New Zealand Journal of Agricultural Research abstracts
Comparative studies of herbage intake and performance of lambs grazing
Yorkshire fog (Holcus lanatus) and tall fescue (Festuca
arundinacea) pastures under rotational management in summer
F. Y. LIU
J. HODGSON*
Department of Plant Science
Massey University
Palmerston North, New Zealand
T. N. BARRY
Department of Animal Science
Massey University
Palmerston North, New Zealand
Abstract Grazing experiments were conducted on Yorkshire fog
(Holcus lanatus cv. Massey Basyn)/white clover (Trifolium repens
cv. Grasslands Tahora) and tall fescue (Festuca arundinacea cv.
Grasslands Roa)/white clover pastures in late spring-summer (Nov-Jan,
Experiment 1) and summer-early autumn (Jan-Mar, Experiment 2) to assess
behaviour and performance of lambs and to evaluate the effects of low
concentrations of condensed tannins (CT) in the grasses on lamb performance.
In each experiment, 48 lambs were allocated to three groups, balanced for
previous grazing experience and sex, in sets of 16. One group was slaughtered
at the start of the experiment to measure carcass weight; the other two groups
of lambs rotationally grazed paddocks within each pasture. Half of the lambs
within each pasture were drenched with 10 g polyethylene glycol (PEG; mol.
weight 3350) twice daily at 0830 and 1630 hrs and the remaining lambs were
drenched with water as a control.
There were similar sward surface height, herbage mass, and bulk density on
both swards. Yorkshire fog had a higher proportion of sown grass and lower
proportions of other grasses and white clover than tall fescue. There was
slightly higher total N (3.37 vs 3.30 +/- 0.013%, P < 0.05) on tall
fescue than on Yorkshire fog in summer, but no significant difference in
organic matter digestibility (OMD) for the diets from the two pastures. The
diet from Yorkshire fog had higher CT concentrations overall.
Herbage organic matter (OM) intake was not significantly different between the
two pastures overall, but was significantly reduced by PEG administration in
Experiment 2 (P < 0.01). Previous grazing experience had no
significant effects on lamb performance. Lambs had greater carcass weight (14.7
vs 13.9 +/- 0.2 kg, P < 0.05) and faster carcass weight gain (32 vs
20 +/- 3.1 g/day, P < 0.05) on Yorkshire fog than on tall fescue in
Experiment 1, but not in Experiment 2, and faster rate of clean wool growth on
Yorkshire fog than tall fescue in Experiment 2 (123 vs 112 +/- 2.8 mg/100
cm2 per day, P < 0.05).
It is concluded that Yorkshire fog cv. Massey Basyn offers potentially greater
nutrient intake and weaned lamb performance than tall fescue cv. Grasslands Roa
in summer pastures. The limited content of condensed tannins in the Yorkshire
fog pasture had no measurable effects on lamb performance, and it is suggested
that particularly low concentrations of CT measured in tall fescue may have
been an artefact of the analytical process.
Keywords animal performance; condensed tannins (CT); diet
selection; grazing behaviour; herbage intake; polyethylene glycol (PEG); tall
fescue (Festuca arundinacea); white clover (Trifolium repens);
Yorkshire fog (Holcus lanatus)
New Zealand Journal of Agricultural Research, 1997, Vol. 40: 475-487
0028-8233/97/4004-0475 $7.00/0 (c) The Royal Society of New Zealand
1997
PDF file of entire paper: medium quality (1172K); (scanned from paper original: notes about this process)
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