Effect of preculture freezing and incubation on bacteriological isolation from subclinical mastitis samples

Effects of a mastitis treatment strategy with or without on-farm testing

The etiology of mastitis is crucial information to use antimicrobials prudently for control and treatment. This study aimed to evaluate the effects of mastitis diagnosis and treatment strategies with on-farm testing, on cure, new intramammary infections (IMI), somatic cell count (SCC), and antimicrobial use, compared with farmers' current diagnosis and treatment strategies. The on-farm tests used, CHROMagar Mastitis (CHROMagar, Paris, France) and Minnesota Easy Culture System II Tri-plate (University of Minnesota, St. Paul, MN), both had etiological groups of IMI as result, being gram-positive growth, gram-negative growth, or culture negative. Two randomized controlled trials were conducted on 15 herds: trial 1 prospectively enrolled 155 cows with clinical mastitis, and trial 2 cross-sectionally included 78 cows with subclinical mastitis. In both trials, cows were randomly distributed over 3 equal-sized groups: a test group using CHROMagar, a test group using Minnesota, and a control group not using on-farm tests. Farmers decided whether or not to treat, and which antimicrobial treatment would be applied, using information available on the day of enrollment (control group), complemented with the on-farm test result 1 d after enrollment (both test groups). For clinical mastitis, an antimicrobial treatment was given in 58% of cases that used CHROMagar, in 80% that used Minnesota, and in 86% of the controls. For subclinical mastitis, an antimicrobial treatment was given in 50% of cases that used CHROMagar, in 54% that used Minnesota, and in 4% of the controls. Bacteriological cure rate of clinical mastitis was lowest in the CHROMagar group [odds ratio 0.18 (95%CI 0.03-0.99)] compared with the controls. Using the Minnesota on-farm test for subclinical mastitis diagnosis and treatments resulted in fewer new IMI on d 21 [odds ratio 0.06 (95%CI 0.00-0.74)] compared with the controls. Clinical cure rate, percentage of new IMI, and SCC on d 21 of clinical mastitis were comparable among the groups. Using on-farm tests in farmers' decision-making process resulted in more treatments in accordance with the etiology of mastitis than without on-farm testing. A diagnosis and treatment strategy with on-farm testing is advised in cows with clinical mastitis to enhance prudent antimicrobial use. For subclinical mastitis, however, on-farm testing may lead to an unacceptable increase in use of antimicrobials and thus should not be advised as the common approach.

Knowledge gaps and research priorities in Staphylococcus aureus mastitis control

This study assessed knowledge gaps and suggested research priorities in the field of Staphylococcus aureus mastitis. Staphylococcus aureus infecting the mammary gland remains a major problem to the dairy industry worldwide because of its pathogenicity, contagiousness, persistence in the cow environment, colonization of skin or mucosal epithelia, and the poor curing efficacy of treatments. Staphylococcus aureus also constitutes a threat to public health due to food safety and antibiotic usage issues and the potential for bidirectional transmission of strains between humans and dairy animals (cows and small ruminants). Gaps have been identified in (i) understanding the molecular basis for pathogenesis of S. aureus mastitis, (ii) identifying staphylococcal antigens inducing protection and (iii) determining the cell-mediated immune responses to infection and vaccination. The recommended priorities for research are (i) improved diagnostic methods for early detection of infection and intervention through treatment or management, (ii) development of experimental models to investigate the strategies used by S. aureus to survive within the mammary gland and resist treatment with anti-microbials, (iii) investigation of the basis for cow-to-cow variation in response to S. aureus mastitis, (iv) identification of the immune responses (adaptive and innate) induced by infection or vaccination and (v) antibacterial discovery programmes to develop new, more effective, narrow spectrum antibacterial agents for the treatment of S. aureus mastitis. With the availability and ongoing improvement of molecular research tools, these objectives may not be out of reach in the future.

Efficacy of recombinant bovine epidermal growth factor in the treatment of experimental subclinical Staphylococcus aureus mastitis in a ewe model

Staphylococcus aureus is the most common contagious mastitis pathogen of dairy cattle. Antimicrobial treatment of infected cattle results in variable cure rates. Epidermal growth factor (EGF) plays an important role in the modulation of host innate immune responses and the regulation of mammary epithelial regeneration, indicating that EGF may be useful as a treatment for mastitis. A pilot study was conducted to evaluate the efficacy of recombinant bovine EGF (rbEGF) for the treatment of S aureus intramammary infection (IMI) using an ovine model. Each ewe was experimentally infected with S aureus in both udder halves. One udder half of each ewe received one of two treatments: EGF (n=13) or pirlimycin (n=13). The contralateral udder half of each ewe received sterile saline as a control. The bacteriological cure rate following rbEGF was significantly lower (15 per cent) than that attained with pirlimycin hydrochloride (61 per cent) and did not differ from that following treatment with sterile saline. Cure rates following treatment with rbEGF were not significantly different to those following sterile saline. Given that EGF is associated with modulation of host immunity and wound healing, future studies into EGF should not focus on whether EGF increases cure rates of S aureus IMI.

Development of a loop-mediated isothermal amplification assay for the detection of Streptococcus agalactiae in bovine milk

Streptococcus agalactiae is a well-characterized bovine mastitis pathogen that is known to be highly contagious and capable of spreading rapidly in affected dairy herds. Loop-mediated isothermal amplification (LAMP) is a novel molecular diagnostic method that has the capability to provide rapid, cost-effective screening for pathogens to support on-farm disease control and eradication programs. In the current study, a LAMP test was developed to detect S. agalactiae in milk. The assay was validated on a bank of existing clinical mastitis milk samples that had previously been identified as S. agalactiae positive via traditional microbiological culture techniques and PCR. The LAMP assay was conducted on bacterial colonies and DNA extracted from milk in tube- and plate-based formats using multiple detection platforms. The 1-h assay conducted at 64 °C exhibited repeatability (coefficient of variation) of 2.07% (tube) and 8.3% (plate), sensitivity to ~20 pg of extracted DNA/reaction, and specificity against a panel of known bacterial mastitis pathogens. Of the 109 known S. agalactiae isolates assessed by LAMP directly from bacterial cells in culture, 108 were identified as positive, in accordance with PCR analysis. The LAMP analysis from the corresponding milk samples indicated that 104 of these milks exhibited a positive amplification curve. Although exhibiting some limitations, this assay provides an opportunity for rapid screening of milk samples to facilitate on-farm management of this pathogen.

Nutritional and hygienic quality of raw milk in the mid-northern region of Algeria: correlations and risk factors

This paper aims to study the overall quality of raw milk in the mid-northern region of Algeria. The analysis results showed a decrease in the average temperature for the delivery of 1,54°C with P<0.001. However, no significant variation (P>0.05) was observed in almost all the physical and nutritional parameters studied (pH, fat content, and protein content) between M1 and M2. The average contamination by total mesophilic aerobic bacteria (TMAB), coliforms, yeasts, molds, and different pathogens in samples taken at M1 showed significant changes at M2. This was confirmed by the decrease of reduction time of methylene blue (RTMB), about 54%. The variation was described as follows: (P>0.05) for yeasts and (P<0.05) for molds in M1 and M2, (P<0.05) for TMAB in M1, and (P<0.001) for TC, FC, and TMAB in M2. The analysis for the detection of Salmonella spp. showed no contamination in all samples tested, while antibiotic residues were detected in 35% of milks delivered. In conclusion, several risk factors have been identified in this study, namely, the effect of the season and the distance between the farm and the dairy unit.

Evaluation of a culture-based pathogen identification kit for bacterial causes of bovine mastitis

Accurate identification of mastitis-causing bacteria supports effective management and can be used to implement selective use of antimicrobials for treatment. The objectives of this study were to compare the results from a culture-based mastitis pathogen detection test kit ('VetoRapid', Vétoquinol) with standard laboratory culture and to evaluate the potential suitability of the test kit to inform a selective treatment programme. Overall 231 quarter milk samples from five UK dairy farms were collected. The sensitivity and specificity of the test kit for the identification of Escherichia coli, Staphylococcus aureus, coagulase-negative staphylococci, Streptococcus uberis and Enterococcus spp. ranged from 17 per cent to 84 per cent and 92 per cent to 98 per cent, respectively. In total, 23 of 68 clinical samples were assigned as meeting the requirement for antimicrobial treatment (Gram-positive organism cultured) according to standard culture results, with the test kit results having sensitivity and specificity of 91 per cent and 78 per cent, respectively. Several occurrences of misidentification are reported, including S. aureus being misidentified as coagulase-negative staphylococci and vice versa. The test kit provides rapid preliminary identification of five common causes of bovine mastitis under UK field conditions and is likely to be suitable for informing selective treatment of clinical mastitis caused by Gram-positive organisms.

Events occurring during the previous lactation, the dry period, and peripartum as risk factors for early lactation mastitis in cows receiving 2 different intramammary dry cow therapies

The objective of this study was to investigate the association between mastitis events occurring during the previous lactation, the dry period, and the peripartum period on the incidence of early lactation mastitis in cows receiving ceftiofur hydrochloride or penicillin dihydrostreptomycin as intramammary dry cow antibiotic therapy. Cows (n=402) from 2 large dairy farms in Central Florida were enrolled in the study at the time of dry-off processing and were randomly assigned to 1 of 2 dry cow therapies: ceftiofur hydrochloride or penicillin dihydrostreptomycin. Composite milk samples were collected at dry-off and after calving for bacteriological examination and somatic cell count. Peripartal health disorders were monitored during the first 30 d of lactation and included calving difficulty, metritis, ketosis, and left displaced abomasum. Milk production and individual somatic cell scores (SCS) were recorded monthly by the Dairy Herd Improvement Association. The main outcome variables were the risk of clinical mastitis during the first 30 and 60 d of lactation, and the risk of subclinical mastitis at the first 2 monthly Dairy Herd Improvement Association tests after calving (up to 70 d in milk). Additionally, the SCS and the presence of mastitis pathogens in milk at dry-off and at calving were analyzed. Explanatory variables consisted of events occurring during the previous lactation, at dry-off and during the dry period, at calving, and within the first 30 d after calving. Multiple events occurring during the previous lactation had a significant effect on the incidence of mastitis in the subsequent lactation. These events included low milk yield, intermediate lactation length, clinical mastitis, and lactation SCS average. Similarly, intramammary infections with environmental bacteria at dry-off increased the chances of clinical mastitis the first month after calving. Dry-off therapy had a significant effect on mastitis incidence; cows treated with ceftiofur hydrochloride had lower odds of having clinical and subclinical mastitis in the subsequent early lactation compared with cows treated with penicillin dihydrostreptomycin.

Comparing effects of freezing at -196 °C and -20 °C on the viability of mastitis pathogens

The aim of this study was to compare the effects of cryopreservation at approximately -196 °C in liquid nitrogen (N) and freezing at approximately -20 °C in a freezer, on the viability and survival of eight different mastitogenic bacteria inoculated in milk. Bacteria were frozen at approximately -20 °C in a freezer and cryopreserved at approximately -196 °C in liquid nitrogen. An effective preservation method was needed for follow-up samples from cows identified in the South African National Milk Recording Scheme (NMRS) with somatic cell counts above 250 000 cells/mL milk. The organisation responsible for sample collection of the NMRS milk samples also provides producers with liquid nitrogen for their semen flasks at the collection sites. This existing mode of storage and transport could therefore be utilised.Ten samples of each organism were thawed and cultured bi-weekly until week 18 for both temperature treatments. An additional sampling was performed at week 30 for samples frozen at approximately -20 °C. Freezing and cryopreservation did not impair subsequent isolation of Streptococcus dysgalactiae, Streptococcus uberis, Enterococcus faecalis, Staphylococcus aureus (STH) (phage type lytic group III) or Sta. aureus (STA) (phage typed, other than lytic group III). Survival was indicated by the isolation of bacteria from samples, and viability by the strength of growth of the bacteria isolated. The survival of Streptococcus agalactiae decreased after week 12 and Escherichia coli after week 16 of freezing, but both organisms survived under cryogenic preservation until week 18. Coagulase-negative staphylococci survived until week 18 for both freezing and cryogenic preservation.Both storage methods could thus contribute to the improvement of a pro-active approach towards udder health management in South African dairy herds.

Reservoirs of Staphylococcus aureus in meat sheep and dairy cattle

The objective of the study was to investigate reservoirs and transmission of S. aureus in ewes and lambs in 3 meat sheep flocks. Repeated sampling of milk, teat skin, nasal- and vaginal mucous membranes was performed and samples were analysed for S. aureus. For comparison, samples were also collected from cows and young heifers in 3 dairy cattle herds. Selected isolates were compared by pulsed-field gel electrophoresis (PFGE). S. aureus was detected in 8 (1.5%) of 520 milk samples from ewes and in 38 (6.4%) of 588 milk samples from cows. From body site swabs, S. aureus was found in 394 (32.6%) of 1208 samples from sheep and in 67 (16.0%) of 420 samples from cattle. The proportion of S. aureus-positive nasal swabs from ewes and cows were 56.7% and 13.9%, respectively. From lambs, 58.2% of the nasal swabs were S. aureus-positive. In each flock, one S. aureus pulsotype predominated. Identical S. aureus pulsotypes were found in milk and from body sites. Paired S. aureus isolates from the nasal cavity of (i) ewes and their lambs, (ii) twins and (iii) from repeated swabs of individual ewes were compared by PFGE, and in the majority of cases the two isolates were identical. The results contribute new knowledge indicating frequent transmission of S. aureus between the dam and her lambs and within animals in a flock. In contrast to cattle, S. aureus is frequently present in the nose of sheep which may represent the primary reservoir of S. aureus in sheep flocks.

The National Cohort of Dairy Farms--a data collection platform for mastitis research in Canada

Costs and feasibility of extensive sample collection and processing are major obstacles to mastitis epidemiology research. Studies are often consequentially limited, and fundamental mastitis researchers rarely have the opportunity to conduct their work in epidemiologically valid populations. To mitigate these limitations, the Canadian Bovine Mastitis Research Network has optimized research funds by creating a data collection platform to provide epidemiologically meaningful data for several simultaneous research endeavors. This platform consists of a National Cohort of Dairy Farms (NCDF), Mastitis Laboratory Network, and Mastitis Pathogen Culture Collection. This paper describes the implementation and operation of the NCDF, explains its sampling protocols and data collection, and documents characteristics, strengths and limitations of these data for current and potential users. The NCDF comprises 91 commercial dairy farms in 6 provinces sampled over a 2-yr period. Primarily Holstein-Friesian herds participating in Dairy Herd Improvement milk recording were selected in order to achieve a uniform distribution among 3 strata of bulk tank somatic cell counts and to reflect regional proportions of freestall housing systems. Standardized protocols were implemented for repeated milk samplings on clinical mastitis cases, fresh and randomly selected lactating cows, and cows at dry-off and after calving. Just fewer than 133,000 milk samples were collected. Demographic and production data were recorded at individual cow and farm levels. Health management data are documented and extensive questionnaire data detailing farm management and cleanliness information are also captured. The Laboratory Network represents coordinated regional mastitis bacteriology laboratories using standardized procedures. The Culture Collection archives isolates recovered from intramammary infections of cows in the NCDF and contains over 16,500 isolates, all epidemiologically cross-referenced between linked databases. The NCDF is similar to Canadian dairies in relation to mean herd size, average production, and freestall percentages. Pathogen recovery was greater than anticipated, particularly for coagulase-negative staphylococci and Corynebacterium spp. International scientists are encouraged to use this extensive archive of data and material to enhance their own mastitis research.

Diagnosis of intramammary infection in samples yielding negative results or minor pathogens in conventional bacterial culturing

Up to half of quarter milk samples submitted for mastitis diagnosis are culture-negative results or lead to identification of coagulase-negative staphylococci or Corynebacterium bovis in conventional culturing, the so-called minor pathogens. The interpretation and usefulness of these results in terms of udder and animal health management is limited, even though the amount of resources spent is relatively high. This work aimed to test two methods of analysis of milk samples with the goal of increasing detection of intramammary pathogens. In the first study, 783 milk samples were processed in duplicate: before and after freezing at -20°C for 24 h, using standard bacteriological techniques. There was a significant difference between the two methods with samples frozen for 24 h yielding significantly fewer Gram-positive catalase-positive cocci, Gram-negative bacilli, Gram-positive bacilli and significantly more samples leading to no growth, than samples before freezing. The number of samples yielding Gram-positive catalase-negative cocci was not significantly affected by freezing. In the second study, a real-time PCR-based test was performed on milk samples with an individual quarter somatic cell count above 500,000 cells/ml that were either negative (n=51 samples) or that led to the isolation of minor pathogens in culturing: Corynebacterium bovis (n=79 samples) or non-aureus staphylococci (NAS, n=32). A mastitis pathogen, beyond the result obtained with standard bacteriology, was detected on 47% of the no-growth samples, on 35% of the samples from which C. bovis had been isolated and on 25% of the samples from which NAS had been isolated. The most commonly detected major pathogen was Escherichia coli, followed by Streptococcus uberis, Arcanobacterium pyogenes/Peptoniphilus indolicus and Streptococcus dysgalactiae. These results suggest that simply freezing milk samples for 24 h does not increase the detection of intramammary bacteria in milk samples and therefore should not be recommended. However, use of the real-time PCR-based test may be useful in diagnosing intramammary infections when milk samples with high somatic cell counts are culture-negative or when culturing results in the detection of minor pathogens.

Predictors for successful bacteriological culture from milk samples

A total of 757 milk samples were taken from 57 farms throughout Wales as part of a mastitis investigation. Problem cows were selected using the most recent milk recording or, if these data were unavailable, the whole herd was assessed using the California mastitis test (CMT) and scored on a scale of 0 to 3. The affected quarter was identified using CMT. The results of the bacteriology were grouped into negative and positive culture. All contaminated samples were excluded. The CMT recording at the time of sampling, the infection status of the cow (new, first, chronic or repeat) as defined by national milk records and the number of quarters infected at the time of sampling were identified for negative and positive samples. Selecting quarters with a higher CMT score increased the likelihood of positive culture. Culturing from a sample with a CMT score of 3 was over three times more likely to yield a positive culture than a score of 1 (odds ratio [OR] 3.74, 95 per cent confidence interval [CI] 1.41 to 9.97) and 1.7 times more likely to yield a positive culture than a score of 2 (OR 1.70, 95 per cent CI 1.16 to 2.50). Culturing from a score of 2 was not statistically different from a score of 1 in terms of the likelihood that a positive culture would be identified (OR 2.20, 95 per cent CI 0.83 to 5.93). There was no statistically significant difference in the proportion of negative samples when comparing chronic, repeat, new and first infections or number of quarters infected.

The use of data from sampling for bacteriology for genetic selection against clinical mastitis

One breeding objective of Dutch cattle breeders is to improve genetic resistance against clinical and subclinical mastitis. Because of a lack of direct mastitis information, udder health breeding values are based on indirect traits. Inclusion of direct information on clinical mastitis could improve reliability of breeding values. The aim of this study was to investigate whether data from milk samples sent in for bacteriology are potential sources of information for the occurrence of mastitis, which may be used in animal breeding, and if so how this data can be used. Although there are 2 separate flows of milk samples for bacteriology in the Netherlands, it was not considered necessary to account for the origin of the samples. In both flows, the majority of the samples are visually normal and flow-specific traits are highly correlated. Therefore, information from these flows is combined for genetic analysis. Nearly two-thirds of the bacteriology data could be linked to milk recording and pedigree records. Relatively few farmers (<3%) took 5 or more samples for bacteriology between January 1, 2003, and March 31, 2006. Their herds had, on average, greater milk production and lower cell counts than herds for which no samples were taken. However, the range and variation within both groups of herds for these variables was similar and there was a large overlap in sires used within both groups. Whether or not samples were taken for bacteriology turned out to be a potentially useful indicator for clinical mastitis at the cow level, because this trait had a strong positive genetic correlation with clinical mastitis registered by farmers (0.84 or 0.89, depending on the data set) and similar heritability (2%) and genetic variation. Also, genetic correlations of bacteriology with SCC traits were similar to those for farmer-registered clinical mastitis. An important advantage of these bacteriology data is that they are already collected routinely and stored in a central database in the Netherlands; this is not the case for registration of clinical cases. Thus, data from bacteriological culturing can be used for genetic improvement of udder health.

Invited Review: The Role of Cow, Pathogen, and Treatment Regimen in the Therapeutic Success of Bovine Staphylococcus aureus Mastitis

Staphylococcus aureus is an important cause of udder infections in dairy herds. Both lactational and dry cow therapy are part of Staph. aureus control programs. Reported cure rates for Staph. aureus mastitis vary considerably. The probability of cure depends on cow, pathogen, and treatment factors. Cure rates decrease with increasing age of the cow, increasing somatic cell count, increasing duration of infection, increasing bacterial colony counts in milk before treatment, and increasing number of quarters infected. Staphylococcus aureus mastitis in hind quarters has a low cure rate compared with front quarters. Antimicrobial treatment of intramammary infections with penicillin-resistant Staph. aureus strains results in a lower cure rate for treatment with either beta-lactam or non-beta-lactam antibiotics. Other strain-specific factors may affect the probability of cure but routine diagnostic methods for use in bacteriology laboratories or veterinary practices are not yet available. The most important treatment factor affecting cure is treatment duration. Increased duration of treatment is associated with increased chance of cure. Economically, extended treatment is not always justified, even when indirect effects of treatment such as prevention of contagious transmission are taken into consideration. Usefulness of treatment trials could be improved by standardization of case definitions, consideration of host and strain factors, and sufficient statistical power. Treatment of young animals with penicillin-sensitive Staph. aureus infections is often justified based on bacteriological cure and economic outcome, whereas treatment of older animals, chronic infections, or penicillin-resistant isolates should be discouraged.

Evaluation of Petrifilm for the isolation of Staphylococcus aureus from milk samples

Four experiments were conducted to evaluate the Petrifilm Staph Express Count plate (3M, Minneapolis, MN) for diagnosis of mastitis caused by Staphylococcus aureus. The objective of experiment 1 was to determine the sensitivity of Petrifilm compared with results of standard and augmented microbiological techniques, and the objective of experiment 2 was to compare microbiological results of composite and quarter milk samples processed using Petrifilm. Experiment 3 was conducted to determine the specificity of the Petrifilm method based on different interpretation parameters, and the objective of experiment 4 was to determine the repeatability of reading Petrifilm Staph Express plates. Results of standard microbiological techniques used for experiments 1 and 2 were compared with results of samples preprocessed using centrifugation or preincubation. The prevalence of recovery of Staph. aureus from milk samples processed using Petrifilm was significantly greater than the prevalence of milk samples processed using standard microbiological techniques. The sensitivity of isolation of Staph. aureus was 65.6, 75.0, 84.4, and 87.5% for standard, centrifugation, incubation, and Petrifilm methods, respectively. The occurrence of a distinct pink zone surrounding a colony was highly specific for Staph. aureus, and the specificity was 98.5 and 96.0% for experiments 3 and 4, respectively. The use of a weak pink zone to diagnose Staph. aureus resulted in a high rate of false-positive results. The interpretation of results of Petrifilm Staph Express was associated with the person that read the plates. Results from all 4 experiments indicate potential for the Petrifilm products as a diagnostic tool in some herd situations when Staph. aureus is the pathogen of interest. Results also indicate the need for standardization of interpretive criteria for personnel working with the products.

Quantification of Staphylococcus aureus in unpasteurised bovine and caprine milk by real-time PCR

A sensitive and reproducible real-time PCR assay targeting the nuc gene of Staphylococcus aureus was applied for quantification of this microorganism in artificially and naturally contaminated raw milk samples. The S. aureus cell equivalents (SCEs) estimated by the real-time PCR method were two log scales higher than colony forming units (CFUs) estimated from a plate count method in artificially contaminated milk. The repeatability of the real-time PCR assay including the DNA isolation procedure was assessed by analysing the data derived from naturally contaminated samples. The relative standard deviation of the log-transformed data of four real-time PCR measurements including duplicate DNA isolations ranged between 11.3 and 1.0%. When analysing 80 bovine and 107 caprine naturally contaminated raw milk samples, the real-time PCR method yielded 19.3% more positive samples than the plate count method. With the exception of one sample, SCEs were always higher than CFUs. The difference between SCEs and CFUs was highly variable, and it was not possible to correlate real-time PCR-derived SCEs and CFUs. However, as each SCE detected by real-time PCR indicates a S. aureus cell, which is or has been present in the sample, this method offers the advantage of a retrospective analysis even of processed samples to aid food poisoning-related risk assessment.

Bulk-tank milk analysis. A useful tool for improving milk quality and herd udder health

Bulk-tank milk (BTM) analysis is now widely accepted as a useful tool for evaluating milk quality and monitoring udder-health status in a herd. Bacterial and somatic cell count (SCC) estimation of BTM, when done repeatedly over a period of time, can become a significant knowledge base. When interpreted within the context of the farm's management practices, this information provides a basis for evaluating current and potential milk quality and mastitis problems in a herd. This article describes the process of using BTM analysis to make decisions on improving milk quality and herd udder health. It should be kept in mind that although individual cow samples for milk culture and SCC are more definitive for diagnosis and monitoring of udder health, BTM analysis is less expensive, more convenient, and faster than testing milk samples from individual animals or groups of cows.