New Zealand Journal of
Agricultural Research abstracts
Effects of perennial ryegrass
infected with either AR1 or wild endophyte on dairy production in the
Waikato
S. J. Bluett
E. R. Thom
D. A. Clark
K. A. Macdonald
E. M. K. Minneé
Dexcel
Private Bag 3221
Hamilton, New Zealand
stephanie.bluett@dexcel.co.nz
Abstract A
3-year farmlet experiment was carried out at Dexcel, Hamilton to
compare the effects of ryegrass infected with either AR1 (no lolitrem B
or ergovaline production) or wild endophyte on milksolids production
and cow health. Two farmlets (7 ha each) were managed as
self-contained systems with cows grazing rotationally from September
2000 to May 2003, with 2.6 cows ha–1
in 2000/01 and 3.0 cows ha–1
in 2001/02 and 2002/03. AR1-infected ryegrass pastures remained free of
contamination from volunteer wild-endophyte-infected ryegrass plants
for at least 3 years after sowing. Mean annual pasture production and
ryegrass tiller density were similar for both AR1- and
wild-endophyte-infected ryegrass farmlets in 3 years, with low numbers
of black beetle. A combined analysis of the three lactations data
showed that cows grazing AR1-infected ryegrass pastures produced 8.9%
more total milksolids than cows grazing wild-endophyte-infected
pastures (318 versus 292 kg cow–1,
SED = 9.2, P
= 0.006). The difference between treatments averaged across lactations
was 0.1 kg milksolids cow–1
day–1,
but the magnitude of the difference varied from week to week. This
highlighted the benefits of evaluating the effects of endophyte strain
over the entire lactation and for consecutive years, in order to
include effects of seasonal variations in alkaloid concentration. Milk
composition was similar for both treatments in all lactations. Ryegrass
staggers occurred in cows grazing wild-endophyte-infected pastures in
January 2001, coinciding with the highest concentrations of lolitrem B
over the three lactations (>3.5 mg kg–1
DM). Cow body temperatures, respiration rates and plasma prolactin
concentrations measured during periods of heat stress were only
occasionally affected by endophyte treatment. Results from this 3-year
farmlet evaluation demonstrate that renovating pastures with
AR1-infected perennial ryegrass can offer significant improvements in
milksolids production and elimination of ryegrass staggers.
Keywords alkaloids;
cow temperature; ergovaline; heat stress; lolitrem B; Lolium
perenne; milksolids production; Neotyphodium
lolii; novel endophyte; pasture
production; peramine; plasma prolactin; ryegrass staggers
A04082; Received 1 August 2004;
accepted 16 February 2005; Online publication date 30 May 2005
New Zealand Journal of
Agricultural Research, 2005, Vol. 48:
197–212
0028–8233/05/4802–0197 © The Royal Society of New
Zealand 2005
PDF file of entire paper: Print-quality
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