The effect of endophyte alkaloids on diet selection by sheep
G.P. COSGROVE, C.B. ANDERSON, M. PHILLOT, D. NYFELER, D.E. HUME,
A.J. PARSONS AND G.A. LANE
AgResearch Grasslands, PB 11008, Palmerston North.
NZSAP 2002 Abstract No. 42
Proceedings of the New Zealand Society of Animal Production 62:
167-170
Sheep have a strong preference for clover in summer. One
explanation for this may be the avoidance of alkaloids such as lolitrem
B, ergovaline and peramine that are produced at that time of the year by
endophytic fungi in ryegrass. We tested this hypothesis by exposing
groups of three sheep to three food items (ryegrass with wild-type
endophyte (E+), ryegrass with no endophyte (E-), and white clover (CL)),
in December and in February. Each food was offered singly and in pairs,
and time spent grazing on each food, short-term dry matter (DM) intake
rate, and preference was measured. In February, sheep given E+ or E-
ryegrass alone, grazed for 400 mins/day, compared with 370 mins/day when
given a choice between them (P=0.15, SEM=14). The time spent grazing on
the E+/E- choice was comprised of 280 mins/day on E- and 90 mins/day on
E+ indicating a strong preference for E-. When offered ryegrass and
white clover, the total grazing time (335 mins/day), and the grazing
time on clover (285 mins/day) and on ryegrass (50 mins/day), were
similar for E+/CL and E-/CL. Short-term dry matter intake rate of grass
(3.4 g DM/min), and the strong preference for clover in this study, were
unaffected by the presence of endophyte. We conclude that while sheep
detect endophyte alkaloids, they avoid eating them only when doing so
does not reduce daily intake or change the proportion of grass and
clover in their diet.
Keywords: NZSAPAB;
diet selection; sheep; perennial ryegrass; endophyte; alkaloids;
Neotyphodium lolii
Last Updated 30/07/2002
