The effect of 2 different premilking stimulation regimens, with and without a latency period, on teat tissue condition and milking performance in Holstein dairy cows.

The objectives of this study were to assess the effect of 2 different premilking stimulation regimens, with and without a latency period between tactile stimulation and the attachment of the milking unit, on the teat tissue condition and milking performance of dairy cows. In a randomized controlled crossover study, 145 Holstein cows milked 3 times daily were assigned to treatment (TRT) or control (CON) groups. Premilking udder preparation for the TRT group consisted of the application of a latency period resulting in a preparation lag time of 90 s. The only difference in the premilking udder preparation of the CON group was the absence of latency period; the milking unit was attached immediately after completion of the tactile stimulation. The average duration of total tactile stimulation in TRT and CON group was 8 ± 2 and 9 ± 2 s, respectively. The study lasted for 14 d and was split into 2 periods, each consisting of a 2-d adjustment period followed by 5 d of data collection. We assessed machine milking-induced short-term changes to the teat tissue by palpation and visual inspection postmilking. Electronic on-farm milk meters were used to assess milking characteristics (milk yield [kg/milking session], machine-on time [s], 2-min milk yield [kg], and duration of low milk flow rate [s]). Generalized linear mixed models were used to analyze the effect of treatment on the outcome variables. The odds of machine milking-induced short-term changes to the teat tissue were lower for cows that received a 90-s preparation lag time (TRT cows) compared with cows in the CON group (odds ratio [95% confidence interval; 95% CI] = 0.13 [0.08-0.20]). The least squares means (95% CI) values of cows in the TRT and CON groups were 15.4 (14.9-15.9) and 15.3 (14.8-15.8) kg, respectively, for milk yield, and 246 (239-253) and 253 (247-260) s for machine-on time. The 2-min milk yield was higher for the TRT compared with CON group cows at all the parity levels. The 2-min milk yields of animals in lactation 1, 2, and ≥3 were 5.7, 5.7, and 6.5 kg, respectively, in the TRT group and 4.6, 5.0, and 5.9 kg in the CON group. The TRT cows spent less time in low milk flow rate compared with CON cows at all parity levels. The durations of low milk flow rate of cows in lactation 1, 2, and ≥3 in the TRT group were 19, 17 and 13 s, respectively, and those in the CON group were 31, 22, and 15 s. In this study, cows that received a latency period, and thus were subjected to a 90-s preparation lag time had lower odds of exhibiting short-term changes to the teat tissue after machine milking, shorter machine-on time, higher 2-min milk yields, and lower durations of low milk flow rates. We conclude that consideration of latency period leading to a 90-s preparation lag time in the premilking stimulation regimen facilitated cows' milk-ejection reflex. This latency period can alleviate the adverse effects of vacuum-induced forces on teat tissue during machine milking, improve udder health, and promote animal well-being.

A randomized controlled trial assessing the effect of intermittent and abrupt cessation of milking to end lactation on the well-being and intramammary infection risk of dairy cows.

The objectives were to compare the effects of an intermittent milking schedule with a thrice daily milking schedule during the final week of lactation on the well-being, udder health, milk production, and risk of culling of dairy cows. We hypothesized that cows subjected to an intermittent milking schedule would experience less udder engorgement and pain, lower concentrations of fecal glucocorticoid metabolites (11,17-dioxoandrostanes; 11,17-DOA concentration) after dry-off, lower risk of an intramammary infection during the dry period, higher milk production and lower somatic cell count in the subsequent lactation, and lower culling risk compared with herd mates milked 3 times daily and dried off by abrupt cessation. In a randomized controlled field study, Holstein cows (n = 398) with a thrice daily milking schedule were assigned to treatment and control groups. The treatment consisted of an intermittent milking schedule for 7 d before dry-off (gradual cessation of milking, GRAD). Gradual-cessation cows were milked once daily until the day of dry-off, whereas cows in the control group (abrupt cessation of milking, APT) were milked 3 times daily until the day of dry-off. Udder firmness and pain responses of the udder 3 d after dry-off, as well as the percentage change in fecal 11,17-DOA concentration (3 d after dry-off compared with the dry-off day), were used to assess the well-being of the animals. Compared with cows in the GRAD group, the odds [95% confidence interval (CI)] of udder firmness were 1.55 (0.99-2.42) for cows in the APT group, and the odds of a pain response were 1.48 (0.89-2.44) for cows in the APT group. The least squares means (95% CI) of the percentage change in 11,17-DOA concentration were 129.3% (111.1-150.4) for the APT group and 113.6% (97.5-132.4) for the GRAD group. Quarter-level culture results from the periods before dry-off and after calving were compared, to assess the likelihoods of microbiological cure and new infection. Cows in the APT group had lower odds of a new intramammary infection in the dry period [odds ratio, 95% CI: 0.63 (0.37-1.05)], whereas we observed no meaningful differences in the microbiological cure likelihood among groups. The least squares means (95% CI) for somatic cell counts (log10-transformed) were 4.9 (4.8-5.0) in the APT group and 4.9 (4.8-5.0) in the GRAD group. The odds (95% CI) of clinical mastitis in the first 30 d postcalving were 1.32 (0.53-3.30) in the APT group compared with the GRAD group. We observed no meaningful differences in milk production at the first test date postcalving or the culling risk among groups. We conclude that the gradual-cessation protocol tested herein failed to significantly improve animal well-being, udder health, milk production, and survival in the tested study cohort. However, the observed differences in udder firmness, as well as the numerical differences in udder pain and the percentage change in fecal 11,17-DOA concentrations suggest that this line of research may be useful. Future research is needed to develop drying-off strategies that are appropriate for lowering milk production at the end of the lactation and improve animal well-being without compromising udder health.

Comparison of seven antibiotic treatments with no treatment for bacteriological efficacy against bovine mastitis pathogens.

Milk culture results were retrospectively reviewed from 9007 cases of subclinical mastitis affecting cows housed in dairy herds located in New York and northern Pennsylvania. Cases included in this analysis had at least one mastitis pathogen isolated from the initial milk sample, were recultured within 1 mo, had permanent cow identification, and had records of whether mastitis was treated with an antibiotic or no treatment at all. Overall bacteriological cure rate for 21 mastitis pathogens was 68% (6097 of 9007). Antibiotic treated cases had a higher cure rate (75%) than did untreated cases (65%). Antibiotic treatments that significantly differed from the untreated cure rate of 65% were amoxicillin (82%), erythromycin (76%), cloxacillin (73%), and pirlimycin (44%). Cure rates for antibiotic treatments with cephapirin, hetacillin, or penicillin did not differ from the untreated cure rate. Agents for which some antibiotics were associated with increased cure rates compared with no treatment were Streptococcus agalactiae, streptococci other than Strep. agalactiae, and coagulase-negative staphylococci. The antibiotic most commonly associated with higher cure rates was amoxicillin. Most of the 21 mastitis agents showed no difference in bacteriologic cure rates between any of the 7 antibiotic treatments and no treatment.

Clinical comparison of borreliacidal-antibody test with indirect immunofluorescence and enzyme-linked immunosorbent assays for diagnosis of Lyme disease.

OBJECTIVE: To compare the clinical results with the borreliacidal-antibody test (BAT) and two standard screening serologic tests for Lyme disease (LD)-the indirect immunofluorescence assay (IFA) and the enzyme-linked immunosorbent assay (ELISA). DESIGN: The medical records of patients from an endemic LD area, who had been serologically tested during the summer of 1992, were retrospectively categorized by clinical diagnoses without results of serologic tests. Serologic testing, which included control serum samples from patients from a nonendemic LD area, was performed in a blinded fashion, and the results were compared with the clinical categories. MATERIAL AND METHODS: Medical records of 307 patients who had been serologically tested for LD were reviewed. We found untreated, active LD in 43 patients (early-localized LD, 21; early-disseminated LD, 14; and late-disseminated LD, 8) and treated LD in 33. Non-LD cases were categorized into acute or chronic conditions of unknown or known cause. RESULTS: Overall, the BAT had a sensitivity of 11% in active LD and did not correlate with results of other conventional surface antibody assays. The IFA and ELISA were more sensitive (67 to 93%), but false-positive results frequently were noted (20 to 40%) in acute and chronic non-LD inflammatory conditions. The specificity of the BAT, IFA, and ELISA in the control group was 96%, 93%, and 97%, respectively. CONCLUSION: Until the sensitivity, as measured by prospective clinical studies, is improved without loss of specificity, the BAT should not be used clinically for the diagnosis of LD. Suspected cases of LD with atypical clinical manifestations should have positive ELISA and IFA results confirmed with a standardized immunoblot assay.

Detection of borreliacidal antibodies by flow cytometry. An accurate, highly specific serodiagnostic test for Lyme disease.

BACKGROUND: Borreliacidal antibodies can be detected in serum samples from patients with early or late Lyme disease symptoms. When these serum samples are incubated with Borrelia burgdorferi and complement, spirochetes are rapidly killed. Detection of these antibodies can be used as a serodiagnostic test. METHODS: Individual serum samples containing IgM or IgG borreliacidal antibodies were Used to develop a method for detection using flow cytometry. An additional 10 case-defined Lyme disease serum samples and 10 normal serum samples were used to confirm appropriate flow cytometric parameters. To determine specificity, 157 normal serum samples and 104 potential cross-reactive serum samples were tested for borreliacidal activity and antibodies to B burgdorferi using indirect fluorescent antibody or enzyme immunoassay. RESULTS: Flow cytometry can be used to detect borreliacidal activity within 16 to 24 hours after incubation of B burgdorferi organisms. Lyme disease serum, and complement. Significant borreliacidal activity was detected in all Lyme disease serum samples. The percentages of positive normal serum samples were comparable (6% to 10%) using all three assays. In addition, the indirect fluorescent antibody and enzyme immunoassay identified 41 (39%) and 47 (45%) potential cross-reactive serum samples as positive, respectively. In contrast, significant borreliacidal activity was not detected in any potential cross-reactive serum samples. CONCLUSION: Detection of borreliacidal antibody, unlike indirect fluorescent antibody and enzyme immunoassay, is an accurate, highly specific serodiagnostic test for detection of Lyme disease.

Histocompatibility antigens and La Crosse encephalitis.

Major histocompatibility complex antigens (HLA-ABC and -DR loci) on lymphocytes from 79 patients with La Crosse encephalitis were compared with those of 69 control subjects. Nine patients (11%) and none of the control population had HLA-B49 (P < .01, uncorrected for multiple comparisons). Of La Crosse encephalitis patients with acute-phase seizures, only 2 (7%) were positive for HLA-DR5, whereas 16 (37%) of nonseizure patients were positive for that antigen (P < .025). These findings suggest that susceptibility and complications associated with this disease may have an immunogenetic component.

Characterization of the borreliacidal antibody response to Borrelia burgdorferi in humans: a serodiagnostic test.

An in vitro assay was used to characterize the borreliacidal activity of sera from Lyme disease patients. The mean percentage of killing was 23% with sera from patients with a single erythema migrans lesion, 42% from patients with multiple lesions, 58% from patients with Lyme arthritis of short duration, and 83% from patients with Lyme arthritis of long duration. Borreliacidal activity was abrogated when Lyme disease serum was treated with anti-human IgM or IgG1. In addition, human sera from Lyme arthritis patients containing borreliacidal antibody prevented the induction of Lyme arthritis in irradiated hamsters challenged with the Lyme spirochete. Removal of outer surface protein A antibodies from late Lyme disease sera caused reductions in the borreliacidal antibody titer. The results demonstrate an important role for borreliacidal antibody against infection with B. burgdorferi in humans and confirm that detection of borreliacidal antibody in human sera can be a specific serodiagnostic test for Lyme disease.

Performance of 45 laboratories participating in a proficiency testing program for Lyme disease serology.

OBJECTIVE: We show that significant interlaboratory and intralaboratory variations exist in Lyme disease proficiency testing. DESIGN: Six case-defined Lyme serum samples and three serum samples from individuals with no history of Lyme disease were randomized in four shipments and distributed to 45 participating laboratories. RESULTS: Interlaboratory and intralaboratory performances were highly variable. Approximately 4% to 21% of laboratories failed to identify correctly positive serum samples with titers of 512 or more using polyvalent serum or immunoglobulin G conjugates. With lower levels of anti-Borrelia burgdorferi antibody in the serum sample, approximately 55% of participating laboratories did not identify a case-defined serum. There was also a striking inability of many laboratories to reproduce their results on split samples from the same individual. In addition, 2% to 7% of laboratories identified serum samples from individuals with no known exposure to B burgdorferi as positive using polyvalent serum. The false positivity rate increased to 27% with the use of immunoglobulin G conjugate. CONCLUSIONS: Our results indicate that there is an urgent need for standardization of current testing methodologies. Until a national commitment is made, serological testing for Lyme disease will be of questionable value for the diagnosis of the disease.

Lyme disease: clinical features, classification, and epidemiology in the upper midwest.

Lyme disease can be classified using the terminology of syphilis. In this series of 95 cases from the upper midwest, early cases, defined as an illness of less than 2 months, were more likely to have lived in or recently visited a highly endemic area. Unlike late cases, early cases presented entirely in the nonwinter months (p less than .001). Early disease was further subdivided into primary and secondary disease. Ninety percent of primary and 43% of secondary cases had erythema migrans, while no late cases had active erythema migrans (p less than .001). Clinical manifestations of nonspecific inflammation, except for arthralgia, were more common in early than late disease (p less than .01). In secondary cases, monoarticular arthritis was slightly more common than polyarticular arthritis, with the reverse occurring in late disease (p less than .05). Indirect fluorescent antibody testing revealed a ratio of IgM to IgG antibodies to be helpful in distinguishing early from late disease. Antibacterial therapy in early, primary cases caused Jarisch-Herxheimer reaction 7% of the time. Despite longer and more frequent parenteral therapy, late Lyme disease frequently required retreatment, owing to poor clinical response (p less than .05).

Effects of bovine serum albumin on the ability of Barbour-Stoenner-Kelly medium to detect Borrelia burgdorferi.

The ability of decreasing inocula of Borrelia burgdorferi to grow in otherwise identical Barbour-Stoenner-Kelly (BSK) media containing different lots of bovine serum albumin (fraction V) was determined. These media differed significantly in ability to detect B. burgdorferi. Some BSK media required inocula of 2 x 10(5) organisms per ml for detection, while other media could stimulate growth after inoculation with less than 2 organisms per ml. In addition, organisms from the less sensitive BSK media were thinner, longer, and less tightly coiled. The endpoint dilutions of indirect fluorescent-antibody titers, especially immunoglobulin M, exhibited up to 16-fold decreases, and both immunoglobulin G and M titers were more difficult to interpret with diagnostic slides prepared from some longer, thinner B. burgdorferi. These results demonstrate that, when performing laboratory investigations which rely on B. burgdorferi, it is essential that the quality of the BSK medium be determined.