Fluctuations in the concentration of ergovaline and lolitrem B produced by the wild-type endophyte (Neotyphodium lolii) in perennial ryegrass (Lolium perenne) pasture

2011 ◽  
Vol 51 (12) ◽  
pp. 1098 ◽  
Author(s):  
K. F. M. Reed ◽  
Z. N. Nie ◽  
L. V. Walker ◽  
G. Kearney

Mammalian toxins produced by the wild-type endophyte, Neotyphodium lolii, in perennial ryegrass (PRG) pasture cause production losses and animal health and welfare problems in livestock. Managing this risk is limited by the lack of information on fluctuations in the concentration of toxin in Australian pasture. We investigated how the toxin concentrations may be related to recent observations of weather. Swards sown from common seedlots of two cultivars of wild endophyte-infected PRG, grazed short by sheep, were sampled at 2–4 weekly intervals from spring to autumn at two sites in Victoria. The highest concentration of ergovaline and lolitrem B was observed at Hamilton, the site with the longer-growing season. The concentration of ergovaline peaked in early summer, coinciding with seed development, and declined through summer, before increasing with the commencement of autumn growth. The concentration of lolitrem B remained low in summer, then rose in autumn. Variation between the two cultivars in the concentration of toxins was small and rarely significant. The concentration of ergovaline declined as the mean daily maximum temperature over the preceding 1–5 days increased. Similarly, for lolitrem B, the concentration declined over the temperature range 12−20°C, from 1.3 to 0.3 mg/kg. At Hamilton, where solar radiation and soil temperature were recorded, both were superior to maximum temperature for predicting lolitrem B. Serial sampling of PRG from old naturalised pasture on seven farms across south-eastern Australia found two seasonal peaks for both alkaloids in most pastures. The concentration of ergovaline reached or exceeded tolerance levels for livestock in 23 of 43 samples, compared with 5 of 43 for lolitrem B. Ergovaline concentrations initially peaked (at 1.0–1.6 mg/kg) when mature reproductive material was present (coinciding with peduncle elongation and seed development). In pastures with low grazing pressure, i.e. where growth was allowed to continue through summer, ergovaline concentration was relatively low (<0.7 mg/kg) but in a hard-grazed pasture (sward height 3 cm), the ergovaline concentration was greater (up to 1.1 mg/kg). Concentration of lolitrem B also peaked in December, except on pasture where growth continued through summer. High concentrations of lolitrem B associated with neurotoxic signs in sheep (viz. 2.4–3.9 mg/kg) were observed only in mid-summer and autumn, and only if conditions favoured growth or where close grazing by sheep left the crown as the dominant source of herbage.

1985 ◽  
Vol 25 (4) ◽  
pp. 734 ◽  
Author(s):  
GR Saul ◽  
PC Flinn

Nine groups of four Hereford heifers (mean � s.e. liveweight 223 � 3.1 kg), drank water containing either high (650 ppm) or low (10 ppm) magnesium concentrations combined with varying levels (5000,7000,9000, 11 000 ppm) of total soluble salts (TSS) for 79 days. At each level of TSS, high magnesium treatments were obtained by replacing 2550 pprn sodium chloride with an equal amount of magnesium chloride. A control group drank water containing 10 pprn Mg and 2 10 pprn TSS. All animals werq kept in feedlots and fed on hay ad libitum. Mean daily maximum temperature and mean daily evaporation during the experiment were 23�C and 4.6 mm, respectively. At the various TSS levels, the presence or absence of high levels of magnesium did not significantly affect liveweight gain, feed intake or animal health which suggests that the adverse effects of sodium and magnesium are similar. However, during the first 51 days of the experiment, heifers drinking water containing 11 000 pprn TSS and 650 ppm Mg lost weight and ate less than all other groups. Compared with control animals, those drinking water containing more than 5000 pprn TSS showed reduced liveweight gain (P<0.05) and feed intake during the first 5 1 days of the experiment, but this effect diminished as the experiment progressed. Overall, a TSS level of 5000 ppm caused a large but non-significant reduction in liveweight gain (36.3 v. 25.9 kg) over the 79-day period while a level of 11 000 ppm reduced liveweight by 49% (36.3 v 18.5 kg, P < 0.05)


1999 ◽  
Vol 7 ◽  
pp. 133-139
Author(s):  
L.R. Fletcher

Ryegrass/endophyte associations have been developed which produce peramine, but not the endophyte toxins ergovaline or lolitrem B. Sheep grazing these ryegrasses in small paddocks and in a systems trial over three years gained weight as rapidly as those grazing endophyte-free ryegrass, and showed none of the adverse responses associated with grazing ryegrass naturally infected with wild-type endophyte (Neotyphodium lolii). Growth rates, rectal temperatures, respiration rates, serum prolactin concentrations, ryegrass staggers scores and scores for dag burdens were equivalent for the selected endophyte and nil endophyte treatments, whereas sheep grazing the wild-type endophyte treatment were adversely affected for all parameters. This was reflected in calculated gross margins for the systems trial of only $605 per hectare for the wild-type endophyte treatment compared with over $700 per hectare for each of the other treatments. To date there have been no conclusive studies of non-toxic endophyte with cattle. Keywords: AR1, dags, endophyte, ergovaline, liveweight gain, lolitrem B, Lolium perenne, Neotyphodium, peramine, perennial ryegrass, prolactin, sheep


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Emily J. Wilkins ◽  
Peter D. Howe ◽  
Jordan W. Smith

AbstractDaily weather affects total visitation to parks and protected areas, as well as visitors’ experiences. However, it is unknown if and how visitors change their spatial behavior within a park due to daily weather conditions. We investigated the impact of daily maximum temperature and precipitation on summer visitation patterns within 110 U.S. National Park Service units. We connected 489,061 geotagged Flickr photos to daily weather, as well as visitors’ elevation and distance to amenities (i.e., roads, waterbodies, parking areas, and buildings). We compared visitor behavior on cold, average, and hot days, and on days with precipitation compared to days without precipitation, across fourteen ecoregions within the continental U.S. Our results suggest daily weather impacts where visitors go within parks, and the effect of weather differs substantially by ecoregion. In most ecoregions, visitors stayed closer to infrastructure on rainy days. Temperature also affects visitors’ spatial behavior within parks, but there was not a consistent trend across ecoregions. Importantly, parks in some ecoregions contain more microclimates than others, which may allow visitors to adapt to unfavorable conditions. These findings suggest visitors’ spatial behavior in parks may change in the future due to the increasing frequency of hot summer days.


2014 ◽  
Vol 53 (9) ◽  
pp. 2148-2162 ◽  
Author(s):  
Bárbara Tencer ◽  
Andrew Weaver ◽  
Francis Zwiers

AbstractThe occurrence of individual extremes such as temperature and precipitation extremes can have a great impact on the environment. Agriculture, energy demands, and human health, among other activities, can be affected by extremely high or low temperatures and by extremely dry or wet conditions. The simultaneous or proximate occurrence of both types of extremes could lead to even more profound consequences, however. For example, a dry period can have more negative consequences on agriculture if it is concomitant with or followed by a period of extremely high temperatures. This study analyzes the joint occurrence of very wet conditions and high/low temperature events at stations in Canada. More than one-half of the stations showed a significant positive relationship at the daily time scale between warm nights (daily minimum temperature greater than the 90th percentile) or warm days (daily maximum temperature above the 90th percentile) and heavy-precipitation events (daily precipitation exceeding the 75th percentile), with the greater frequencies found for the east and southwest coasts during autumn and winter. Cold days (daily maximum temperature below the 10th percentile) occur together with intense precipitation more frequently during spring and summer. Simulations by regional climate models show good agreement with observations in the seasonal and spatial variability of the joint distribution, especially when an ensemble of simulations was used.


2005 ◽  
Vol 18 (23) ◽  
pp. 5011-5023 ◽  
Author(s):  
L. A. Vincent ◽  
T. C. Peterson ◽  
V. R. Barros ◽  
M. B. Marino ◽  
M. Rusticucci ◽  
...  

Abstract A workshop on enhancing climate change indices in South America was held in Maceió, Brazil, in August 2004. Scientists from eight southern countries brought daily climatological data from their region for a meticulous assessment of data quality and homogeneity, and for the preparation of climate change indices that can be used for analyses of changes in climate extremes. This study presents an examination of the trends over 1960–2000 in the indices of daily temperature extremes. The results indicate no consistent changes in the indices based on daily maximum temperature while significant trends were found in the indices based on daily minimum temperature. Significant increasing trends in the percentage of warm nights and decreasing trends in the percentage of cold nights were observed at many stations. It seems that this warming is mostly due to more warm nights and fewer cold nights during the summer (December–February) and fall (March–May). The stations with significant trends appear to be located closer to the west and east coasts of South America.


2021 ◽  
Author(s):  
Mastawesha Misganaw Engdaw ◽  
Andrew Ballinger ◽  
Gabriele Hegerl ◽  
Andrea Steiner

&lt;p&gt;In this study, we aim at quantifying the contribution of different forcings to changes in temperature extremes over 1981&amp;#8211;2020 using CMIP6 climate model simulations. We first assess the changes in extreme hot and cold temperatures defined as days below 10% and above 90% of daily minimum temperature (TN10 and TN90) and daily maximum temperature (TX10 and TX90). We compute the change in percentage of extreme days per season for October-March (ONDJFM) and April-September (AMJJAS). Spatial and temporal trends are quantified using multi-model mean of all-forcings simulations. The same indices will be computed from aerosols-, greenhouse gases- and natural-only forcing simulations. The trends estimated from all-forcings simulations are then attributed to different forcings (aerosols-, greenhouse gases-, and natural-only) by considering uncertainties not only in amplitude but also in response patterns of climate models. The new statistical approach to climate change detection and attribution method by Ribes et al. (2017) is used to quantify the contribution of human-induced climate change. Preliminary results of the attribution analysis show that anthropogenic climate change has the largest contribution to the changes in temperature extremes in different regions of the world.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Keywords:&lt;/strong&gt; climate change, temperature, extreme events, attribution, CMIP6&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgement:&lt;/strong&gt; This work was funded by the Austrian Science Fund (FWF) under Research Grant W1256 (Doctoral Programme Climate Change: Uncertainties, Thresholds and Coping Strategies)&lt;/p&gt;


2017 ◽  
Vol 145 (12) ◽  
pp. 2603-2610 ◽  
Author(s):  
A. MILAZZO ◽  
L. C. GILES ◽  
Y. ZHANG ◽  
A. P. KOEHLER ◽  
J. E. HILLER ◽  
...  

SUMMARYCampylobacterspp. is a commonly reported food-borne disease with major consequences for morbidity. In conjunction with predicted increases in temperature, proliferation in the survival of microorganisms in hotter environments is expected. This is likely to lead, in turn, to an increase in contamination of food and water and a rise in numbers of cases of infectious gastroenteritis. This study assessed the relationship ofCampylobacterspp. with temperature and heatwaves, in Adelaide, South Australia.We estimated the effect of (i) maximum temperature and (ii) heatwaves on dailyCampylobactercases during the warm seasons (1 October to 31 March) from 1990 to 2012 using Poisson regression models.There was no evidence of a substantive effect of maximum temperature per 1 °C rise (incidence rate ratio (IRR) 0·995, 95% confidence interval (95% CI) 0·993–0·997) nor heatwaves (IRR 0·906, 95% CI 0·800–1·026) onCampylobactercases. In relation to heatwave intensity, which is the daily maximum temperature during a heatwave, notifications decreased by 19% within a temperature range of 39–40·9 °C (IRR 0·811, 95% CI 0·692–0·952). We found little evidence of an increase in risk and lack of association betweenCampylobactercases and temperature or heatwaves in the warm seasons. Heatwave intensity may play a role in that notifications decreased with higher temperatures. Further examination of the role of behavioural and environmental factors in an effort to reduce the risk of increasedCampylobactercases is warranted.


2007 ◽  
Vol 13 ◽  
pp. 399-402
Author(s):  
L. Blythe ◽  
C. Estill ◽  
J. Males ◽  
A.M. Craig

Perennial ryegrass (Lolium perenne) straw is used as a feed for livestock and horses. Some straw is infected with the endophyte, Neotyphodium lolii, which produces lolitrem tremorgens. Ingesting of the toxin produces clinical "ryegrass staggers." A 28 day feeding trail was conducted using 61 Black Angus, pure and crossbred cattle. The cattle were fed one of three levels of lolitrem B in chopped perennial ryegrass straw ranging from 0 ppb up to 3058 ppb. Four Japanese Wagyu crossbred cattle were fed chopped ryegrass straw containing 1400 ppb lolitrem B. The cattle were evaluated and scored twice a day for clinical signs of gait difficulties. Cattle consuming 1400 ppb lolitrem B did not show any overt clinical signs. After 14 days, 7 out of 15 cattle in the 1954 ppb lolitrem B group showed clinical signs of ataxia, stiffness, and tremors as seen in ryegrass staggers. All of the cattle in the positive control group of up to 3058 ppb lolitrem B with a 4 week mean of 2574 ppb developed clinical signs of staggers. None of the Wagyu cattle at 1400 ppb lolitrem B developed clinical signs. A dose response curve was developed based on the results of this study coupled with a prior study for use in the testing laboratory. Keywords: lolitrem B, perennial ryegrass, Lolium perenne, endophyte fungus, Neotyphodium lolii, cattle, threshold levels


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