New Zealand Journal of Agricultural Research abstracts
Perennial ryegrass endophyte effects on plasma prolactin concentration
in dairy cows
S. J. Bluett
E. S. Kolver
M. J. Auldist
E. R. Thom
Dexcel
Private Bag 3221
Hamilton,
New Zealand
S. R. Davis
V. C. Farr
Ruakura Research Centre
Private Bag 3123
Hamilton,
New Zealand
B. A. Tapper
AgResearch
Grasslands Research Centre
Private Bag 11 008
Palmerston North,
New Zealand
Abstract The aim of the two experiments reported here
was to determine whether cows grazing perennial ryegrass infected with wild
endophyte (Neotyphodium lolii) had reduced plasma prolactin concentrations
compared with cows consuming a diet containing zero or low levels of ergovaline.
The seasonal profile of plasma prolactin concentration was determined in
27 dairy cows grazing perennial ryegrass infected with wild endophyte, and
in 28 cows fed a total mixed ration (TMR) diet in the 1999/2000 season. The
concentration of prolactin in blood plasma from cows fed TMR was generally
higher than the pasture-fed cows from November to April (20.6 versus 16.9
ng ml-1, standard error of difference (SED) = 1.13), but the magnitude
of the difference changed over time. Peak ergovaline levels of 0.8 mg kg-1
were recorded in ryegrass pasture in mid March 2000. In a second experiment,
18 cows grazing perennial ryegrass infected with the novel endophyte AR1
(no ergovaline or lolitrem B production) had higher concentrations of prolactin
in February 2001 than 18 cows grazing ryegrass infected with wild endophyte
(25.2 versus 14.4 ng ml-1, SED = 2.66), although concentrations
were similar during January 2001. Prolactin concentration does not provide
a reliable indicator of endophyte effects in dairy cows.
Keywords ergovaline; Lolium perenne; milk yield;
Neotyphodium lolii
A02012 Received 18 February 2002: accepted 5 November 2002; published
26 March 2003
New Zealand Journal of Agricultural Research, 2003, Vol. 46: 9-14
0028-8233/03/4601-0009 $7.00/0 © The Royal Society of New Zealand
2003
PDF file of entire paper (subscribers only): Print-quality (83K) |
screen-quality (66K)
This year's abstracts |
Journal home page |
All abstracts |
Publishing home page
