Bovine respiratory disease (BRD) is the major cause of clinical disease and death in feedlot populations worldwide. A longitudinal study was conducted to assess associations between risk factors ...related to on-farm management prior to transport to the feedlot and risk of BRD in a population of feedlot beef cattle sourced from throughout the cattle producing regions of Australia. Exposure variables were derived from questionnaire data provided by farmers supplying cattle (N=10,721) that were a subset of the population included in a nationwide prospective study investigating numerous putative risk factors for BRD. Causal diagrams were used to inform model building to allow estimation of effects of interest. Multilevel mixed effects logistic regression models were fitted within the Bayesian framework. Animals that were yard weaned were at reduced risk (OR: 0.7, 95% credible interval: 0.5–1.0) of BRD at the feedlot compared to animals immediately returned to pasture after weaning. Animals that had previously been fed grain (OR: 0.6, 95% credible interval: 0.3–1.1) were probably at reduced risk of BRD at the feedlot compared to animals not previously fed grain. Animals that received prior vaccinations against Bovine viral diarrhoea virus 1 (OR: 0.8, 95% credible interval: 0.5–1.1) or Mannheimia haemolytica (OR: 0.8, 95% credible interval: 0.6–1.0) were also probably at reduced risk compared to non-vaccinated animals. The results of this study confirm that on-farm management before feedlot entry can alter risk of BRD after beef cattle enter feedlots.
ABSTRACT
The Parkes Pulsar Timing Array (PPTA) project monitors two dozen millisecond pulsars (MSPs) in order to undertake a variety of fundamental physics experiments using the Parkes 64-m radio ...telescope. Since 2017 June, we have been undertaking commensal searches for fast radio bursts (FRBs) during the MSP observations. Here, we report the discovery of four FRBs (171209, 180309, 180311, and 180714). The detected events include an FRB with the highest signal-to-noise ratio ever detected at the Parkes Observatory, which exhibits unusual spectral properties. All four FRBs are highly polarized. We discuss the future of commensal searches for FRBs at Parkes.
We present results from a search for 21 cm associated H i absorption in a sample of 29 radio sources selected from the Australia Telescope 20 GHz survey. Observations were conducted using the ...Australia Telescope Compact Array Broadband Backend, with which we can simultaneously look for 21 cm absorption in a redshift range of 0.04 ≲z≲ 0.08, with a velocity resolution of 7 km s−1. In preparation for future large-scale H i absorption surveys we test a spectral-line finding method based on Bayesian inference. We use this to assign significance to our detections and to determine the best-fitting number of spectral-line components. We find that the automated spectral-line search is limited by residuals in the continuum, both from the band-pass calibration and spectral-ripple subtraction, at spectral-line widths of Δv
FWHM≳ 103 km s−1. Using this technique we detect two new absorbers and a third, previously known, yielding a 10 per cent detection rate. Of the detections, the spectral-line profiles are consistent with the theory that we are seeing different orientations of the absorbing gas, in both the host galaxy and circumnuclear disc, with respect to our line of sight to the source. In order to spatially resolve the spectral-line components in the two new detections, and so verify this conclusion, we require further high-resolution 21 cm observations (∼0.01 arcsec) using very long baseline interferometry.
•Seroepidemiology of BVDV-1, BoHV-1, BRSV and BPIV-3 and risk of BRD was investigated.•For each virus, being seronegative at entry increased risk of BRD in feedlot cattle.•Animals seronegative for ...more than one virus were at progressively increased risk.•For each virus seroincrease resulted in increased risk of BRD in feedlot cattle.•Seroincrease for more than one virus further increased risk of BRD.
Bovine respiratory disease (BRD) is the most important cause of clinical disease and death in feedlot cattle. Respiratory viral infections are key components in predisposing cattle to the development of this disease. To quantify the contribution of four viruses commonly associated with BRD, a case-control study was conducted nested within the National Bovine Respiratory Disease Initiative project population in Australian feedlot cattle. Effects of exposure to Bovine viral diarrhoea virus 1 (BVDV-1), Bovine herpesvirus 1 (BoHV-1), Bovine respiratory syncytial virus (BRSV) and Bovine parainfluenza virus 3 (BPIV-3), and to combinations of these viruses, were investigated.
Based on weighted seroprevalences at induction (when animals were enrolled and initial samples collected), the percentages of the project population estimated to be seropositive were 24% for BoHV-1, 69% for BVDV-1, 89% for BRSV and 91% for BPIV-3.
For each of the four viruses, seropositivity at induction was associated with reduced risk of BRD (OR: 0.6–0.9), and seroincrease from induction to second blood sampling (35–60 days after induction) was associated with increased risk of BRD (OR: 1.3–1.5). Compared to animals that were seropositive for all four viruses at induction, animals were at progressively increased risk with increasing number of viruses for which they were seronegative; those seronegative for all four viruses were at greatest risk (OR: 2.4). Animals that seroincreased for one or more viruses from induction to second blood sampling were at increased risk (OR: 1.4–2.1) of BRD compared to animals that did not seroincrease for any viruses. Collectively these results confirm that prior exposure to these viruses is protective while exposure at or after feedlot entry increases the risk of development of BRD in feedlots. However, the modest increases in risk associated with seroincrease for each virus separately, and the progressive increases in risk with multiple viral exposures highlights the importance of concurrent infections in the aetiology of the BRD complex. These findings indicate that, while efficacious vaccines could aid in the control of BRD, vaccination against one of these viruses would not have large effects on population BRD incidence but vaccination against multiple viruses would be expected to result in greater reductions in incidence. The findings also confirm the multifactorial nature of BRD development, and indicate that multifaceted approaches in addition to efficacious vaccines against viruses will be required for substantial reductions in BRD incidence.
•The prevalence of BVDV-1 PI animals entering Australian feedlots was 0.24%.•BVDV-1 was detected by qPCR in 59% of feedlot pens.•BVDV-1 in the pen modestly increased the risk of BRD amongst animals ...in the pen.•A single qPCR test was useful in differentiating PI from TI animals.
Viruses play a key role in the complex aetiology of bovine respiratory disease (BRD). Bovine viral diarrhoea virus 1 (BVDV-1) is widespread in Australia and has been shown to contribute to BRD occurrence. As part of a prospective longitudinal study on BRD, effects of exposure to BVDV-1 on risk of BRD in Australian feedlot cattle were investigated. A total of 35,160 animals were enrolled at induction (when animals were identified and characteristics recorded), held in feedlot pens with other cattle (cohorts) and monitored for occurrence of BRD over the first 50days following induction. Biological samples collected from all animals were tested to determine which animals were persistently infected (PI) with BVDV-1. Data obtained from the Australian National Livestock Identification System database were used to determine which groups of animals that were together at the farm of origin and at 28days prior to induction (and were enrolled in the study) contained a PI animal and hence to identify animals that had probably been exposed to a PI animal prior to induction. Multi-level Bayesian logistic regression models were fitted to estimate the effects of exposure to BVDV-1 on the risk of occurrence of BRD.
Although only a total of 85 study animals (0.24%) were identified as being PI with BVDV-1, BVDV-1 was detected on quantitative polymerase chain reaction in 59% of cohorts. The PI animals were at moderately increased risk of BRD (OR 1.9; 95% credible interval 1.0–3.2). Exposure to BVDV-1 in the cohort was also associated with a moderately increased risk of BRD (OR 1.7; 95% credible interval 1.1–2.5) regardless of whether or not a PI animal was identified within the cohort. Additional analyses indicated that a single quantitative real-time PCR test is useful for distinguishing PI animals from transiently infected animals.
The results of the study suggest that removal of PI animals and/or vaccination, both before feedlot entry, would reduce the impact of BVDV-1 on BRD risk in cattle in Australian feedlots. Economic assessment of these strategies under Australian conditions is required.
•Population-level effects of risk factors for BRD in feedlot cattle were determined.•Risk factors with large effects were shared pen water, breed, mixing and move timing.•BVDV in the pen, prior group ...size and weight had moderate or modest effects.•82% of BRD incidence was attributed to management-related risk factors.
Results obtained from a nationwide longitudinal study were extended to estimate the population-level effects of selected risk factors on the incidence of bovine respiratory disease (BRD) during the first 50days at risk in medium-sized to large Australian feedlots. Population attributable fractions (PAF) and population attributable risks (PAR) were used to rank selected risk factors in order of importance from the perspective of the Australian feedlot industry within two mutually exclusive categories: ‘intervention’ risk factors had practical strategies that feedlot managers could implement to avoid exposure of cattle to adverse levels of the risk factor and a precise estimate of the population-level effect while ‘others’ did not. An alternative method was also used to quantify the expected effects of simultaneously preventing exposure to multiple management-related factors whilst not changing exposure to factors that were more difficult to modify.
The most important ‘intervention’ risk factors were shared pen water (PAF: 0.70, 95% credible interval: 0.45–0.83), breed (PAF: 0.67, 95% credible interval: 0.54–0.77), the animal’s prior lifetime history of mixing with cattle from other herds (PAF: 0.53, 95% credible interval: 0.30–0.69), timing of the animal’s move to the vicinity of the feedlot (PAF: 0.45, 95% credible interval: 0.17–0.68), the presence of Bovine viral diarrhoea virus 1 (BVDV-1) in the animal’s cohort (PAF: 0.30, 95% credible interval: 0.04–0.50), the number of study animals in the animal’s group 13days before induction (PAF: 0.30, 95% credible interval: 0.10–0.44) and induction weight (PAF: 0.16, 95% credible interval: 0.09–0.23). Other important risk factors identified and prioritised for further research were feedlot region, season of induction and cohort formation patterns.
An estimated 82% of BRD incidence was attributable to management-related risk factors, whereby the lowest risk category of a composite management-related variable comprised animals in the lowest risk category of at least four of the five component variables (shared pen water, mixing, move timing, BVDV-1 in the cohort and the number of animals in the animal’s group-13). This indicated that widespread adoption of appropriate interventions including ensuring pen water is not shared between pens, optimising animal mixing before induction, timing of the animal’s move to the vicinity of the feedlot, and group size prior to placing animals in feedlot pens, and avoiding BVDV-1 in cohorts could markedly reduce the incidence of BRD in medium-sized to large Australian feedlots.
Spectral index has been traditionally used to separate extragalactic radio sources into compact and extended populations, with the spectral transition placed variably between −0.4 and −0.6. We use ...high angular resolution data, measured from visibility of sources at the longest baseline of 4500 m of the Australia Telescope Compact Array (ATCA), for the Australia Telescope 20 GHz (AT20G) survey to obtain angular size information for over 94 per cent of AT20G sources. We confirm the previous AT20G result that due to the high survey frequency of 20 GHz, the source population is strongly dominated by compact sources (79 per cent). At 0.15-arcsec angular resolution limit, we show a very strong correlation between the compact and extended sources with flat and steep-spectrum sources respectively for spectral indices obtained between 1 and 5 GHz. Thus, we provide a firm physical basis for the traditional spectral classification into flat and steep-spectrum sources to select compact and extended sources. We find that for spectral indices between 1 and 5 GHz, the cut-offs at −0.4 and −0.5 are quite similar to the optimum cut-off of −0.46 and, hence, recommend the continued use of −0.5 for future studies.
We use the recently published redshift data to study the effect of spectral curvature on the redshift cut-off of compact active galactic nuclei (AGNs). Using spectral indices at different frequencies, we correct for the redshift effect and also produce rest-frame frequency spectra for compact sources for redshifts up to z∼ 5. We show that the spectra of most compact sources are flat to ∼30 GHz and then start to steepen. At higher frequencies, the spectra of both compact and extended sources are steep, so the use of spectral index does not separate the compact and extended source populations as well as in lower frequencies. We also find that due to spectral steepening at high frequencies, surveys of compact sources at higher frequencies (ν > 5 GHz) will have redshift cut-off due to spectral curvature but at frequencies below a few gigahertz, the surveys are not significantly affected by spectral curvature and, thus, the evidence for a strong redshift cut-off in AGNs found in lower frequency surveys is a real cut-off and not a result of K-correction.
ABSTRACT BACKGROUND Patients with cleft lip and/or palate can undergo numerous procedures to improve appearance, speech, dentition and hearing. We developed a cleft-specific patient-reported outcome ...instrument to facilitate rigorous international measurement and benchmarking. METHODS Data were collected from patients aged 8–29 years with cleft lip and/or palate at 30 hospitals in 12 countries between October 2014 and November 2016. Rasch measurement theory analysis was used to refine the scales and to examine reliability and validity. Normative CLEFT-Q values were computed for age, sex and cleft type. RESULTS Analysis led to the refinement of an eating and drinking checklist and 12 scales measuring appearance (of the face, nose, nostrils, teeth, lips, jaws and cleft lip scar), health-related quality of life (psychological, social, school, speech distress) and speech function. All scales met the requirements of the Rasch model. Analysis to explore differential item functioning by age, sex and country provided evidence to support the use of a common scoring algorithm for each scale for international use. Lower (worse) scores on CLEFT-Q scales were associated with having a speech problem, being unhappy with facial appearance, and needing future cleft-related treatments, providing evidence of construct validity. Normative values for age, sex and cleft type showed poorer outcomes associated with older age, female sex and having a visible cleft. INTERPRETATION The CLEFT-Q represents a rigorously developed instrument that can be used internationally to collect and compare evidence-based outcomes data from patients aged 8–29 years of age with cleft lip and/or palate.
Fast radio bursts (FRBs) are brief radio emissions from distant astronomical sources. Some are known to repeat, but most are single bursts. Nonrepeating FRB observations have had insufficient ...positional accuracy to localize them to an individual host galaxy. We report the interferometric localization of the single-pulse FRB 180924 to a position 4 kiloparsecs from the center of a luminous galaxy at redshift 0.3214. The burst has not been observed to repeat. The properties of the burst and its host are markedly different from those of the only other accurately localized FRB source. The integrated electron column density along the line of sight closely matches models of the intergalactic medium, indicating that some FRBs are clean probes of the baryonic component of the cosmic web.
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