Effects of Mimosa Bark extract containing condensed tannins on
rumen metabolism in sheep and milk production by grazing cows.
Mashudi, I.M. Brookes, C.W. Holmes and G.F. Wilson
Department of Animal Science, Massey University, Private Bag
11222, Palmerston North.
Proceedings of the New Zealand Society of Animal Production. 1997,
57: 126-129
A Mimosa Bark extract (MB) was given to sheep and cattle to
provide condensed tannins (CT) at levels which increased growth in
lambs. The effects on rumen metabolism in sheep and milk production in
grazing cows were studied in two experiments during spring 1994. MB
contained 507g CT/kg bark and was administered as a water suspension
(280g/litre). In Experiment 1, six rumen fistulated wethers were offered
fresh pasture for two periods of 10 and 14 days, during which each sheep
was drenched twice daily with 12.5 ml of either water or MB suspension
(4.1 g CT/kg pasture DM intake), in a cross-over design. MB did not
significantly affect DM intake, in sacco DM disappearance or
apparent digestibility of DM or nitrogen (N), but ruminal ammonia-N and
plasma urea concentrations were significantly decreased (P<0.05). In
Experiment 2, 30 Friesian cows grazing mixed pasture were allocated to
one of three treatments: undrenched control (C) or twice daily drenching
with 90 (L) or 180 (H) ml of MB suspension (1.8 or 3.6 g CT/kg pasture
DM intake) for three weeks. No significant differences in yields of milk
or milk constituents were observed. Live weight and condition score
changes did not differ significantly. Plasma urea concentrations were
significantly lower (P<0.05) in treatment H than in treatment C.
These results indicate that drenching with MB, at daily rates of 4 g
CT/kg pasture DM intake, reduced ruminal protein degradation in sheep
and cattle, but did not increase milk production.
Keywords: NZSAPAB;
Condensed tannins; mimosa bark; pasture; dairy cows; protein
digestion; milk yield; rumen ammonia; plasma urea.
Last Updated 12-09-1998
