Perspective of dairy producers from California, Idaho, South Dakota, and Washington: Health and business implications of the COVID-19 pandemic during the second wave.

The aim of this study was to document California, Idaho, South Dakota, and Washington dairy producers' perspectives on the health and business implications of COVID-19 during the pandemic second wave. Dairy producers were reached by a 14-question anonymous mail survey during June and July of 2020. We obtained 226 responses (response rate: 9.3% CA, 8.6% ID, 31.4%, and 10.0% WA). Responses were grouped by state (CA: 48.7%, ID: 15.9%, SD: 21.7%, or WA: 13.7%) and dairy size [based on number of cows; small (<100): 14.1%, medium (100-499): 27.7%, medium-large (500-1,999): 33.2%, or large (≥2,000): 25.0%]. Survey responses were summarized, and multiple correspondence analysis was used to map responses and identify data clusters. At the time of the survey, some respondents suspected (3%) or had confirmed (9%) COVID-19 cases on their premises. Respondents were somewhat or very concerned about the health (75%) and business (92%) implications associated with COVID-19. Producers were concerned about the health of their families, employees, and employees' families; having to reduce production; workforce shortage; limited goods availability; and lack of services. Producers perceived that their employees were somewhat or very concerned (74%) with the pandemic. There was COVID-19 safety information or training provided (78%) or intended (4%) in English (22%), Spanish (23%), or both (55%). The focus of training was as follows: how to remain healthy at work (91%) and at home (60%), what to do if a worker gets sick (77%), and sick leave information (54%). Nevertheless, 18% of the respondents answered that training was not going to be provided. The following control measures implemented: providing hand sanitizer or disinfectant wipes (78%), instruction on frequent hand-washing (76%), social distancing (59%), prevention of employee gatherings (54%), providing and requiring the use of face masks (49%), and limiting on-farm visitors (44%). Multiple correspondence analysis showed that concern with health risk and business impact of the COVID-19 pandemic, as well as mitigation and response strategies implemented, varied based on respondent's dairy size and state. The greatest concerns were reported by producers from California and large and medium-large dairies, whereas the fewest concerns were reported by producers from small dairies. Results from this survey highlighted the health and business concerns of dairy producers from California, Idaho, South Dakota, and Washington during the COVID-19 pandemic and the mitigation efforts adopted. In conclusion, mitigation measures were adopted by most dairy producers but in various degrees. Dairy industry service providers and educators were secondary educational resources during the pandemic; thus, future efforts toward centralized access to dairy specific bilingual educational materials are suggested.

Low colostrum yield in Jersey cattle and potential risk factors.

Consumption of an adequate volume of high-quality colostrum is vital to a dairy calf's ability to survive and become a productive herd member. However, some dairy herds have reported a deficiency of colostrum production, which ranges from a low volume to no colostrum produced, by cows during fall and winter. Little information regarding this phenomenon exists. The purpose of this study was to characterize the syndrome and identify potential risk factors for low colostrum yield. A 2,500-cow Jersey dairy farm was enrolled in a prospective cohort study in May 2016, to evaluate possible effects of photoperiod, temperature, and cow factors on colostrum production. Dairy personnel were trained to collect, weigh, and evaluate colostrum quality. Information on parity, previous lactation length, previous 305-d mature-equivalent milk production, and dry period length were collected through the farm's dairy management software. Weather and photoperiod data were also collected. Over the year of enrollment, 2,988 eligible cows calved and had colostrum weights recorded and 38% were primiparous (n = 1,143), 25% were in their second lactation (n = 752), and 37% were in their third or greater lactation (n = 1,093). The overall average colostrum yield was 6.6 kg/cow in June 2016, 2.5 kg/cow in December 2016, and 4.8 kg/cow in May 2017. Multiparous cows had a larger decline in colostrum production between June and December (6.6 to 1.3 kg/cow) compared with primiparous animals (6.5 to 4.2 kg/cow). Overall, average colostrum production decreased by 0.17 kg/cow per week during this time, 0.22 kg for multiparous cows and 0.08 kg for primiparous cows. A logistic regression model was constructed for all cows to evaluate effects of cow factors on low colostrum production (<2.7 kg at first milking). Dry period length, calf sex, singleton or twin, age at freshening, month of calving and previous lactation length were significantly associated with the probability of low colostrum yield (<2.7 kg at first milking). A cross-correlation function analysis between the time series for colostrum yield and photoperiod revealed a high correlation at the time of calving and 1 mo prior, particularly for multiparous cows. A pedigree analysis showed that extreme colostrum yield (low vs. high) followed some sire lines. Low colostrum production in this herd could have an economic effect on the dairy and calf health and appears to have a strong seasonal and, potentially, a genetic component.

Collective Deceleration of Laser-Driven Electron Bunches.

Few-fs electron bunches from laser wakefield acceleration (LWFA) can efficiently drive plasma wakefields (PWFs), as shown by their propagation through underdense plasma in two experiments. A strong and density-insensitive deceleration of the bunches has been observed in 2 mm of 10^{18} cm^{-3} density plasma with 5.1 GV/m average gradient, which is attributed to a self-driven PWF. This observation implies that the physics of PWFs, usually relying on large-scale rf accelerators as drivers, can be studied by tabletop LWFA electron sources.

Tunable all-optical quasimonochromatic thomson x-ray source in the nonlinear regime.

We present an all-laser-driven, energy-tunable, and quasimonochromatic x-ray source based on Thomson scattering from laser-wakefield-accelerated electrons. One part of the laser beam was used to drive a few-fs bunch of quasimonoenergetic electrons, while the remainder was backscattered off the bunch at weakly relativistic intensity. When the electron energy was tuned from 17-50 MeV, narrow x-ray spectra peaking at 5-42 keV were recorded with high resolution, revealing nonlinear features. We present a large set of measurements showing the stability and practicality of our source.

Association of abnormal hind-limb postures and back arch with gait abnormality in dairy cattle.

Detection of lameness in individual cows is important for the prompt treatment of this painful and production-limiting disease. Current methods for lameness detection involve watching cows walk for several strides. If clinical signs predictive of lameness could be observed more conveniently, as cows are undergoing regularly scheduled examinations while standing, detection levels could increase. The objective of this study was to assess the association between postures observed while cows are standing in stanchions and clinical lameness evaluated by locomotion scoring, and to evaluate the observation of these postures as a test for lameness. The study included 1,243 cows from 4 farms. Cows were observed while standing in stanchions for regularly scheduled management procedures and the presence of arched back and cow-hocked, wide-stance, and favored-limb postures were recorded. The same cows were locomotion-scored as they exited the milking parlor. The proportion of cows observed with arched back and cow-hocked and favored-limb postures increased with increasing severity of lameness (higher locomotion score) but did not increase for the wide-stance posture. For the presence of these postures as a test for lameness (locomotion score ≥3), sensitivity and specificity were 0.63 and 0.64 for back arch, 0.54 and 0.57 for cow hocks, and 0.05 and 0.98 for favored limb. Back-arched, cow-hocked, and favored limb postures were associated with lameness but were not highly sensitive or specific as diagnostic tests. However, observation of back arch may be useful to identify cows needing further examination.

Shock-front injector for high-quality laser-plasma acceleration.

We report the generation of stable and tunable electron bunches with very low absolute energy spread (ΔE ≈ 5 MeV) accelerated in laser wakefields via injection and trapping at a sharp downward density jump produced by a shock front in a supersonic gas flow. The peak of the highly stable and reproducible electron energy spectrum was tuned over more than 1 order of magnitude, containing a charge of 1-100 pC and a charge per energy interval of more than 10 pC/MeV. Laser-plasma electron acceleration with Ti:sapphire lasers using this novel injection mechanism provides high-quality electron bunches tailored for applications.

Comparison of modeled sampling strategies for estimation of dairy herd lameness prevalence and cow-level variables associated with lameness.

Monitoring herd lameness prevalence has utility for dairy producers and veterinarians in their efforts to reduce lameness, for animal welfare assessment programs, and for researchers. Locomotion scoring is a method used to quantify lameness and calculate prevalence. Because of the time necessary to locomotion score each cow in large dairy herds, a sampling strategy to determine herd lameness prevalence that allows scoring of fewer cows would be useful. Such a sampling strategy must be validated for accuracy compared with the lameness prevalence when all cows in a herd are locomotion scored. The purpose of this study was to assess 3 previously suggested methods of estimating lameness prevalence by strategic sampling of dairy herds. Sampling strategies tested included (1) sampling a calculated number of cows in the middle third of the milking parlor exit order for each pen, (2) sampling a calculated number of cows weighted across pens and distributed evenly within each pen, and (3) sampling all cows in the high production, low production, and hospital pens. Lactating cows on 5 dairy farms in Washington and Oregon (n=4,422) were locomotion scored using a 5-point scale to determine herd-level lameness prevalence (percentage with locomotion score ≥3). Milking parlor exit order, order in headlocks at the feed bunk within each pen, and breed were recorded for each cow. The number of days in lactation, milk production, and parity were collected from farm computer records. Pen grouping strategy for each farm was obtained by interview with farm management. Sampling strategies were modeled using the locomotion score data set for each herd. Estimates of lameness prevalence obtained from the milking parlor exit order sample and the sample distributed across pens were within 5 percentage points of the whole herd prevalence. The third strategy estimated the lameness prevalence within 5 percentage points on 4 farms, but overestimated prevalence on 1 farm. Pen-level prevalence obtained by locomotion score of all cows in the pen was variable and not reliably predictive of herd-level prevalence. Cows of Holstein breed, parity >1, and exiting the milking parlor in the last 20% of the pen had greater odds of lameness compared with other breeds, parities, and milking parlor exit order groups in a multivariate analysis. This study indicates that the sampling strategies using the middle of milking parlor exit order and a calculated sample distributed across the herd may be used to obtain an estimate of herd lameness prevalence.

Pharmacological inhibition of beta-catenin in hepatoblastoma cells.

PURPOSE: The proto-oncogene beta-catenin is linked to an abnormal activation of the Wnt/beta-catenin-pathway and shows mutations in 50-90 % of hepatoblastoma (HB). Corresponding, the recently published murine orthotopic HB model differs from the former subcutaneous model by nuclear beta-catenin distribution. As the nuclear localization of beta-catenin is considered to reflect a more aggressive tumor growth, the influence of beta-catenin inhibition on cell viability and drug-efficiency in HB cells was analyzed. METHODS: Beta-catenin distribution in HB cells was analyzed by immunofluorescence. The influence of beta-catenin inhibitors Celecoxib, Etodolac, ICG001, and MET kinase inhibitor (SU11274) alone and in combination with cisplatin (CDDP) on HB cell lines (HuH6, HepT1) was evaluated by cell viability assays and BrdU incorporation. RESULTS: Celecoxib and ICG001 reduced dose-dependently HB cell viability and decreased nuclear beta-catenin in cultivated HB cells. Etodolac was without influence at concentrations up to 100 µM. Combinations of Celecoxib or ICG001 with MET kinase inhibitor or CDDP resulted in additive reduction of cell viability. CONCLUSION: Pharmaceutical beta-catenin inhibitors can modulate the nuclear localization of beta-catenin and reduce cell viability of HB cells in vitro. These promising effects might optimize the outcome of high-risk HB. The orthotopic HB model is a suitable basis for further in vivo studies.

Perspectives of dairy employees at the beginning of the COVID-19 pandemic: A survey of health risks and educational needs.

Our objective was to understand dairy employees' perceptions and educational needs at the onset of the COVID-19 pandemic. A bilingual (English and Spanish), anonymous survey targeted at dairy employees was circulated nationwide via university and allied industry media outlets. Responses (n = 63) from 11 states were received (May-Sep. 2020). Respondents worked in herds ranging from 50 to 40,000 animals in size. Dairy managers (33%) responded mostly to the English survey (52%), whereas entry-level workers (67%) chose the Spanish format (76%). Survey results highlighted different perspectives, educational needs, and preferred sources of information between English- and Spanish-speaking dairy workers. Overall, 83% of the respondents were somewhat concerned or very concerned about the COVID-19 pandemic. Respondents (51%) indicated that their main concern was "to bring the virus from work to home and make my family sick." Most dairy employees (83%) perceived that their employers were somewhat or very concerned about the pandemic. Respondents (65%) indicated that COVID-19 informative training was provided at the workplace, but training was more frequently undertaken among dairy managers (86%) than entry-level workers (53%). Most trainings (72%) were limited to posters on walls. The preferred means of information delivery was through in-person meetings at work (35%), with YouTube (29%) and on-demand videos (27%) as second and third options. The main source of information regarding the pandemic was social media (52%). Frequent handwashing (81%), limiting on-farm visits (70%), limiting agglomeration in break rooms (65%), hand sanitizer use (60%), and social distancing (60%) were the most common safety measures implemented at the workplace among the options given to respondents. Few respondents (38%) indicated that face-covering was required at work. Successful emergency plans on dairies should consider the outreach needs and preferences of dairy workers.

Short communication: Effects of dairy calf hutch elevation on heat reduction, carbon dioxide concentration, air circulation, and respiratory rates.

Heat stress affects dairy calf welfare and can result in morbidity, mortality, and lower weight gain. The purpose of this project was to evaluate the effects of elevating the back of plastic calf hutches on measures of ventilation and heat stress. A total of 15 calves housed in individual hutches were enrolled, with each calf hutch serving as its own control. Heat, humidity, carbon dioxide, and wind speed were measured inside each hutch and the observations were compared with external measurements over two 24-h periods; 1 period without and 1 with hutch elevation. Respiratory rates were measured in the morning and afternoon as an indicator of the degree of heat stress experienced by calves with and without elevation of the hutch. When the hutch was elevated, internal hutch temperatures were cooler than external temperatures, hutch carbon dioxide levels were lower and respiratory rates were lower, particularly comparing the afternoon observation periods.

Retrospective evaluation of health event data recording on 50 dairies using Dairy Comp 305.

The purpose of this study was to characterize health data recording in herds using Dairy Comp 305 (Valley Agricultural Software, Tulare, CA), focused on the most common diseases of dairy cattle: mastitis, uterine infection (metritis), and diseases causing lameness. Herds using Dairy Comp 305 were chosen for the study because it was the most commonly used program in the United States (35% of operations using computer records/60% of cows on operations using computer records), the authors were familiar with the program, and there was convenient access to herds using the program. Specific objectives were to (1) determine the percentage of herds recording mastitis, metritis, and diseases causing lameness and the number of user-defined events used to record those diseases, (2) identify the information recorded in the remarks about the event used for each disease, and (3) evaluate the consistency of health event remarks recorded. A convenience sample of 50 Dairy Comp 305 compressed cow files was obtained directly from dairies that the authors had contact with or files obtained from industry consultants. The 50 herds included in the study were from 9 different states: California (n=3), Colorado (n=2), Iowa (n=2), Idaho (n=8), Minnesota (n=2), New Mexico (n=9), Oregon (n=2), Texas (n=2), Utah (n=1), and Washington (n=19). The average number of milking cows of the herds was 3,053 (median=2,217), ranging from 310 to 12,490 cows. The majority of dairies in this study were recording health events associated with mastitis, metritis, and diseases causing lameness. However, as reported previously, most health records observed in the current study lacked the accuracy and consistency needed to be useful for evaluating and informing herd-level health management decisions. This situation likely reflects the intended use of those records by farm personnel and the user-defined nature of health records in the absence of accepted industry standards or recommendations for health data-recording practices.

Intramammary infections and teat canal colonization with coagulase-negative staphylococci after postmilking teat disinfection: species-specific responses.

Coagulase-negative staphylococci (CNS) are the most common pathogens associated with intramammary infections (IMI) in dairy cows. We hypothesized that postmilking teat disinfection would reduce microbial colonization of the teat canal and thus reduce the prevalence of IMI caused by certain CNS species. The efficacy of iodine postmilking teat dip was tested against CNS colonization of the teat canal, and incidence of IMI was measured. Using an udder-half model, 43 Holstein cows at the Washington State University Dairy were enrolled in the trial; postmilking teat dip was applied to one udder-half, treatment (TX), and the remaining half was an undipped control (CX). Teat canal swabbing and mammary quarter milk samples were taken in duplicate once a week for 16 wk for microbial culture. Isolates from agar cultures were presumptively identified as CNS and then speciated using PCR-RFLP and agarose gel electrophoresis. Colonization of the teat canal and IMI by CNS were assessed. Thirty CNS IMI were diagnosed and the number of new IMI in CX quarters (21) was significantly greater than that in TX mammary quarters (9). The majority of CNS IMI were caused by Staphylococcus chromogenes (30%) and Staphylococcus xylosus (40%), and the latter were appreciably reduced by teat dip. Except for S. xylosus, an association was observed between teat canal colonization and IMI by all CNS species in this study, in which the majority of IMI were preceded by teat canal colonization. The total number of CNS IMI was greater for CX group cows compared with TX group cows. However, the effect of disinfection on IMI did not appear to be the same for all CNS species.

Factors associated with the rectal temperature of Holstein dairy cows during the first 10 days in milk.

Daily evaluation of rectal temperature (RT) during the first 10 d in milk (DIM) is used to facilitate the early identification of postpartum complications, particularly metritis in dairy cows. The factors associated with RT of postpartum dairy cows have not been clearly established and the RT threshold used to define fever has been variable. The objectives were to identify factors associated with the RT of postpartum dairy cows and provide descriptive statistics of the RT during the first 10 DIM to clarify the normal range of RT for cows. Daily RT was evaluated from 1 to 10 DIM for all cows calving during 2 consecutive summers on a single 1,500-cow Holstein dairy. Cows were placed into metabolic/digestive (METB), infectious (INF), and no recorded disease (NONE) groups based on disease diagnoses during the first 10 DIM. Cows were grouped based on calving difficulty and parity. Multiple linear regression models with repeated measures were used to evaluate the factors associated with RT. Three hundred and ninety-two cows were evaluated, of which 45% were primiparous and 32% required assistance at calving. No difference was observed in calving assistance by parity. First disease diagnoses peaked in the INF and METB groups at 3 and 1 DIM, respectively. The RT of primiparous cows was 0.1 to 0.2°C higher than that of multiparous cows from 1 to 8 DIM, accounting for calving difficulty, twin births, month of calving, and disease group in the model. The INF group cows had a higher RT than did NONE group cows (38.9±0.04 to 39.2±0.73 vs. 38.7±0.03°C, respectively) on each of the first 10 DIM, which was approximately 0.6°C higher from 3 to 5 DIM. The RT of cows with metritis was at least 0.1°C higher (38.8±0.05°C) than that of NONE group cows beginning 4 d before diagnosis. The mean RT of primiparous, defined healthy (NONE group) cows was 38.8±0.02°C, with an upper normal limit (mean+2 SD) of 39.6°C. The mean RT of multiparous cows in the NONE group during the first 10 DIM was 38.7±0.01°C, with an upper normal limit of 39.5°C. The RT of dairy cattle during the first 10 DIM was associated with parity, month of calving, and an infectious disease diagnosis, particularly the diagnosis of metritis. The normal RT of dairy cattle in the immediate postpartum period, during the warm summer months, is potentially higher than that generally reported.

Factors associated with concentrations of select cytokine and acute phase proteins in dairy cows with naturally occurring clinical mastitis.

The objective of the current observational study was to determine the potential associations between cow factors, clinical mastitis (CM) etiology, and concentrations of select acute phase proteins and cytokines in milk from affected quarters of cows with CM. Cows with CM (n=197) were grouped based on systemic disease severity, milk culture result, parity, days in milk (DIM), previous CM occurrence, and season of the year when CM occurred. Concentrations of lipopolysaccharide-binding protein (LBP), haptoglobin (Hp), BSA, IFN-gamma, tumor necrosis factor-alpha (TNF-alpha), IL-1beta, IL-8, IL-10, IL-12, transforming growth factor (TGF)-alpha, and TGF-beta and activity of lactate dehydrogenase (LDH) were evaluated. Differences in the least squares means log(10) transformed concentrations of these proteins were compared using multiple linear regression mixed models. The milk concentrations of LBP, Hp, IL-1beta, IL-10, and IL-12, and activity of LDH in milk were higher in cows with moderate to severe versus mild systemic disease. The concentrations of Hp, BSA, IL-1beta, and IL-10 in milk were higher in cows with a gram-negative versus gram-positive milk culture result. Season of the year when CM occurred was associated with the concentration of all proteins evaluated except for IL-1beta and IL-12. Concentrations were higher in the winter versus summer except for Hp and TGF-beta, for which the opposite was true. Concentrations of LBP, IL-10, and IL-12, and LDH activity in milk were associated with DIM group. Except for LBP, these proteins were lower in cows with CM during the first 60 DIM versus those in mid or later lactation. Interferon-gamma, TNF-alpha, and IL-8 were undetectable in 67, 31, and 20% of samples, respectively. Detection of IFN-gamma and IL-8 was associated with season, and detection of TNF-alpha and IL-8 was associated with systemic disease severity. The current study provides the most comprehensive report of milk concentrations of innate immune response proteins in cows with naturally occurring CM and identifies factors that potentially influence those concentrations. Further investigation into the seasonal variation of cytokine production and its potential effect on the outcome of CM is warranted. Furthermore, the results of this study provide useful data for planning future studies examining the role of the innate immune response in CM.

Water-Window X-Ray Pulses from a Laser-Plasma Driven Undulator.

Femtosecond (fs) x-ray pulses are a key tool to study the structure and dynamics of matter on its natural length and time scale. To complement radio-frequency accelerator-based large-scale facilities, novel laser-based mechanisms hold promise for compact laboratory-scale x-ray sources. Laser-plasma driven undulator radiation in particular offers high peak-brightness, optically synchronized few-fs pulses reaching into the few-nanometer (nm) regime. To date, however, few experiments have successfully demonstrated plasma-driven undulator radiation. Those that have, typically operated at single and comparably long wavelengths. Here we demonstrate plasma-driven undulator radiation with octave-spanning tuneability at discrete wavelengths reaching from 13 nm to 4 nm. Studying spontaneous undulator radiation is an important step towards a plasma-driven free-electron laser. Our specific setup creates a photon pulse, which closely resembles the plasma electron bunch length and charge profile and thus might enable novel methods to characterize the longitudinal electron phase space.

Laser-driven x-ray and proton micro-source and application to simultaneous single-shot bi-modal radiographic imaging.

Radiographic imaging with x-rays and protons is an omnipresent tool in basic research and applications in industry, material science and medical diagnostics. The information contained in both modalities can often be valuable in principle, but difficult to access simultaneously. Laser-driven solid-density plasma-sources deliver both kinds of radiation, but mostly single modalities have been explored for applications. Their potential for bi-modal radiographic imaging has never been fully realized, due to problems in generating appropriate sources and separating image modalities. Here, we report on the generation of proton and x-ray micro-sources in laser-plasma interactions of the focused Texas Petawatt laser with solid-density, micrometer-sized tungsten needles. We apply them for bi-modal radiographic imaging of biological and technological objects in a single laser shot. Thereby, advantages of laser-driven sources could be enriched beyond their small footprint by embracing their additional unique properties, including the spectral bandwidth, small source size and multi-mode emission.

Herd management practices and their association with bulk tank somatic cell count on United States dairy operations.

The objective of this study was to evaluate associations between bulk tank somatic cell count (BTSCC) and herd management practices using data collected in the National Animal Health Monitoring System Dairy 2002 study. Twenty-six percent and 17.8% of 1,013 operations reported a BTSCC < 200,000 cells/mL and > 400,000 cells/mL, respectively. Univariate analysis identified associations between management variables and BTSCC. The use of mattresses, sand, and newspaper as bedding were all associated with a lower BTSCC. Primary lactating cow housing facility, outside maternity housing area, flooring type cows walk or stand on, and use of automatic take-offs were also associated with BTSCC. Multivariate associations between management variables and BTSCC were determined by backward elimination ordinal logistic regression. The odds of an operation from the West, Midwest, and Northeast having a high BTSCC were lower than those from the Southeast. The odds of a higher BTSCC were 2 times greater for operations with a rolling herd average milk production < 9,090 kg/cow per year compared with those with > or = 9,090 kg/cow per year. Operations using composted manure were 2.9 times more likely to have a higher BTSCC than those not using composted manure. Finally, operations that reported not using a coliform mastitis vaccine were 1.7 times more likely to have a higher BTSCC than those using one. Future studies of the association between management practices and BTSCC should include an evaluation of the quality of management practice application and herd prevalence of contagious mastitis pathogens. Significant variables identified in this study dealt with housing, use of composted manure for bedding, and coliform mastitis vaccine use, suggesting the effect of environmental mastitis pathogens may be more influential on BTSCC than previously thought.

Escherichia coli isolates' serotypes, genotypes, and virulence genes and clinical coliform mastitis severity.

Dairy cattle with clinical mastitis caused by Escherichia coli exhibit a wide range of disease severity, from mild, with only local inflammatory changes of the mammary gland, to severe, with significant systemic derangement. The present study was designed to examine the relationship between serotype and virulence genes of E. coli mastitis isolates, different levels of systemic disease severity, and farm from which the E. coli strain was obtained. One hundred twenty-three E. coli milk isolates were obtained from cows with clinical mastitis of varying systemic disease severity from 6 different farms. No predominant serotype was identified by farm or by systemic disease severity; however, the most frequent serotype, O158:NM (n = 3), was isolated from cows in the moderate severity group. Virulence genes evaluated were identified infrequently and were not associated with systemic disease severity. Evaluation of genetic similarity showed no clustering assigned by farm or mastitis severity based on systemic disease signs. We concluded that a high degree of genotypic variability is characteristic of E. coli strains causing clinical mastitis within and between different farms and systemic severity groups, and that specific cow factors probably play a more important role in determining systemic disease severity.

Niacin revisited. A randomized, controlled trial of wax-matrix sustained-release niacin in hypercholesterolemia.

Two hundred one male and female subjects, aged 20 to 70 years, with elevated low-density lipoprotein cholesterol values (in the 75th to 95th percentiles), participated in a randomized, controlled, double-blind study using a new form of niacin (Enduracin), which employs a wax-matrix vehicle for sustained release. Four niacin treatment groups (daily doses of 2000, 1500, 1250, and 1000 mg) were compared with placebo- and diet-treated controls to determine side-effect profile and optimal range of efficacy. The groups given 2000 and 1500 mg demonstrated significant reductions in values of low-density lipoprotein cholesterol (-26% and -19.3%, respectively), total cholesterol (-18.4% and -13.3%), and total cholesterol-high-density lipoprotein cholesterol ratio (-20.4% and -19.4%) when compared with diet- and placebo-treated controls. Smaller improvements were seen in high-density lipoprotein cholesterol and triglyceride levels. Blood chemistry monitoring indicated that reduction in low-density lipoprotein cholesterol level strongly correlated with an increase in baseline levels of some enzymes for niacin-treated subjects. The improved side-effect profile of the wax-matrix form of niacin was particularly notable. The dropout rate due to side effects was only 3.4% and was coupled with good medication compliance.

Short communication: Efficacy of parenteral ceftiofur for treatment of systemically mild clinical mastitis in dairy cattle.

The objective of this study was to evaluate the effect of intramuscular (i.m.) ceftiofur (2.2 mg/kg) on important outcomes of systemically mild clinical mastitis episodes in lactating dairy cattle. Cows with clinical mastitis were randomly assigned to a treatment group: pirlimycin intramammary (i.m.m.) (n = 35), pirlimycin i.m.m. and ceftiofur i.m.m. (n = 36), cephapirin i.m.m. (n = 40), cephapirin i.m. and ceftiofur i.m. (n = 33). Sixty-nine, 22, and 9% of initial cultures were gram-negative, gram-positive, and mixed, respectively. Logistic regression analysis showed no significant associations between treatment groups and loss of quarter, recurrence, or culling. Mixed infections, positive milk culture at 7 d after leaving hospital pen, decreased rumen motility, and absence of udder firmness were associated with increased odds of mastitis recurrence. The results suggest that i.m. ceftiofur treatment has no beneficial effects on the outcome of systemically mild clinical mastitis.