Growth, persistence, and alkaloid levels of endophyte‐infected and endophyte‐free ryegrass pastures grazed by dairy cows in northern New Zealand

Abstract

A farm-scale trial was conducted over three years at the Dairying Research Corporation, Hamilton, New Zealand to compare the growth and persistence of endophyte-infected and endophytefree perennial ryegrass (Lolium perenne) pastures established with or without white clover (Trifolium repens), when rotationally grazed by dairy cows. Endophyte-free ryegrass areas were also undersown with endophyte-free seed in March and April of the second and third years, respectively. Average total herbage yields were similar for all treatments in each of the three years, ranging from 12.8 to 13.9 t DM ha -1 . Pasture growth rates in all treatments were lowest in the first summer/autumn after drilling, averaging 17 kg DM ha -1 day -1 for 90 days, coinciding with the highest herbage concentrations of lolitrem B (2.37 to 3.04 µg g -1 DM) in the highendophyte ryegrass. Ergovaline herbage concentrations rarely exceeded 1 µg g -1 DM and were highest (1.6 µg g -1 DM) in high-endophyte ryegrass pastures at the start of the third summer (December 1995), probably because of a high seed-head content (30% of DM). Contamination of endophyte-free ryegrass areas with volunteer endophyte-infected ryegrass was rapid, averaging 26, 41, and 50% of plants after the first, second, and third years from sowing, respectively. Further research is required to identify sources of this contamination and A 98065Received 21 December 1998; accepted 6 May 1999 management strategies to maintain purity of endophyte-free ryegrass or ryegrass containing novel endophytes.

Impact of novel endophytes in perennial ryegrass on herbage production and insect pests from pastures under dairy cow grazing in northern New Zealand

“…The seasonal trends of a summer/autumn peak in lolitrem B and ergovaline concentrations in 2005–2006, 2006–2007 and 2008–2009 (Figure ) follow those reported in the literature (Prestidge, ; Thom et al ., ; Bluett et al ., ), but in 2007–2008 summer trends were different when there was a prolonged drought from January to March 2008 (Table ). The current research also showed concentrations of epoxy‐janthitrems follow the same seasonal trends as lolitrem B, with a distinct peak in February of each year except for February 2008.…”

“…Ergovaline, an ergopeptine alkaloid, exacerbates heat stress especially in warm humid environments (Fletcher, ; Bluett et al ., ). Most New Zealand dairy cows graze pasture based on perennial ryegrass infected with Wild‐type endophyte and are, therefore, exposed to high levels of alkaloids in summer (Barker et al ., ; Thom et al ., ). This sometimes results in clinical ryegrass staggers and associated management difficulties and losses in milk production in dairy cows, which prompted the search for endophytes with different alkaloid profiles to Wild‐type that might give insect control without adverse effects on animal health and production.…”

Using Ecophysiology to Improve Farm Efficiency: Application in Temperate Dairy Grazing Systems

“…lolii (formerly Neotyphodium lolii, [60]). This endophyte produces high concentrations of the alkaloids lolitrem and ergovaline, especially in the summer/autumn dry conditions of northern New Zealand [61,62] where the majority of New Zealand's dairy cows were farmed. These alkaloids are concentrated in the base of the leaf sheath.…”

Endophyte infection influences disappearance of perennial ryegrass seed

“…As a result, new pastures sown to endophyte-free ryegrass in New Zealand often become dominated by endophyte-infected plants over time. In some cases rapid increases in endophyte infection can occur within 1 -3 years after pasture is sown (Prestidge et al 1984;Prestidge et al 1985;Popay et al 1999;Thom et al 1999). Such a rapid change must arise from infected seed, which may have been shed within the pasture prior to sowing or been brought in via animal dung (van Vught and Thom 1997).…”