Intra- and inter-specific variations in the effects of condensed tannins on ruminal fermentation
T.T. Tiemann
1,2, C.E. Lascano
2, M. Kreuzer
1and H.D. Hess
1,31ETH Zurich, Institute of Animal Science; 2Centro Internacional de Agricultura Tropical (CIAT);
3Agroscope Liebefeld-Posieux, Swiss Federal Research Station for Animal Production and Dairy Products (ALP)
Swiss Centre for International Agriculture Schweizerisches Zentrum für Internationale Landwirtschaft Centre Suisse pour l’Agriculture Internacional Swiss Centre for International Agriculture Schweizerisches Zentrum für Internationale Landwirtschaft Centre Suisse pour l’Agriculture Internacional
Trees for poverty alleviation ZIL Annual Conference June 9, 2006, ETH Zurich
Background
¾Condensed tannins, abundant in many tropical forage legume trees, may vary in their chemical characteristics depending on species, accession and cultivation site.
¾Different condensed tannins may affect ruminal fermentation in contrasting ways.
¾This experiment was conducted to assess the effect of extracted condensed tannins from three widely used shrub legume species on ruminal fermentation in vitro.
Materials and Methods
Experimental treatments
¾Basal substrate: mixture of a tropical grass (Brachiaria humidicola) and a tropical herbaceous non-tanniniferous legume (Vigna unguiculata; 2:1 on dry matter [DM] basis).
¾Incubated alone or with the addition of purified tannins.
¾Tannin levels: 25, 50, 75 and 100 mg/g dry matter.
Tannins
¾Tannins were extracted from:Leucaena leucocephala734, Flemingia macrophylla17403,Calliandra calothyrsus22310 and Calliandra calothyrsus22316.
In vitro technique
¾Gas pressure transducer technique.
¾Triplicate samples of test mixtures incubated for 144 h.
¾Solid fermentation residues analysed for DM and crude protein (CP) content and fermentation fluid for total volatile fatty acids and ammonium.
Tannins were extracted from leaves of different tropical shrub legumes.
Results
Conclusions
¾There exist differences in the effects of condensed tannins from different legume species on ruminal fermentation.
¾Tannins from Leucaena and Flemingia were less effective in decreasing ruminal fermentation than tannins from Calliandra.
¾Tannins of the two accessions of Calliandra differed in their effects, indicating that there exist within-species variation.
Apparent DM degradability (mg/g)
0 200 400 600 800 1000
Control 25 50 75 100 25 50 75 100 25 50 75 100 25 50 75 100 Tannin addition (mg/g DM)
Leucaena
Flemingia
Calliandra
22310 22316
Apparent CP degradability (mg/g CP supply)
0 100 200 300 400 500 600 700
Contr
ol 25 50 75 100 25 50 75 100 25 50 75 100 25 50 75 100
Tannin addition (mg/g DM) Leucaena
Flemingia
Calliandra
22310 22316
Total volatile fatty acids (mmol/l)
0 20 40 60 80 100
Control
25 50 75 100 25 50 75 100 25 50 75 100 25 50 75 100
Tannin addition (mg/g DM) Leucaena
Flemingia
Calliandra
22310 22316
Ammonium contentration (mmol/l)
0 2 4 6 8 10 12 14
Control 25 50 75 100 25 50 75 100 25 50 75 100 25 50 75 100 Tannin addition (mg/g DM)
Leucaena
Flemingia
Calliandra
22310 22316
