml (OR=2·3) and CM in the previous lactation versus non-treated (OR=1·7). For non-treated cows it was 1·7-times more likely to isolate Str. dysgalactiae 6 d post-calving if the CMSCC was >50 000 cells/ml compared with <50 000 cells/ml. For treated cows it was 3·7–5·8-times more likely to isolate Str. dysgalactiae 6 d post calving if given short-acting lactation formula at quarter level compared with long-acting dry cow formula used at cow level. Regular use of iodine post-milking teat disinfection (PMTD) did not influence the isolation of Staph. aureus 6 d post calving, but it was less likely to isolate Str. dysgalactiae 6 d post calving if iodine PMTD was used regularly rather than irregularly. The external teat sealant had no effect on either of the two bacteria.

This study indicates that the CMSCC limit for sampling cows before drying-off can be reduced to 50 000 cells/ml in herds with a Str. dysgalactiae problem. Iodine PMTD should also be recommended in these herds. Cows with a CMSCC >400 000 cells/ml prior to drying-off should receive long-acting dry cow formula irrespective of the milk culture result.

A treatment containing a live food-grade organism, Lactococcus lactis DPC3147, was compared with conventional antibiotic therapy for its potential to treat bovine chronic subclinical or clinical mastitis in two separate field trials. Effects on disease symptoms and bacteriology were monitored in response to infusion with the culture in each trial. In the first trial, the live culture treatment was compared with an intramammary antibiotic (n=11 quarters for each treatment). Results from this small trial demonstrated that the live culture had potential to be as effective at eliminating chronic subclinical infections as an antibiotic treatment. By day 12, 7 of the 11 quarters treated with the live culture were pathogen-free compared with 5 of the 11 antibiotic-treated infected quarters. Somatic cell counts (SCC) remained relatively unchanged regardless of treatment: average log SCC pre- and post-treatment in the lactococci-treated group were 6·33±0·41 (day 0) and 6·27±0·43 cells/ml (day 12) and average log SCC pre- and post-treatment in the antibiotic-treated group were 6·34±0·37 and 6·22±0·46 cells/ml on day 0 and on day 12, respectively. In the second trial, the live culture was compared with an intramammary antibiotic for the treatment of naturally occurring clinical mastitis cases (n=25 quarters for each treatment). Following a 14-d experimental period, similar bacteriological responses were observed in 7 out of 25 live culture treated quarters and 9 out of 25 antibiotic-treated quarters. Additionally, 15 of 25 cases treated with the culture and 18 of 25 cases treated with the antibiotic did not exhibit clinical signs of the disease following treatment. The results of these trials suggest that live culture treatment with Lc. lactis DPC3147 may be as efficacious as common antibiotic treatments in some instances.

Inflammatory bowel disease (IBD; Crohn′s disease and ulcerative colitis) is the clinical outcome of three interactive pathogenic factors: genetic susceptibility, environmental triggers and immune dis-regulation. At present, only the immune response is targeted by most therapeutic or preventive strategies. The beneficial effect of yoghurt on health as well as its immunomodulator effect on the gut immune system is well documented. The aim of this work was to study the possible beneficial effects of yoghurt consumption on an experimental model of IBD in mice. Balb/c mice were fed with yoghurt for 10 consecutive days. At the end of the feeding period the mice received three inoculations of 2, 4, 6-trinitrobenzene sulphonic acid (TNBS) solutions once a week for 3 consecutive weeks. After TNBS instillation the mice received yoghurt again for 10 consecutive days. IBD control received only TNBS. After treatments we analysed the number of IgA–secreting cells, CD4+, CD8+ T cells population and the number of apoptotic cells in the large intestine. The number of erythrocytes and leucocytes in peripheral blood mononuclear cells (PBMCs) was also determined. We demonstrated the antinflammatory effect of yoghurt in an experimental model of IBD induced by TNBS. The effect was mediated by an increase in the number of the IgA+cells, a decrease in CD8+ population and by the induction of apoptosis of the infiltrative cells in the large intestine.

N-Chlorotaurine (NCT) is a promising endogenous agent for topical treatment of infections. We tested the tolerability and pharmakokinetics of NCT in the bovine mammary glands in a phase 1 study. Three concentrations of NCT in water (0·1%, 1·0%, 2·0%) were administered intramammarily in each of two cows. Into two quarters of the udder 100 ml NCT was injected into each twice daily for 5 d, while 0·9% NaCl was injected into the other two quarters in a randomized and blinded manner. Samples of milk were taken to determine the number of leucocytes and the activity of NCT, and samples of urine and blood to determine the taurine and chloride concentration. Chloride concentrations in serum samples were determined by an ISE-Unit of a Modular-System of the Roche Diagnostics company. The udder was monitored clinically for signs of inflammation. Oxidative activity could be detected in the milk after single irrigations for 15 min (0·1% NCT) and for maximally 5 h (1% and 2% NCT), respectively. On day 2, leucocytes increased to 4×106/ml in the NCT group, while they remained ⩽1×106/ml in the saline group. However, on days 3–5 they increased to (5–7)×106 in both the NCT and control group without any statistical difference. One day after the end of dosing the number decreased significantly and reached the baseline (<1×106/ml) on day 10. The decrease was similar in both groups. Except for sporadic slight induration of single quarters in both groups and slight reduction of milk performance no disorders occurred. Taurine levels in blood and urine did not change. Irrigation of the bovine mammary gland with both NCT and saline caused a transient increase of leucocytes in the milk, but no severe side effects. The absence of residues and decay products may be a great advantage of NCT over other antimicrobial agents.

In the accompanying article, we demonstrated that a live culture of Lactococcus lactis compares favourably with antibiotics for treatment of bovine mastitis in two initial field trials. In an effort to explain the mechanism involved, this study investigated the effect of culture administration on the local immune response. In this respect we initially observed that infusion of the live culture Lactococcus lactis stimulated substantial recruitment of polymorphonucleocytes (PMN) and lymphocytes to the udder. For instance, in one assay, quarters infused with the probiotic experienced a dramatic increase (~20 000-fold) in neutrophils over the first 48-h period from an average value of 83·6 cells/ml pre-treatment to 1·78×106 cells/ml 48 h post-infusion. Levels of the acute phase proteins haptaglobin and milk amyloid A were also elevated significantly in comparison with controls following infusion of the culture. The results of flow cytometric assays also demonstrated that while infusion of a live lactococcal culture led to an enhanced recruitment of PMN to the udder (from 1·85×104 cells/ml pre-infusion to 1·45×106 cells/ml 24 h post-infusion) cell-free supernatant from the same culture was not able to do so, indicating that live Lc. lactis can specifically trigger the mammary immune response to elicit PMN accumulation. These results suggest that the mechanism responsible for this probiotic treatment of mastitis is associated with stimulation of the host intramammary immune system.

This study describes a method for species-specific detection of animal DNA from different species (cattle, sheep, goat, water buffalo) in milk and dairy products. A primer set was designed in conserved region on the basis of the alignment of the sequence codifying the genomic κ-casein gene in order to amplify all four species with a single primer pair. Polymorphisms were detected via minisequencing with extension primers designed in conserved sequences for haplotype determination that allow unambiguous assignment to each species. The method was successfully applied to the detection of raw and pasteurized milk from the four different species considered as well as to cheese products from the retail trade. Estimation of the limit of detection was carried out using a progression of dilutions of genomic DNA as well as DNA isolated from milk of a known number of somatic cells from different species in order to be able to achieve detection rates as low as 0·1% bovine milk mixed with buffalo milk.

A model to calculate the economic losses of mastitis on an average Dutch dairy farm was developed and used as base for a tool for farmers and advisors to calculate farm-specific economic losses of mastitis. The economic losses of a clinical case in a default situation were calculated as €210, varying from €164 to €235 depending on the month of lactation. The total economic losses of mastitis (subclinical and clinical) per cow present in a default situation varied between €65 and €182/cow per year depending on the bulk tank somatic cell count. The tool was used to measure perception of the total economic losses of mastitis on the farm and the farmers' assessment of the cost factors of mastitis on 78 dairy farms, of which 64 were used for further analyses. Most farmers (72%) expected their economic losses to be lower than those revealed by our calculation made with their farm information. Underestimating the economic losses of mastitis can be regarded as a general problem in the dairy sector. The average economic losses assessed by the farmers were €78/cow per year, but a large variation was given, €17–198/cow per year. Although the average assessment of the farmers of the different cost factors is close to the default value, there is much variation. To improve the adoption rate of advice and lower the incidence of mastitis, it is important to show the farmers the economic losses of mastitis on their farm. The tool described in this paper can play a role in that process.

Mastitis is an inflammation of the mammary glands and in most cases it is caused by the presence of microorganisms. High mastitis rates in dairy cattle herds can cause an increase in total microorganism counts of bulk tank milk. The present paper was aimed at verifying whether the occurrence of mastitis in dairy cattle herds is reflected in raw-milk indicators of hygienic-sanitary quality. To observe the correlation among the analysed variables, we performed a logarithmical transformation (log10) of different indicator counts of raw milk and compared them with the occurrence of mastitis in dairy cattle herds. Few correlations were observed among mastitis cases in dairy cattle herds and the raw-milk indicators of hygienic-sanitary quality. We observed a negative correlation between the log10 of mesophilic aerobic plate counts and psychotropic aerobic plate counts when compared with the occurrence of no bacterial growth. The log10 of thermophilic aerobic plate counts and yeasts and mould aerobic plate counts presented a positive correlation with the cases of infectious mastitis and mastitis caused by Staphylococcus spp.