Effects of a novel ryegrass endophyte on pasture production, dairy cow milk production and calf liveweight gain

Abstract

A 2-year evaluation of perennial ryegrass (Lolium perenne) infected with wild endophyte (Neotyphodium lolii), AR1 endophyte or no endophyte was carried out in Hamilton, New Zealand. In contrast to wild endophyte-infected ryegrass, AR1-infected ryegrass does not produce the alkaloids lolitrem B or ergovaline. Annual pasture production was similar across endophyte treatments, averaging 18.3 t DM/ha in year 1 and 13.8 t DM/ha in year 2, and ryegrass tiller density and botanical composition were unaffected by endophyte status. A combined analysis of 3 short-term milk production tests in late spring (Nov. 1999), summer (Jan. 2000) and autumn (Mar. 2000) in the first experiment, showed a 6.7% advantage in milk production to cows grazing AR1-infected ryegrass compared with those grazing wild endophyte-infected ryegrass pastures (P<0.05). Milk composition was similar in all test periods and ryegrass staggers was not observed on any treatment. In a second experiment, weaned dairy calves were continuously stocked on the pastures described above from late spring 2000 to autumn 2001 and grazed to a mean sward height of 5 cm. Average calf liveweight gain and total liveweight gain per hectare were similar across treatments over the 5-month period, averaging 0.8 kg/calf.day and 822 kg/ha, respectively. Calves grazing wild endophyte-infected ryegrass developed mild ryegrass staggers in January and February, coinciding with a peak lolitrem B concentration in this experiment of 2.3 mg/kg DM, while those grazing AR1-infected or endophyte-free ryegrass pastures did not develop staggers. Information is also presented on herbage and alkaloid intake, blood plasma prolactin concentration, and cow temperature and respiration rate. Results from this initial evaluation under dairying indicate that AR1-infected ryegrass can produce similar pasture yields as wild endophyte-infected ryegrass, while offering small improvements in milk yield with no incidence of ryegrass staggers in grazing animals.

Indole-Diterpene Biosynthetic Capability ofEpichloëEndophytes as Predicted byltmGene Analysis

“…Field trials with AR1-infected perennial ryegrass showed improved animal productivity over common toxic endophyte (lolitrem B producer)-infected perennial ryegrass, with no evidence of animal toxicity such as ryegrass staggers (1,2). Indole-diterpene precursors of lolitrem B could provide a selective advantage to the grass that is not related to animal toxicity but may involve protection against insects, such as that found with the nontremorgenic indole-diteprene nodulisporic acid from Nodulisporium species (7).…”

“…Artificially inoculated associations of these endophytes with elite tall fescue (4) and perennial ryegrass cultivars (16) have been commercially established and shown to enhance animal productivity, while alleviating the negative responses such as fescue toxicosis and ryegrass staggers (1,2,50,51,68).…”

Defensive mutualism between plants and endophytic fungi?

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Effects of novel and wild-type endophytes in perennial ryegrass on cow health and production

“…At lower median lolitrem B levels of 2.9 mg/kg DM only 1 of the 15 cows grazing Wild-type endophyte showed clinical signs of RGS in autumn 2007. These data suggest RGS in rotationally grazing dairy cows can occur at lolitrem B concentrations of about 2.5 mg/kg DM or greater, but the incidence is affected by pasture composition, Thom et al New Zealand Veterinary Journal 61(2), 2013 95 environmental conditions, grazing management and individual differences in animal grazing behaviour, that influence the intake of lolitrem B by the cow (Bluett et al 2005b). The severity of RGS may be influenced by synergistic interactions between ergovaline and lolitrem B (Fletcher and Easton 1997;Bluett et al 2005b), and milk yield may be reduced even when cows exhibit only slight signs of RGS with a score of 1 or less (Thom et al 2010).…”

“…These data suggest RGS in rotationally grazing dairy cows can occur at lolitrem B concentrations of about 2.5 mg/kg DM or greater, but the incidence is affected by pasture composition, Thom et al New Zealand Veterinary Journal 61(2), 2013 95 environmental conditions, grazing management and individual differences in animal grazing behaviour, that influence the intake of lolitrem B by the cow (Bluett et al 2005b). The severity of RGS may be influenced by synergistic interactions between ergovaline and lolitrem B (Fletcher and Easton 1997;Bluett et al 2005b), and milk yield may be reduced even when cows exhibit only slight signs of RGS with a score of 1 or less (Thom et al 2010). The work of Finch et al (2007) and Imlach et al (2008), using the mouse model, suggested that lolitrem B induced tremors in livestock by inhibiting regulators of cellular excitability known as BK channels.…”