The effects of condensed tannin in Lotus corniculatus upon nutrient
metabolism and upon body and wool growth in grazing sheep.
Y. Wang, G.C. Waghorn, G.B. Douglas, T.N. Barry, G.F. Wilson.
Department of Animal Science, Massey University, Palmerston North,
New Zealand.
Proceedings of the New Zealand Society of Animal Production 1994,
54: 219-222
Lotus corniculatus containing 23 g/kg DM of extractable condensed
tannin (CT) and 35 g total CT/kg DM was fed to sheep in two experiments. In
both experiments half the sheep received supplementation with polyethylene
glycol (PEG), which binds and inactivates CT, enabling the effects of CT to be
quantified by comparing control sheep (CT operating) with PEG sheep (CT
inactivated). Experiment 1 was conducted indoors, with sheep held in
metabolism crates and fed hourly to determine the effects of CT upon apparent
digestibility and upon plasma irreversible loss (IRL) rates of methionine,
cystine and inorganic sulphate, using 35S labelling. Experiment 2 as a field
trial with weaned lambs given a restricted allowance of either lotus
corniculatus (CT-containing) or lucerne (non CT-containing), with or without
PEG supplementation. In Experiment 1, CT slightly lowered the apparent
digestibility of organic matter (0.77 vs 0.80; P<0.1), hemicellulose (0.61 vs
0.67; P=0.118) and markedly reduced nitrogen apparent digestibility (0.72 vs
0.80; P<0.01), but had no effect upon cellulose digestibility. CT increased the
IRL of plasma cystine (13.1 vs 7.0 mmol/min; P<0.05) and reduced the IRL of
plasma inorganic sulphate (36.8 vs 48.1 mmol/min; P<0.01) but had no effect
upon plasma methionine IRL. In Experiment 2, live weight gain and wool
growth were similar for sheep grazing lucerne (with and without PEG
supplementation) and for sheep grazing lotus with PEG supplementation. In
sheep grazing lotus, action of CT increased wool production (12.1 vs 10.9 g/d;
P<0.05) and slightly increased live weight gain (203 vs 188 g/d; P=0.07).
These experiments showed that CT in Lotus corniculatus increased the
amount of cystine available for body synthetic reactions and increased wool
growth.
Keywords: NZSAPAB;
condensed tannin; sulphur amino acids; sheep; digestibility & wool
growth.
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Last Updated 25-01-1997
