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Hamilton, Australia

Reed K.F.M.,Reed Pasture Science | Mace W.J.,Agresearch Ltd. | Walker L.V.,Southern Scientific Services | Fletcher L.R.,Agresearch Ltd.
Animal Production Science | Year: 2016

Perennial ryegrass (PRG) was analysed for alkaloids associated with the expression of perennial ryegrass endophyte toxicosis (PRGT) in south-east Australia. Over two seasons, the PRG cultivar Samson ('high endophyte', viz. naturally infected with a wild-type strain of Epichloë festucae var. lolii) was sampled on five occasions during November to May at four farms in Victoria and at Lincoln, New Zealand. Endophyte frequency in the populations was 77-100%. PRG was also sampled from 20 Victorian and Tasmanian farm pastures where stock were experiencing PRGT (endophyte infection frequencies of 87-100%). The Victorian summer of 2010-11 was atypically moist; pasture remained green. Lolitrem B was consistently high at Lincoln and 2-3 times that observed in Victorian samples of isogenetic PRG, or in PRG causing PRGT; it was the dominant toxin in 2011 with concentrations commonly exceeding the tolerance level of 1.8 mg/kg. In the following year, one with a more typical summer, ergovaline was the dominant toxin. Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS) was carried out to determine indole diterpene intermediates in the lolitrem B biosynthesis pathway and for ergot alkaloid intermediates in the ergovaline pathway. The values for lolitrem B determined by LC-MS/MS correlated strongly with those obtained using high pressure liquid chromatography. In both Years 1 and 2, significantly higher expression was observed in the Lincoln relative to Victorian samples of PRG for paspaline, terpendole C, lolitrem E, lolitrem B and lolitrem F. For the ergot alkaloids, significant differences were not apparent between Victorian and Lincoln samples in Year 1. In Year 2, LC-MS/MS results showed ergovaline concentrations were greater in Victorian samples. In addition to endophyte-produced toxins, ergot alkaloids produced by Claviceps purpurea (ergotamine, ergocryptine and ergocornine) were detected in grass samples on 6/27 occasions. Some unidentified metabolites were noted in both Victorian and Lincoln samples. The effects of ingested vaso-constrictive ergot alkaloids combined with that of high solar radiation on ruminants' heat load are considered most important with respect to the occasionally severe expression of PRGT in Australia. © 2016 CSIRO. Source


The development and use of perennial ryegrass (Lolium perenne L.), cocksfoot (Dactylis glomerata L.), phalaris (Phalaris aquatica L.) and tall fescue (Lolium arundinaceum Darbysh.) in the high-rainfall zone and the wheat-sheep zone is reviewed through the pastoral era of extensive grazing (from European settlement to ∼1930), the expansive era of pasture improvement (1930-80) and in the modern era. Their adoption, in conjunction with inoculated clover seed, rose steadily in specifically Australian systems of animal production, designed with an appreciation of the environment, and aided by technical developments such as single-disc and aerial spreaders for mineral fertiliser, chemical fallowing and direct-drilling. These species remain vital contributors to the competitive productivity of Australia's cattle and sheep industries. Perennial ryegrass (∼6Mha by 1994) and cocksfoot emerged as the most important after a wide range of species was introduced through the 19th Century; many of these became naturalised. Regional strains of perennial ryegrass were subsequently selected for commercialisation in Victoria, New South Wales and Tasmania. In the modern era, persistent ecotypes were harnessed to breed persistent cultivars. Vision to both improve grass persistence and extend the area of adaptation encouraged the adoption of phalaris (∼2.7Mha by 2009) and, to a lesser extent, early-flowering types of cocksfoot and tall fescue, particularly for the marginal-rainfall, wheat-sheep zone. The sowing of grass and clover seed expanded after the wide adoption of superphosphate, which became recognised as essential for correcting the severe deficiency of soil phosphorus and nitrogen associated with ancient, intensely weathered soils. The initial and dramatic response of clover to superphosphate increased farm revenue, so fostering a phase in which perennial grasses could be successfully sown, due to having the benefit of (biologically fixed) nitrogen. The influence of European practice, agricultural societies, the Welsh Plant Breeding Station, CSIRO, universities, state Departments of Agriculture, collaborative arrangements and individuals that nurtured and managed pasture technology, plant breeding, cultivar registration and evaluation are outlined. Future considerations emerging from the review include monitoring the national pasture inventory, promotion of the great potential for increasing livestock carrying capacity, cultivar discrimination and information, relevance of models, and national coordination of collaborative research. © CSIRO 2014. Source


Hamilton L.J.,P.O. Box 537 | Reed K.F.M.,Reed Pasture Science | Leach E.M.A.,64 Banambila Street | Brockwell J.,CSIRO
Crop and Pasture Science | Year: 2015

Field and glasshouse experiments confirmed the occurrence of boron (B) deficiency in subterranean clover (Trifolium subterraneum L.) pasture in eastern Victoria. Diminished productivity was linked to the small-seededness of clover and the poor effectiveness of clover root-nodule bacteria (rhizobia, Rhizobium leguminosarum bv. trifolii). Productivity, especially of clover and clover seed, increased following applications of up to 6 kg B ha-1 (P<0.001). The response was delayed, occurring several years after the initial application of B, unless the land was resown with fresh clover seed inoculated with an effective strain of rhizobia. B deficiency in the nodulated legume induced conditions within the plant and or its rhizobia that led to impaired nitrogen (N2) fixation. Glasshouse research indicated that populations of soil-borne rhizobia taken from B-deficient soils were poorly effective in N2 fixation and that rhizobia from soils growing subterranean clover cv. Leura were significantly less effective (P<0.05) than rhizobia from a soil growing cv. Mt Barker. Additionally, subterranean clover seed generated in B-deficient soils was at least one-third smaller than the seed of commercial seed but responded to inoculation with effective rhizobia. This indicated that any symbiotic malfunction of clover from B-deficient soils was not due to an inability to respond to nitrogen per se. On the other hand, cv. Leura from B-deficient soils fixed significantly less N2 than commercial cv. Leura when each was inoculated with rhizobia from B-deficient soils. © CSIRO 2015. Source


Combs M.D.A.,Charles Sturt University | Rendell D.,Livestock Logic Ltd | Reed K.F.M.,Reed Pasture Science | Mace W.J.,Agresearch Ltd. | Quinn J.C.,Charles Sturt University
Australian Veterinary Journal | Year: 2014

Case report: Perennial ryegrass toxicosis (PRGT) is a common disease entity in Australia, presenting as an association of clinical signs including alterations in normal behavioural, ataxia ('staggers'), ill thrift and gastrointestinal dysfunction ('scours'). Clinical signs can range in severity from mild (gait abnormalities and failure to thrive) to severe (seizures, lateral recumbency and death). Presentation across the flock is usually highly variable. PRGT is caused by toxins produced by the endophytic fungus Neotyphodium lolii, a symbiont of perennial ryegrass that is present in pastures across the temperate regions of Australia and Tasmania. A particular feature of PRGT in Australia is the occasional occurrence of large-scale sheep losses, suggesting other factors are influencing mortality rates compared with other PRGT risk zones such as North America and New Zealand. During 2011, producers in the state of Victoria experienced a mild outbreak of PRGT that affected large numbers of animals but with limited mortalities. Clinical samples taken from affected sheep showed a high incidence of dehydration and electrolyte abnormalities. Conclusion: We speculate that changes in hydration status may be a contributory aetiological factor in those years in which high numbers of deaths are associated with PRGT outbreaks in Australia. © 2014 Australian Veterinary Association. Source


Reed K.F.M.,Reed Pasture Science | Cummins L.J.,Ivanhoe | Moore D.D.,Biomin Australia Pty. Ltd. | Moore D.D.,University of Queensland | Clark A.J.,Allan Clark Thoroughbred Racing
Animal Production Science | Year: 2011

During February-April, Coopworth ewe lambs grazing a pasture dominated by naturalised perennial ryegrass (PRG) exhibited slight signs of ill-thrift and heat stress. PRG represented 85% of the herbage; 90% of the PRG population was infected with Neotyphodium endophyte. Concentrations of ergovaline and lolitrem B in perennial ryegrass were each within the range 0.5-1.0 mg/kg DM during this period. Two groups of 30 lambs rotated weekly between two paddocks that offered 6 t DM/ha of mature, low-quality pasture. They received an allowance of crushed barley and peas (80:20) at 100 g/head per day. One group was treated with a mycotoxin deactivator, Mycofix® Plus, mixed into their mash during processing (5 g/100 g). No sign of 'staggers' was observed in the lambs at any time. Lambs with access to Mycofix Plus made great use of shade; their occupancy of shade increased steeply with ambient temperature over the range 18-38°C (P < 0.001). For the control group, occupancy of shade was low (P < 0.001) and independent of temperature (P < 0.001). Instead of using shade on hot days, the control lambs whose respiration rate was higher than treated ewes (P < 0.001) commonly stood by the wire fence, huddled in the open. Over the first 56 days of treatment, while pasture remained dry, weight change in control and treated lambs was -13 and +16 g/day, respectively (P < 0.010). The need for greater investigation of the effects of endophyte alkaloids on livestock is discussed. © CSIRO 2011. Source

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