Effects of condensed tannins on animal performance in lambs grazing
Yorkshire fog (Holcus lanatus) and annual ryegrass (Lolium multiflorum)
dominant swards
F. Montossi, J. Hodgson, S.T. Morris and D.F. Risso
Department of Plant Science, Massey University, Palmerston North,
New Zealand.
Proceedings of the New Zealand Society of Animal Production, 1996,
56: 118-121
A comparative study was undertaken in Uruguay from August to early
November 1994 to investigate differences in animal performance between
lambs rotationally grazing mixed swards of annual ryegrass (Lolium
multiflorum) and white clover (Trifolium repens) or Yorkshire fog (Holcus
lanatus) and Trifolium repens. The effects of condensed tannins (CT) on
lamb production were assessed by twice daily oral administration of
polyethylene glycol to half the lambs on each sward combination. Lambs
grazing on Yorkshire fog swards had higher clean wool growth (1470 vs
1280 ± 39 µg cm-2 day-1, P < 0.01), greater liveweight gains (152 vs 108 ±
5.5 g day-1, P < 0.001), final weight (42 vs 38 ± 0.5 kg, P < 0.001), and
carcass weight gains (89 vs 69 ± 2.5 g day-1, P < 0.001) than lambs grazing
annual ryegrass swards. Slightly higher condensed tannin (CT) dietary
concentrations were recorded in Yorkshire fog swards than in annual
ryegrass (0.420 vs 0.365 ± 0.021% on a DM basis, P < 0.08). These low CT
levels increased clean wool growth (1440 vs 1310 ± 32 µg cm-2 day-1, P <
0.05) and liveweight gains (141 vs 120 ± 4.3 g lamb-1 day-1, P < 0.01). The
effects of CT on animal performance were greater in Yorkshire fog swards.
The results of this experiment indicate (i) the advantage of Yorkshire fog
over annual ryegrass for lamb production under moderate to low soil fertility
conditions, and (ii) CT concentrations in forage diets close to 0.5% on DM
basis are the minimum needed to significantly improve ruminant production.
Keywords: NZSAPAB;
annual ryegrass (Lolium multiflorum); Yorkshire fog (Holcus lanatus);
white clover (Trifolium repens); birdsfoot trefoil (Lotus corniculatus);
polyethylene glycol (PEG); condensed tannins (CT); lamb growth; wool
growth.
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Last Updated 18-03-1997
