Condition of surplus dairy calves during marketing: A cross-sectional study.

In North America, surplus dairy calves are sold soon after birth and often marketed through a third party (e.g., live auction, livestock dealer) before entering veal or dairy beef production. Previous work has demonstrated that a percentage of calves have failed transfer of passive immunity (FTPI) and clinical signs of disease on arrival at calf-raising facilities, but little is known regarding calf condition during marketing. The objectives of this cross-sectional study were to (1) estimate the prevalence of FTPI and poor health outcomes in surplus calves on arrival at livestock dealers, and (2) investigate the association between calf-level variables (body weight, sex, source) and health outcomes. Two livestock dealers in Ohio were visited 2 to 3 times per week, with approximately 28 calves enrolled in the study per visit for a total of 1,119 calves. One blood sample per calf was obtained to evaluate FTPI by measuring serum total protein concentrations (using a cutoff <5.1 g/dL). Calves were clinically evaluated for signs of arthritis, broken ribs or tail, dehydration, depression, diarrhea, fever, navel inflammation, and respiratory disease by 2 observers; health outcomes were dichotomized using clinically relevant cut points. Descriptive statistics were used to estimate the prevalence of calves with poor health outcomes. Multivariable logistic regression models were built to investigate the effect of body weight, sex, and source on health outcomes. Nineteen percent (206/1,091) of calves had FTPI.

Measurement-based control of a mechanical oscillator at its thermal decoherence rate.

In real-time quantum feedback protocols, the record of a continuous measurement is used to stabilize a desired quantum state. Recent years have seen successful applications of these protocols in a variety of well-isolated micro-systems, including microwave photons and superconducting qubits. However, stabilizing the quantum state of a tangibly massive object, such as a mechanical oscillator, remains very challenging: the main obstacle is environmental decoherence, which places stringent requirements on the timescale in which the state must be measured. Here we describe a position sensor that is capable of resolving the zero-point motion of a solid-state, 4.3-megahertz nanomechanical oscillator in the timescale of its thermal decoherence, a basic requirement for real-time (Markovian) quantum feedback control tasks, such as ground-state preparation. The sensor is based on evanescent optomechanical coupling to a high-Q microcavity, and achieves an imprecision four orders of magnitude below that at the standard quantum limit for a weak continuous position measurement--a 100-fold improvement over previous reports--while maintaining an imprecision-back-action product that is within a factor of five of the Heisenberg uncertainty limit. As a demonstration of its utility, we use the measurement as an error signal with which to feedback cool the oscillator. Using radiation pressure as an actuator, the oscillator is cold damped with high efficiency: from a cryogenic-bath temperature of 4.4 kelvin to an effective value of 1.1 ± 0.1 millikelvin, corresponding to a mean phonon number of 5.3 ± 0.6 (that is, a ground-state probability of 16 per cent). Our results set a new benchmark for the performance of a linear position sensor, and signal the emergence of mechanical oscillators as practical subjects for measurement-based quantum control.

Whole-Genome Sequencing Reveals the Contribution of Long-Term Carriers in Staphylococcus aureus Outbreak Investigation.

Whole-genome sequencing (WGS) makes it possible to determine the relatedness of bacterial isolates at a high resolution, thereby helping to characterize outbreaks. However, for Staphylococcus aureus, the accumulation of within-host diversity during carriage might limit the interpretation of sequencing data. In this study, we hypothesized the converse, namely, that within-host diversity can in fact be exploited to reveal the involvement of long-term carriers (LTCs) in outbreaks. We analyzed WGS data from 20 historical outbreaks and applied phylogenetic methods to assess genetic relatedness and to estimate the time to most recent common ancestor (TMRCA). The findings were compared with the routine investigation results and epidemiological evidence. Outbreaks with epidemiological evidence for an LTC source had a mean estimated TMRCA (adjusted for outbreak duration) of 243 days (95% highest posterior density interval [HPD], 143 to 343 days) compared with 55 days (95% HPD, 28 to 81 days) for outbreaks lacking epidemiological evidence for an LTC (P = 0.004). A threshold of 156 days predicted LTC involvement with a sensitivity of 0.875 and a specificity of 1. We also found 6/20 outbreaks included isolates with differing antimicrobial susceptibility profiles; however, these had only modestly increased pairwise diversity (mean 17.5 single nucleotide variants [SNVs] [95% confidence interval {CI}, 17.3 to 17.8]) compared with isolates with identical antibiograms (12.7 SNVs [95% CI, 12.5 to 12.8]) (P < 0.0001). Additionally, for 2 outbreaks, WGS identified 1 or more isolates that were genetically distinct despite having the outbreak pulsed-field gel electrophoresis (PFGE) pulsotype. The duration-adjusted TMRCA allowed the involvement of LTCs in outbreaks to be identified and could be used to decide whether screening for long-term carriage (e.g., in health care workers) is warranted. Requiring identical antibiograms to trigger investigation could miss important contributors to outbreaks.

Genome sequencing of an extended series of NDM-producing Klebsiella pneumoniae isolates from neonatal infections in a Nepali hospital characterizes the extent of community- versus hospital-associated transmission in an endemic setting.

NDM-producing Klebsiella pneumoniae strains represent major clinical and infection control challenges, particularly in resource-limited settings with high rates of antimicrobial resistance. Determining whether transmission occurs at a gene, plasmid, or bacterial strain level and within hospital and/or the community has implications for monitoring and controlling spread. Whole-genome sequencing (WGS) is the highest-resolution typing method available for transmission epidemiology. We sequenced carbapenem-resistant K. pneumoniae isolates from 26 individuals involved in several infection case clusters in a Nepali neonatal unit and 68 other clinical Gram-negative isolates from a similar time frame, using Illumina and PacBio technologies. Within-outbreak chromosomal and closed-plasmid structures were generated and used as data set-specific references. Three temporally separated case clusters were caused by a single NDM K. pneumoniae strain with a conserved set of four plasmids, one being a 304,526-bp plasmid carrying bla(NDM-1). The plasmids contained a large number of antimicrobial/heavy metal resistance and plasmid maintenance genes, which may have explained their persistence. No obvious environmental/human reservoir was found. There was no evidence of transmission of outbreak plasmids to other Gram-negative clinical isolates, although bla(NDM) variants were present in other isolates in different genetic contexts. WGS can effectively define complex antimicrobial resistance epidemiology. Wider sampling frames are required to contextualize outbreaks. Infection control may be effective in terminating outbreaks caused by particular strains, even in areas with widespread resistance, although this study could not demonstrate evidence supporting specific interventions. Larger, detailed studies are needed to characterize resistance genes, vectors, and host strains involved in disease, to enable effective intervention.

Prediction of Staphylococcus aureus antimicrobial resistance by whole-genome sequencing.

Whole-genome sequencing (WGS) could potentially provide a single platform for extracting all the information required to predict an organism's phenotype. However, its ability to provide accurate predictions has not yet been demonstrated in large independent studies of specific organisms. In this study, we aimed to develop a genotypic prediction method for antimicrobial susceptibilities. The whole genomes of 501 unrelated Staphylococcus aureus isolates were sequenced, and the assembled genomes were interrogated using BLASTn for a panel of known resistance determinants (chromosomal mutations and genes carried on plasmids). Results were compared with phenotypic susceptibility testing for 12 commonly used antimicrobial agents (penicillin, methicillin, erythromycin, clindamycin, tetracycline, ciprofloxacin, vancomycin, trimethoprim, gentamicin, fusidic acid, rifampin, and mupirocin) performed by the routine clinical laboratory. We investigated discrepancies by repeat susceptibility testing and manual inspection of the sequences and used this information to optimize the resistance determinant panel and BLASTn algorithm. We then tested performance of the optimized tool in an independent validation set of 491 unrelated isolates, with phenotypic results obtained in duplicate by automated broth dilution (BD Phoenix) and disc diffusion. In the validation set, the overall sensitivity and specificity of the genomic prediction method were 0.97 (95% confidence interval [95% CI], 0.95 to 0.98) and 0.99 (95% CI, 0.99 to 1), respectively, compared to standard susceptibility testing methods. The very major error rate was 0.5%, and the major error rate was 0.7%. WGS was as sensitive and specific as routine antimicrobial susceptibility testing methods. WGS is a promising alternative to culture methods for resistance prediction in S. aureus and ultimately other major bacterial pathogens.

Cavity opto-mechanics using an optically levitated nanosphere.

Recently, remarkable advances have been made in coupling a number of high-Q modes of nano-mechanical systems to high-finesse optical cavities, with the goal of reaching regimes in which quantum behavior can be observed and leveraged toward new applications. To reach this regime, the coupling between these systems and their thermal environments must be minimized. Here we propose a novel approach to this problem, in which optically levitating a nano-mechanical system can greatly reduce its thermal contact, while simultaneously eliminating dissipation arising from clamping. Through the long coherence times allowed, this approach potentially opens the door to ground-state cooling and coherent manipulation of a single mesoscopic mechanical system or entanglement generation between spatially separate systems, even in room-temperature environments. As an example, we show that these goals should be achievable when the mechanical mode consists of the center-of-mass motion of a levitated nanosphere.

Enhancement of mechanical Q factors by optical trapping.

The quality factor of a mechanical resonator is an important figure of merit for various sensing applications and for observing quantum behavior. Here, we demonstrate a technique to push the quality factor of a micromechanical resonator beyond conventional material and fabrication limits by using an optical field to stiffen or trap a particular motional mode. Optical forces increase the oscillation frequency by storing most of the mechanical energy in a nearly lossless optical potential, thereby strongly diluting the effect of material dissipation. By placing a 130 nm thick SiO2 pendulum in an optical standing wave, we achieve an increase in the pendulum center-of-mass frequency from 6.2 to 145 kHz. The corresponding quality factor increases 50-fold from its intrinsic value to a final value of Q=5.8(1.1)×10(5), representing more than an order of magnitude improvement over the conventional limits of SiO2 for this geometry. Our technique may enable new opportunities for mechanical sensing and facilitate observations of quantum behavior in this class of mechanical systems.

Risk of Mycoplasma bovis transmission from contaminated sand bedding to naive dairy calves.

The objective of this study was to evaluate the possible transmission of Mycoplasma bovis from positive sand bedding to naïve dairy calves. Twelve preweaned Holstein bull calves were blocked in pairs and randomly assigned as unexposed controls (n=6) bedded with control sand, or exposed calves (n=6) bedded with sand previously positive for M. bovis at a dairy farm. Bedding sand was cultured weekly. Nasal and ear swabs and sera were collected weekly, tracheal swabs were collected monthly, and by the end of the 105-d study, all calves were euthanized (n=10) or died (n=2). Sera were tested for M. bovis-specific antibody. Mycoplasma spp. culture was performed on nasal and ear swabs; culture and a PCR differentiating multiple Mycoplasma spp. were performed on postmortem samples of lung, retropharyngeal lymph node, and trachea from each calf. A complete necropsy also was performed. During 6 wk, mycoplasma concentration in exposed group sand was between 200 and 32,000 cfu/g. All 166 tracheal swabs, nasal and ear swabs, and postmortem tests from all calves were negative for mycoplasma. All 94 sera were negative for M. bovis-specific antibody. No gross pathology suggestive of mycoplasma disease was detected. The probability of mycoplasma detection, if an exposed calf had become infected 4 wk after exposure, ranged between 97 and 99% depending on time of exposure for individual calves. There was no evidence that sand bedding contaminated with M. bovis might serve as a source of transmission to naïve dairy calves.

Lymphokine-activated killer cell phenomenon. III. Evidence that IL-2 is sufficient for direct activation of peripheral blood lymphocytes into lymphokine-activated killer cells.

Purified interleukin 2 (IL-2) was found to be sufficient for direct activation of peripheral blood lymphocytes into lymphokine-activated killer (LAK) cells. The LAK activation factor was directly and consistently associated with IL-2 activity using classic protein purification techniques, adsorption to IL-2-dependent cell lines, and inhibition with anti-Tac antibody. As yet, no other cytokines have been found that perform the same role.

Lymphokine-activated killer cell phenomenon. II. Precursor phenotype is serologically distinct from peripheral T lymphocytes, memory cytotoxic thymus-derived lymphocytes, and natural killer cells.

Culture of human peripheral blood lymphocytes (PBL) in partially purified and lectin-free interleukin 2 results in the generation of cytotoxic effector cells which have the unique property of lysing natural killer (NK)-resistant fresh human tumor cells. We have termed these effector cells "lymphokine- activated killer" cells (LAK). LAK are generated from both normal and cancer patients' PBL and are able to lyse both autologous and allogeneic tumor cells from all histologic tumor types tested. Our previous studies suggested that the LAK phenomenon was distinct from either the cytotoxic thymus-derived lymphocyte (CTL) or NK systems based on a variety of criteria. This study reports that the cell type involved is also distinct, as determined by phenotypic characteristics. The LAK effector cell phenotype was analyzed in parallel with alloimmune CTL, and LAK were found to be similarly susceptible to the monoclonal anti-T cell antibodies OKT-3 or OKT-8 plus complement. In contrast the LAK precursor was not susceptible to the OKT-3 or Leu-1 antibodies plus complement, while the ability to generate alloimmune CTL was totally obliterated when tested using the same PBL responder population; in fact, generation of LAK was found to be augmented five- to sixfold, clearly suggesting that LAK precursor cells are not T lymphocytes as defined by these antibodies. LAK precursors were found to be abundant in NK cell-enriched Percoll gradient fractions, which had been depleted of the 29 degrees C E- rosetting "high affinity" T cells. However, LAK precursors were found to be distinct from the majority of NK cells since lysis of fresh PBL with the monoclonal antibodies OKM-1, Leu-7, or OKT-11 significantly depleted or totally eliminated NK activity, while subsequent activation of the remaining cells generated high levels of LAK and in some cases augmented levels of LAK. LAK precursors were found to be distributed in the thymus, bone marrow, spleen, lymph node, and thoracic duct in addition to the PBL. Therefore, while the cell(s) responsible for activation and expression of LAK activity have some common features with the classic T cell-mediated CTL and NK cell systems, the LAK precursor cells are clearly distinct as determined by phenotype analysis using monoclonal antibodies and complement, and at present must be classified as a "null" cell.

Molecular and spatial epidemiology of human campylobacteriosis: source association and genotype-related risk factors.

The epidemiology of human campylobacteriosis is complex but in recent years understanding of this disease has advanced considerably. Despite being a major public health concern in many countries, the presence of multiple hosts, genotypes and transmission pathways has made it difficult to identify and quantify the determinants of human infection and disease. This has delayed the development of successful intervention programmes for this disease in many countries including New Zealand, a country with a comparatively high, yet until recently poorly understood, rate of notified disease. This study investigated the epidemiology of Campylobacter jejuni at the genotype-level over a 3-year period between 2005 and 2008 using multilocus sequence typing. By combining epidemiological surveillance and population genetics, a dominant, internationally rare strain of C. jejuni (ST474) was identified, and most human cases (65.7%) were found to be caused by only seven different genotypes. Source association of genotypes was used to identify risk factors at the genotype-level through multivariable logistic regression and a spatial model. Poultry-associated cases were more likely to be found in urban areas compared to rural areas. In particular young children in rural areas had a higher risk of infection with ruminant strains than their urban counterparts. These findings provide important information for the implementation of pathway-specific control strategies.

Spatio-temporal epidemiology of Campylobacter jejuni enteritis, in an area of Northwest England, 2000-2002.

A total of 969 isolates of Campylobacter jejuni originating in the Preston, Lancashire postcode district over a 3-year period were characterized using multi-locus sequence typing. Recently developed statistical methods and a genetic model were used to investigate temporal, spatial, spatio-temporal and genetic variation in human C. jejuni infections. The analysis of the data showed statistically significant seasonal variation, spatial clustering, small-scale spatio-temporal clustering and spatio-temporal interaction in the overall pattern of incidence, and spatial segregation in cases classified according to their most likely species-of-origin.

Herd-level prevalence of Johne's disease in Utah and adjacent areas of the intermountain west as detected by a bulk-tank milk surveillance project.

The objectives of this study were to estimate the dairy herd-level prevalence of Johne's disease (JD) in Utah and nearby areas of the intermountain west and to estimate the sensitivity of a single bulk-tank milk test for JD detection. Two milk samples from all bulk tanks on the study farms were collected 1 mo apart. Samples were frozen and shipped to a laboratory for JD testing. An ELISA to measure total IgG antibody specific against Mycobacterium avium ssp. paratuberculosis, the etiological agent that causes JD, and a quantitative real-time PCR to detect M. avium ssp. paratuberculosis DNA were used; both tests were designed for bulk milk. Of the dairy farms in the study area, 170/246 (69%) participated. Positive JD results were found in bulk milk from 67/170 (39%) of dairy farms in Utah and adjacent areas. There were 138 JD-positive bulk-tank results from 241 bulk-tank samples from the 67 positive herds. The sensitivity of the bulk milk testing for detection of JD was 138/241(57%). From the 103 JD-negative farms, 235 bulk-tank samples tested negative for JD. The probability of false-negative results on a single bulk-milk sample was (1 - 0.57) = 0.43. For farms with 1 bulk tank, 2 samples collected 1 mo apart, with both samples testing negative (by both ELISA and quantitative real-time PCR) for JD, the true-negative probability was [1 - (0.43)(2)] = (1 - 0.18) = 82%. For farms with at least 2 bulk tanks, at least 4 samples tested, with all results negative for JD, the true-negative probability was at least 97%. Results support other estimates that prevalence of JD has increased over the last 15 to 20 yr. However, the prevalence detected was 3 times that from a recent report where 13% of dairy herds in the western US were positive. The increase in JD suggests that current control programs, at least as applied, are not effective. Bulk milk testing is a practical way to screen dairy herds for presence of JD. Studies are needed regarding the use of individual cow milk tests for accuracy, practicality, and effectiveness in reducing the prevalence of JD in dairy herds.

Cavity optomechanics with stoichiometric SiN films.

We study high-stress SiN films for reaching the quantum regime with mesoscopic oscillators connected to a room-temperature thermal bath, for which there are stringent requirements on the oscillators' quality factors and frequencies. Our SiN films support mechanical modes with unprecedented products of mechanical quality factor Q(m) and frequency nu(m) reaching Q(m)nu(m) approximately or = 2 x 10(13) Hz. The SiN membranes exhibit a low optical absorption characterized by Im(n) < or approximately equal to 10(-5) at 935 nm, representing a 15 times reduction for SiN membranes. We have developed an apparatus to simultaneously cool the motion of multiple mechanical modes based on a short, high-finesse Fabry-Perot cavity and present initial cooling results along with future possibilities.

Real-time ultrasound elastography of the normal Achilles tendon: reproducibility and pattern description.

AIM: To investigate the feasibility and reproducibility of real-time freehand ultrasound elastography (RTE) of the normal Achilles tendon and to describe its elastographic appearances. MATERIALS AND METHODS: Fifty normal Achilles tendons were prospectively examined using RTE performed by tissue compression using the hand-held transducer. The information was colour-coded (red=soft, green=medium, blue=hard) and superimposed on the B-mode image. Each tendon was examined three times transversely and longitudinally by two radiologists and the ratio between tendon and retro-Achilles fat strain (strain index) was calculated. The reproducibility of the elastograms was assessed qualitatively and quantitatively using the strain index inter and intra observer variation coefficient (intra/inter-CV and intra/inter-CC, respectively). RESULTS: All tendons were clearly visualized on the elastograms. Nineteen tendons (19/50, 38%) appeared homogeneously green/blue (type 1). Thirty-one tendons (31/50, 62%) appeared green with longitudinal red stripes (type 2). The intra- and inter-CC values of the strain index were lower for the transverse plane than for the longitudinal plane (0.43, 0.45, 0.41 and 0.78, 0.66, 0.51, respectively). The intra-CV and inter-CV values were higher for the transverse than for the longitudinal plane measurements (39%, 37%, 30% and 30.50%, 30.10%, 29.60%, respectively). CONCLUSION: RTE of the normal Achilles tendon is a feasible method. The reproducibility of the strain index is good and higher for longitudinal elastograms. Qualitative assessment enables the discrimination of two distinct elastographic patterns. Further studies are required to assess the clinical value of this method.

Evaluation of SexedULTRA 4M™ sex-sorted semen in timed artificial insemination programs for mature beef cows.

An experiment was designed to compare fertility of SexedULTRA 4M™ sex-sorted semen and conventional, non-sex-sorted semen following either fixed-time artificial insemination (FTAI) or split-time artificial insemination (STAI) of mature suckled beef cows. Units of sex-sorted and conventional semen were produced using contemporaneous ejaculates from three commercially available sires. Units of conventional semen were generated with 25.0 × 106 live cells per 0.25 ml straw prior to freezing, and units of sex-sorted semen were generated using the SexedULTRATM Genesis III sorting technology with 4.0 × 106 live cells per 0.25 ml straw prior to freezing. Sex-sorted units were sorted to contain X chromosome-bearing sperm cells at an accuracy level of >90%. Cows (n = 1620) across four herds were treated with the 7-d CO-Synch + CIDR protocol [administration of gonadotropin-releasing hormone (GnRH) and insertion of a progesterone insert (CIDR) on Day -10, followed by administration of prostaglandin F2α (PG) and removal of CIDR inserts on Day -3]. Cows were preassigned based on age, body condition score, and days postpartum to one of the following four treatments: FTAI with SexedULTRA 4M™ sex-sorted semen, FTAI with conventional semen, STAI with SexedULTRA 4M™ sex-sorted semen, or STAI with conventional semen. On Day -3, estrus detection aids (Estrotect®) were applied. For cows in FTAI treatments, AI was performed on Day 0 at 66 h after PG administration and CIDR removal, and 100 µg GnRH was administered concurrent with AI. For cows in STAI treatments, AI was performed on either Day 0 or 1, at 66 or 90 h after PG administration and CIDR removal, based on timing of estrus expression. On Day 1 at 90 h after PG administration and CIDR removal, 100 µg GnRH was administered concurrent with AI to any STAI-treated cows that had failed to express estrus. Pregnancy rates to AI were affected (P = 0.04) by the interaction of bull and semen type. Greater pregnancy rates were obtained with conventional semen versus SexedULTRA 4M™ sex-sorted semen when using semen from Bull A (64% [176/277] versus 36% [100/278]; P < 0.0001) and Bull B (72% [200/277] versus 57% [156/276]; P < 0.01), whereas pregnancy rates to AI did not differ between conventional and SexedULTRA 4M™ sex-sorted semen when using semen from Bull C (58% [149/258] versus 52% [131/254]). Pregnancy rates did not differ significantly between cows inseminated using a STAI versus FTAI approach, regardless of whether insemination was performed with conventional semen (65% [265/409] versus 65% [260/403] or SexedULTRA 4M™ sex-sorted semen (50% [200/403] versus 48% [187/405]). However, due to the additional 24 h for potential estrus expression when performing STAI, total estrous response prior to AI was greater (P < 0.001) among cows receiving STAI (84%; 686/812) compared to FTAI (72%; 585/808), and greater pregnancy rates (P < 0.0001) were obtained among cows that expressed estrus prior to AI. In summary, the relative fertility of SexedULTRA 4M™ sex-sorted semen and conventional semen varied across bulls. Although overall pregnancy rates to timed AI did not differ between STAI and FTAI approaches, use of a STAI approach allowed for greater total estrous response prior to AI. Therefore, to achieve acceptable conception rates per unit and service the maximum number of cows with sex-sorted semen, one viable approach may be to use STAI to maximize total estrous response and restrict use of SexedULTRA 4M™ sex-sorted to only those cows expressing estrus.

Milk production change following clinical mastitis and reproductive performance compared among J5 vaccinated and control dairy cattle.

Naturally occurring cases of bovine clinical mastitis (CM) were studied among J5 vaccinates and controls on 3 commercial dairy farms. Milk production change and reproductive performance following CM were compared between the 2 groups. Among 306 controls and 251 vaccinates, there were 221 new cases of CM affecting 120 cows; 437 lactations never had a case of CM. Environmental pathogens made up 90% (159/176) of etiologic agents isolated. Change in daily milk production following CM was associated with J5 vaccination, days in milk (DIM) at onset of CM, and herd effect as well as each 2-way interaction between the 3 factors. The adjusted daily milk for 21 d following CM was 7.6 kg greater among J5 vaccinates than controls; however, this protective effect of vaccination waned with increasing DIM at onset of CM. A mixed linear model with autoregressive order 1 [AR(1)] correlation structure estimated the daily milk production of any cow (whether or not she had CM) on a given DIM. Cows with CM caused by nonagalactiae streptococci, Staphylococcus aureus, Escherichia coli, or Klebsiella lost significant daily milk production for the entire lactation relative to nonmastitic cows. Another mixed linear model for only coliform CM cases (E. coli, Klebsiella, and Enterobacter) within the first 50 DIM showed milk loss for 21 d following coliform CM to be significantly less for J5 vaccinates than for controls, by 6 to 15 kg per day. Cows were significantly less likely to become pregnant if they had CM caused by E. coli (42% pregnant) or Streptococcus spp. (38% pregnant), whereas 78% (342/437) of cows with no mastitis conceived. Days open (number of days from calving until pregnancy) averaged 131 d for cows with no CM and 162 d for cows that had at least one case of CM. Days until conception, days until last breeding, days open, times bred, and percentage of cows pregnant by 200 DIM were not changed with J5 vaccination. Nonetheless, an important benefit of the use of J5 bacterin appears to be reduction of the loss of daily milk production following CM, whether all cases or only those caused by coliform bacteria were considered.

Epidemiology of gastrointestinal nematode parasitism in a commercial sheep flock and its implications for control programmes.

The epidemiology of nematode infections in a UK commercial crossbred sheep flock was studied from January 2004 to January 2005. The ewes were treated orally with moxidectin when they were turned out of the lambing shed on to nematode-contaminated pasture, and the lambs were treated orally with ivermectin throughout the summer in accordance with the farm's usual practice, with the aim of near-suppressive nematode control. The lactating ewes experienced a significant increase in faecal egg count during the early summer, after the period of persistence of the moxidectin treatment had ended. The ewes' and lambs' egg outputs were dominated by Teladorsagia species, despite the persistence of the effect of moxidectin against this genus. The gimmers (primiparous two-year-old ewes) had a significantly greater faecal egg count at lambing than the three- to four-year-old ewes, but the older ewes had significantly greater post-treatment increases. The population of Trichostrongylus species appeared to follow accepted epidemiological patterns, with no evidence of summer trichostrongylosis. In late summer and autumn the faecal egg output of the ewes was primarily due to large intestinal nematodes.

Elastic strain engineering for ultralow mechanical dissipation.

Extreme stresses can be produced in nanoscale structures; this feature has been used to realize enhanced materials properties, such as the high mobility of silicon in modern transistors. We show how nanoscale stress can be used to realize exceptionally low mechanical dissipation when combined with "soft-clamping"-a form of phononic engineering. Specifically, using a nonuniform phononic crystal pattern, we colocalize the strain and flexural motion of a free-standing silicon nitride nanobeam. Ringdown measurements at room temperature reveal string-like vibrational modes with quality (Q) factors as high as 800 million and Q × frequency exceeding 1015 hertz. These results illustrate a promising route for engineering ultracoherent nanomechanical devices.