There is some evidence that superheating destroys the antirachitic effect of irradiation. In order to test this point further we have compared over a period of 10 weeks the growth performance of rats which were receiving a rachitic ration with that of animals receiving (1) similar rations which had been irradiated; and (2) the irradiated ration which had been subsequently superheated. This rachitic ration which consisted of a mixture of grains was finely ground, mixed with distilled water and heated until it was of a thick gelatinous consistency. Since even at 15 pounds pressure mixtures of this consistency seldom reach throughout temperatures above 97° C., it was thought that results with these rachitic rations might not be valid. Therefore, we have tested the effects of the addition to the ration of (1) boiled milk; (2) irradiated boiled milk; and (3) irradiated milk which was subsequently autoclaved. In order to test further the effect of superheating on the antirachitic properties of milk, we have used in the rachitic ration comparable amounts of evaporated milk, as well as evaporated milk supplemented with calcium phosphate, thereby ruling out the influence of the possible calcium deficiency of the evaporated milk. The rickets ration was irradiated in thin layers (⅛ inch) for ½ hour at a distance of 2 feet. Part of this was then autoclaved at 15 pounds for 6 hours. The milk was irradiated in ¼ inch layers for 20 minutes at a distance of 2 feet. Before autoclaving this was diluted with distilled water and heated at 15 pounds pressure for one hour. The results of the investigation indicate that superheating, at least to the extent involved in the experiment, does not affect the antirachitic properties of food. This is shown not only by the animals which received the irradiated milks, but by those receiving the evaporated milk as well.
This study aimed to determine the frequency and molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) from Australian animals and whether animal-derived MRSA was similar to that from Australian veterinarians. A total of 1,080 clinical coagulase positive Staphylococcus isolates from Australian animals were collected during 2013. Sixteen (4%) of 360 S. aureus isolates were MRSA. Most MRSA came from companion animals, while none came from livestock. MRSA isolates were characterized using whole genome sequencing. ST22-IV (EMRSA-15) was the most common clone in dogs and cats. Clonal complex (CC) 8 was most common in horses. Most ST22-IV isolates were resistant to ciprofloxacin. Animal-derived MRSA genomes were interrogated for the presence of host-specific genetic markers (staphylokinase gene [scn], chemotaxis-inhibiting proteins gene [chp], staphylococcal complement inhibitor gene [sak], enterotoxin A gene [sea], and Von Willebrand Factor binding protein gene [vwb]). A subset of MRSA genomes previously collected from Australian veterinarians was also interrogated. There was no clear pattern in the distribution of host-specific markers among animal and veterinarian isolates. Animal- and veterinarian-derived MRSA were intermingled in the phylogenetic tree. The absence of MRSA in Australian livestock is in stark contrast with its presence in livestock from other countries. Possible explanations include Australia's geographic isolation, the absence of live animal importation into Australia, and most notably, the restrictions placed on the use of antimicrobials of critical importance in Australian livestock.
Infection with Pasteurella multocida represents a significant economic threat to Australian pig producers, yet our knowledge of its antimicrobial susceptibilities is lagging, and genomic characterization of P. multocida strains associated with porcine lower respiratory disease is internationally scarce. This study utilized high-throughput robotics to phenotypically and genetically characterize an industry-wide collection of 252 clinical P. multocida isolates that were recovered between 2014 and 2019. Overall, antimicrobial resistance was found to be low, with clinical resistance below 1% for all tested antimicrobials except those from the tetracycline class. Five dominant sequence types, representing 64.8% of all isolates, were identified; they were disseminated across farms and had previously been detected in various animal hosts and countries. P. multocida in Australian farms remain controllable via current antimicrobial therapeutic protocols. The identification of highly dominant, interspecies-infecting strains provides insight into the epidemiology of the opportunistic pathogen, and it highlights a biosecurity threat to the Australian livestock industry. IMPORTANCE Pasteurellosis is rated by the World Animal Health Organisation (OIE) as a high-impact disease in livestock. Although it is well understood in many host-disease contexts, our understanding of the organism in porcine respiratory disease is limited. Given its high frequency of involvement in porcine respiratory disease complex (PRDC), it is important that we are aware of its antimicrobial susceptibilities so that we can respond quickly and appropriately with antimicrobial therapy. Genetic insights about the organism can help us to better understand its epidemiology and inform our biosecurity practices and prophylactic management.
SUMMARY This study aims to describe in detail the temporal dynamics of E. coli O157 shedding and risk factors for shedding in a grass-fed beef herd. During a 9-month period, 23 beef cows were sampled twice a week (58 sampling points) and E. coli O157 was enumerated from faecal samples. Isolates were screened by PCR for presence of rfb E, stx 1 and stx 2 . The prevalence per sampling day ranged from 0% to 57%. This study demonstrates that many members of the herd were concurrently shedding E. coli O157. Occurrence of rainfall ( P < 0·01), feeding silage ( P < 0·01) and lactating ( P < 0·01) were found to be predictors of shedding. Moving cattle to a new paddock had a negative effect on shedding. This approach, based on short-interval sampling, confirms the known variability of shedding within a herd and highlights that high shedding events are rare.
Abstract A time series of estimates of irrigated area was developed for the Lower Rio Grande valley ( LRG ) in N ew M exico from the 1970s to present day. The objective of the project was to develop an independent, accurate, and scientifically justifiable evaluation of irrigated area in the region for the period spanning from the mid‐1970s to the present. These area estimates were used in support of groundwater modeling of the LRG region, as well as for other analyses. This study used a remote‐sensing‐based methodology to evaluate overall irrigated area within the LRG . We applied a methodology that involved the normalization of vegetation indices derived from satellite imagery to get a more accurate estimation of irrigated area across multiple time periods and multiple L andsat platforms. The normalization allows more accurate evaluation of vegetation index data that span several decades. An accuracy assessment of the methodology and results from this study was performed using field‐collected crop data from the 2008 growing season. The comparisons with field data indicate that the accuracy of the remote‐sensing‐based estimates of historical irrigated area is very good, with rates of false positives (areas identified as irrigated that are not truly irrigated) of only about 4%, and rates of false negatives (areas identified as not irrigated that are truly irrigated) in the range of 0.6‐2.0%.
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