New Zealand Journal of Agricultural Research abstracts
Growth, persistence, and alkaloid levels of endophyte-infected and
endophyte-free ryegrass pastures grazed by dairy cows in northern New
Zealand
E. R. THOM
D. A. CLARK
C. D. WAUGH
Dairying Research Corporation
Private Bag 3123
Hamilton, 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 endophyte-free 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 ug g-1 DM) in the
high-endophyte ryegrass. Ergovaline herbage concentrations rarely exceeded 1 ug
g-1 DM and were highest (1.6 ug 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 management strategies to maintain purity of
endophyte-free ryegrass or ryegrass containing novel endophytes.
Keywords herbage accumulation; botanical composition;
seasonal changes; endophyte content; white clover content; lolitrem B;
ergovaline; endophyte contamination; Lolium perenne
New Zealand Journal of Agricultural Research, 1999, Vol. 42: 241-253
0028-8233/99/4203-0241 $7.00/0 (c) The Royal Society of New Zealand
1999
PDF file of entire paper: medium quality (1056K); (scanned from paper original: notes about this process)
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