Comparison of number of Streptococcus uberis calculated on a volume or weight basis in sand and sawdust bedding.

OBJECTIVE: To determine a method for comparing counts of Streptococcus uberis in sand and sawdust and account for the influence of weight or volume of the bedding material. SAMPLE POPULATION: 2 sources of kiln-dried sawdust and 2 sources of washed sand. PROCEDURES: Sterilized bedding material (100 ml) was weighed and uniformly distributed in an aluminum pan. Each sterilized bedding material was inoculated with a mean of 3.6 X 10(6) (experiment 1) or 2.4 X 10(7) (experiment 2) colony-forming units (CFU) of S uberis/ml of bedding material. Without allowing time for replication of S uberis, inoculated bedding materials were washed with sterile saline (0.9% NaCl) solution. A 200-ml aliquot of wash solution was serially diluted up to 2,500 times with additional saline solution and inoculated on plates containing tryptose agar with 5% sheep blood. After incubation for 48 hours, number of CFU of S uberis was counted. This procedure was replicated 19 and 16 times for each bedding material in experiments 1 and 2, respectively. RESULTS: Evaluation of Bonferroni 95% confidence intervals revealed significant differences for counts of S uberis calculated on a weight basis between sand and sawdust. CONCLUSIONS AND CLINICAL RELEVANCE: Comparison of counts of S uberis determined on a volume basis for sand and sawdust accentuates to a lesser degree the weight difference of the bedding materials and ensures a more appropriate comparison of number of S uberis.

Microbiologic examination of bulk tank milk.

Microbiologic examination of bulk tank milk can be a useful technique in assessment of mastitis and milk quality. Sample collection and handling, laboratory techniques, and interpretation and use of bulk tank microbiology are discussed. Recommendations are made based upon a survey of mastitis laboratories and the author's experience.

Growth of gram-positive mastogenic bacteria in normal, simulated bulk tank, and mastitic milk held at simulated fluctuating temperatures of farm bulk tank.

Growth of Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus bovis, and Streptococcus uberis was studied in normal milk, simulated bulk tank milk, and aseptic mastitic milk held at simulated fluctuating temperatures of farm bulk tank for 48 h. With the exception of S. bovis, growth rates of the other five bacteria were similar in both normal and simulated bulk tank milk. Mastitic milk inhibited growth of all bacteria studied. A 24-h adjustment period occurred before most of the bacteria started growing. The mastitis level in a dairy herd may be monitored by cultures of bulk tank milk samples and by calculations as discussed in this study.

Growth of environmental mastitis pathogens in various bedding materials.

The objective of the study was to determine whether, under controlled conditions, bedding materials vary in their ability to support growth of different environmental pathogens independent of the presence of feces, urine, or other contamination. Five sterilized bedding materials (fine hardwood chips, recycled dried manure, chopped newspaper, softwood sawdust, and chopped straw) and three bacterial species (Escherichia coli, Klebsiella pneumoniae, and Streptococcus uberis) were used for a total of 15 bedding/bacteria combinations, replicated in three trials. Samples were incubated at 37 degrees C, and bacterial counts were determined over 5 d. Rapid growth was seen in straw and recycled manure, some growth occurred in hardwood chips, and a rapid decline in bacterial counts was observed in paper and softwood sawdust. In general, K. pneumoniae and E. coli showed more rapid growth or less rapid decline than did S. uberis. These results demonstrate that clean, damp bedding may support bacterial growth and suggest that high bacterial counts under barn conditions are influenced by factors more complex than type of bedding used.

Influence of Addition of Newly Drawn Milk and Fluctuating Temperatures of Farm Bulk Tanks on Growth of Mastitis-Causing Bacteria.

Effect of addition of newly drawn fresh milk of consecutive milkings on growth of Staphylococcus aureus , Staphylococcus epidermidis , Streptococcus agalactiae , Streptococcus dysgalactiae , and Streptococcus uberis in milk held at fluctuating temperatures of a farm bulk tank for 48 h was studied. There was a statistically insignificant effect of the addition of newly drawn fresh milk of consecutive milkings on the growth rate of S. aureus , S. epidermidis , S. agalactiae and S. uberis but there was a significant (p<0.001) growth enhancing effect on S. dysgalactiae . However, all the bacteria grew significantly (p< 0.001) in milk held at fluctuating temperatures of farm bulk tank for 48 h.

Differential diagnosis of bovine teat lesions.

Teat lesions affect the dairyman by interfering with the milking process or by increasing the likelihood of intramammary infection. Lesions where the skin is broken are frequently infected. The viral, chemical, environmental, and equipment-induced lesions that lead to ulceration, hemorrhage, and scabbing are all associated with increased intramammary infection; however, this association does not necessarily hold true with the less severe conditions. The dry and flakey skin seen with certain teat dips, lime, or sunburn, the common teat-end callous condition, and the mild, temporary congestion or edema sometimes seen after machine milking usually do not lead to increased intramammary infection. When investigating a problem of increased intramammary infection, other factors should be discussed with the dairyman before suggesting that these conditions are the cause of the problem. Before making a diagnosis of machine-induced lesions, the milking equipment should be carefully inspected and tested. Although the equipment can and frequently does cause lesions, it rarely does so if it is properly set or maintained. Maintenance of inflations, pulsators, vacuum regulators, and vacuum pumps will frequently reveal the source of the problem. In most cases, an equipment malfunction must be quite severe to result in teat injury. Many teat-lesion problems are seasonal in occurrence. The problem will frequently subside in the spring only to reoccur in mid fall. In the midwestern United States, most teat-lesion problems occur from November to April. When investigating a teat-lesion complaint, a large proportion of the herd should be examined.(ABSTRACT TRUNCATED AT 250 WORDS)

Uptake on postmilking teat antisepsis.

A review of postmilking teat antisepsis in the control of mastitis is presented. History, development, and evaluation of teat dipping are summarized. General usage procedures are discussed, and limitations and hazards are described. Current recommendations for development of efficacy data on teat dips are outlined. Results of efficacy studies of several classes and formulations of teat dips are compiled.

Subclinical mastitis of beef cows.

Two beef cow herds were investigated to determine the prevalence of subclinical mastitis and to determine whether it contributed to decreased weaning weight of calves nursed by affected cows. Quarter samples obtained about 30 days after calving were evaluated by the California mastitis test and by direct microscopic cell count. In 1 herd, a 92-cow confinement operation, 17 quarters of 12 cows were infected with Staphylococcus aureus, Streptococcus sp other than agalactiae, or Klebsiella sp. Mean 205-day adjusted weights were 203.9 kg and 218.2 kg for calves nursed by infected vs noninfected cows. In the other herd, a 75-cow range-pasture operation, 8 quarters of 8 cows were infected, all with S aureus. Mean 205-day adjusted weights were 162.5 kg and 174.6 kg for calves nursed by infected vs noninfected cows.

Prevalence of chronic teat-end lesions and their relationship to intramammary infection in 22 herds of dairy cattle.

A field study that involved 22 herds of dairy cattle (1,055 lactating cows, 126 nonlactating cows, and 32 heifers) was done to determine the prevalence of teat-end lesions and their relationship to intramammary infection. Teats were grouped into 4 general categories: normal teat ends; smooth, chronic ring lesions; rough, chronic ring lesions; and acute teat-end lesions. Only 15.8% of the teats could be classified as normal; 63.1% had smooth, chronic ring lesions, 13.8% had rough, chronic ring lesions, 0.3% had acute teat-end lesions, and 7% could not be classified. The level of intramammary infection was determined for each teat-end classification. Milk samples were obtained from each mammary gland of all lactating cows. The prevalence of intramammary infection in glands with normal teat ends and in those with chronic ring lesions was not significantly different. Glands with acute teat-end lesions and those in cows in which the teat had been traumatized or leaked milk had higher rates of infection.

Use of a teat sealer for prevention of intramammary infections in lactating cows.

An acrylic latex film that is applied like a teat dip and remains intact as a physical barrier until the next milking was developed and studied with respect to its effect on intramammary infection rates in 4 dairy herds. Rates of new infections in treated quarters were compared with the rates in control quarters on the same cows. A statistically significant reduction in the rates was observed for the following organisms: Staphylococcus aureus, 28%; S epidermidis, 33%; and coliforms, 76%. The percentage reduction for infections caused by Streptococcus agalactiae (18%) and for those caused by streptococcus other than Str agalactiae (7%) were not statistically significant. The film also was shown to be nonirritating.

Phage heterogeneity of coagulase-negative staphylococci isolated in the United States and Sweden from bovine milk.

A Swedish bovine and a Dutch human phage set for coagulase-negative staphylococci were used to phage type coagulase-negative staphylococci isolated from bovine milk from Minnesota dairy herds. A comparison was also made of the deoxyribonuclease activity of coagulase-negative staphylococci isolated from bovine milk in Sweden and Minnesota. Of 133 Minnesota isolates, only one could be typed with the Swedish set and one by the Dutch set, whereas of 218 Swedish strains, 49 could be typed with the Swedish set and 7 by the Dutch set. A larger number of coagulase-negative isolates from Sweden were deoxyribonuclease positive (35%) than were the similar isolates from Minnesota (12%). These findings substantiate the marked heterogeneity of coagulase-negative staphylococci isolated from bovine udders. Results presented point to the usefulness of establishing regional phage sets for epidemiological investigations of coagulase-negative staphylococci in cattle. It is anticipated that at a later stage the regional phage sets will be coordinated internationally.

Screening tests for new teat dips.

Increased use of after-milking teat dips has resulted in the appearance of many new teat dips and a need for methods of evaluation of efficacy. A method was developed for determining the ability of a disinfectant to kill bacteria on the teat ends. Results from several known efficacious products indicated an approximate 95% reduction in bacterial flora. Additional data are presented on some experimental products. This method will provide a measure of effectiveness of a producton teat-skin disinfection. The effect of some changes in the testing procedure on bacterial reduction is demonstrated: 1) Increased times between inoculation and dipping and between dipping and swabbing tended to decrease recoveries on control teats. 2) Saline dips on controls teats provided increased recoveries of test organisms.

A modified membrana nictitians flap technique for the treatment of ulcerative keratitis in cattle.

A modified membrana nictitans flap technique was used successfully in 1,768 of 1,845 (95.8%) cattle with several types of ulcerative keratitis. The flap was easily applied and lasted 7 to 10 days.

The effect of penicillin, dihydrostreptomycin and prednisolone treatment of experimental Candida krusei infections of the mammary glands of dairy cattle.

The growth of Candida krusei in quarters treated intramammary with penicillin, dihydrostreptomycin and prednisolone was compared with growth in untreated quarters. No clinical mastitis occurred in any of the quarters of either group. The number of yeast organisms isolated from the quarter during and after the treatment period appeared similar in both groups. The number of leukocytes in all treated quarters increased during the antibiotic and steroid treatment period but the number of yeast isolated remained the same or decreased as compared to the control quarters.

Prevalence and species distribution of yeast in mammary glands of dairy cows in Minnesota.

A study of the prevalence of yeast-like fungi in the mammary glands of dairy cattle was conducted in Minnesota. Quarter samples from 6,020 cows were cultured for yeast. Growth of organisms was obtained from 3.2% of the quarter milk samples. The rate of yeast infection for Minnesota dairy cattle in this study was 2.0%. The majority of the yeast isolated belonged to one of four species of the Candida genus. Candida krusei, Candida parakrusei, Candida guilliermundi, and Candida tropicalis, comprised 89% of the yeasts isolated. All of these species have been reported to cause clinical mastitis (1, 7, 9, 10, 12, 13, 15, 16). It would appear that yeast-like fungi are of sufficient prevalence in mammary glands that yeast infection would be considered in the differential diagnosis in cases of clinical mastitis.