Pulsed-field gel electrophoresis and antimicrobial sensitivity testing were used as tools to investigate the epidemiology of Streptococcus uberis mastitis in dairy cows. A total of 62 different strains were found among 138 isolates from the four herds investigated, and between 10 and 26 different strains were found in each herd. There was no strain common to all four herds. Identical strains of S. uberis were detected from different quarters of individual cows and from cows within the same herd, suggesting that transmission from quarter to quarter and cow to cow had occurred. Despite the great variation in S. uberis strains, persistent infection with the same strain within a lactation was observed in most cows. Predominant strains were present in two herds. Preliminary investigations could not clarify why these particular strains might predominate, but in one herd there was a significant difference between the prevalence of clinical mastitis in quarters infected with the predominant strain and that in quarters infected with other strains, suggesting the greater virulence of the predominant strain. The wide variety of S. uberis strains found is consistent with an environmental source of S. uberis. However, evidence of direct transmission, the persistence of infection, and the predominance of particular strains in some herds indicate that S. uberis infections are epidemiologically complex and that the relative importance of these factors in the occurrence of mastitis may differ between herds.

To improve diagnosis of mastitis in dairy cattle, a multiplex polymerase chain reaction (PCR) assay was developed for the simultaneous detection of the four major bacterial causes of bovine mastitis, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, and Streptococcus uberis. The target sequence was the 16S to 23S rRNA spacer regions. The performance of the assay was examined with 117 milk samples collected from a subclinically infected herd, and the diagnostic specificities and sensitivities of the multiplex PCR were compared with conventional culture. PCR was significantly more sensitive than culture for detection of S. aureus and S. uberis, but there were no significant differences in sensitivities between PCR and culture for the detection of S. agalactiae and S. dysgalactiae. The results suggest that this multiplex PCR assay could be used as an alternative method in routine diagnosis for rapid, sensitive, and specific simultaneous detection of S. aureus, S. agalactiae, S. dysgalactiae, and S. uberis in milk samples.

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Effective diagnostic tools for screening herds for mastitis pathogens are important in development and monitoring of mastitis control programmes. A multiplex polymerase chain reaction (PCR) assay for simultaneous detection of Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae and Streptococcus uberis was used in preliminary studies to assess its applicability as an alternative method for monitoring mastitis caused by these organisms at the herd level. PCR was used to detect the presence of these organisms in bulk milk samples. Correlations with bulk milk somatic cell counts (BMCC), total bacteria counts and thermoduric bacteria counts were evaluated. A total of 176 bulk milk samples were collected from 42 herds on five consecutive occasions at approx. 10-d intervals. Str. uberis was the most common organism in these bulk milk samples. There was no relationship between presence of either Staph. aureus, Str. dysgalactiae or Str. uberis and BMCC, total bacteria counts or thermoduric bacteria counts. However, presence of Str. agalactiae was associated with high BMCC and total bacteria counts. The results of this study show that regular analysis of bulk milk using this multiplex PCR assay may be a useful tool for monitoring herd status with respect to Str. agalactiae, but is of less value for monitoring occurrence of Staph. aureus, Str. dysgalactiae and Str. uberis. Further investigations are needed to clarify the relationship between positive PCR results and the prevalence of infected cows in the herd.

No abstract

One of the major challenges for dairy producers is to produce, harvest, and store high-quality colostrum and feed it to their replacement heifer calves. Limited published data are available in Australia regarding the relationship between colostrum management, hygiene, and quality. The objectives of this study were to investigate (1) the colostrum storage and handling practices carried out on farm; (2) the immunoglobulin concentration and bacterial composition of colostrum being fed to replacement dairy heifer calves; (3) the percentage of colostrum being fed to replacement dairy heifer calves that meet industry recommendations; and (4) risk factors for bacterial contamination of colostrum. The study was carried out on 24 dairy farms located near Rochester, Victoria, Australia. Two hundred forty colostrum samples were collected (10 samples per farm). Each farm harvested and stored first-milking colostrum under normal farm conditions. A 10-mL sample of the colostrum was collected in a sterile container immediately before feeding, and a Brix refractometer reading was taken. The samples were then frozen at -4°C and submitted for bacterial concentration analysis. Fifty-eight percent of colostrum samples met the recommended industry standard of a total plate count (TPC) of <100,000cfu/mL, and 94% of colostrum samples met the recommended industry standard of total coliform count (TCC) of 10,000cfu/mL. However, when all the current industry recommendations for TPC, TCC, and Brix refractometer percentage for colostrum quality were considered, only 23% of the samples met all standards. These findings demonstrate that a large number of calves were at risk of receiving colostrum of poor quality, with high bacterial loads that may have interfered with the acquisition of transfer of passive immunity and affected calf health. Further investigation is required to identify the farm-specific factors that may influence the level of bacterial contamination of colostrum. Recommendations as a result of this study include refrigeration of excess colostrum shortly (within 1h) after collection and thorough disinfection of the calf feeding apparatus before use.

Automated walk-over weighing systems can be used to monitor liveweights of cattle. Minimal literature exists to describe agreement between automated and static scales, and no known studies describe repeatability when used for daily measurements of dairy cows. This study establishes the repeatability of an automated walk-over cattle-weighing system, and agreement with static electronic scales, when used in a commercial dairy herd to weigh lactating cows. Forty-six lactating dairy cows from a seasonal calving, pasture-based dairy herd in southwest Victoria, Australia, were weighed once using a set of static scales and repeatedly using an automated walk-over weighing system at the exit of a rotary dairy. Substantial agreement was observed between the automated and static scales when assessed using Lin's concordance correlation coefficient. Weights measured by the automated walkover scales were within 5% of those measured by the static scales in 96% of weighings. Bland and Altman's 95% limits of agreement were -23.3 to 43.6 kg, a range of 66.9 kg. The 95% repeatability coefficient for automated weighings was 46.3 kg. Removal of a single outlier from the data set increased Lin's concordance coefficient, narrowed Bland and Altman's 95% limits of agreement to a range of 32.5 kg, and reduced the 95% repeatability coefficient to 18.7 kg. Cow misbehavior during walk-over weighing accounted for many of the larger weight discrepancies. The automated walk-over weighing system showed substantial agreement with the static scales when assessed using Lin's concordance correlation coefficient. This contrasted with limited agreement when assessed using Bland and Altman's method, largely due to poor repeatability. This suggests the automated weighing system is inadequate for detecting small liveweight differences in individual cows based on comparisons of single weights. Misbehaviors and other factors can result in the recording of spurious values on walk-over scales. Excluding outlier weights and comparing means of 7 consecutive daily weights may improve agreement sufficiently to allow meaningful assessment of small short-term changes in automated weights in individuals and groups of cows.

Good communication skills are an important entry-level attribute of graduates of professional degrees. The inclusion of communication training within the curriculum can be problematic, particularly in programs with a high content load, such as veterinary science. This study examined the differences between the perceptions of students and qualified veterinarians with regards to the entry-level communication skills required of new graduates in clinical practice. Surveys were distributed to students in each of the four year levels of the veterinary science degree at the University of Melbourne and to recent graduates and experienced veterinarians registered in Victoria, Australia. Respondents were asked to rank the relative importance of six different skill sets: knowledge base; medical and technical skills; surgical skills; verbal communication and interpersonal skills; written communication skills; and critical thinking and problem solving. They were then asked to rate the importance of specific communication skills for new graduate veterinarians. Veterinarians and students ranked verbal communication and interpersonal skills as the most important skill set for an entry-level veterinarian. Veterinarians considered many new graduates to be deficient in these skills. Students often felt they lacked confidence in this area. This has important implications for veterinary educators in terms of managing the expectations of students and improving the delivery of communication skills courses within the veterinary curriculum.