A joint project with:
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
The financial support of the Swiss Centre for International Agriculture (ZIL) is gratefully acknowledged.
Effects of different purified condensed tannins from tropical shrub legume species on ruminal fermentation in vitro
H.D. Hess
1,2, T.T. Tiemann
2,3, C.E. Lascano
3and M. Kreuzer
21Agroscope Liebefeld-Posieux, Swiss Federal Research Station for Animal Production and Dairy Products (ALP); 2Institute of Animal Science, ETH-Zurich; 3Centro Internacional de Agricultura Tropical (CIAT), Cali, Colombia
Background
¾Many tropical shrub legumes contain condensed tannins.
¾Condensed tannins 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 unguigulata; 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 C. calothyrsus22316.
¾Extraction was performed with an aqueous solution of acetone (700 ml/l), formic acid (5 ml/l) and ascorbic acid (5 g/l).
¾Tannins were purified on a Sephadex LH-20 gel column.
In vitro technique
¾Gas 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.
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 nutrient degradation than both Calliandra accessions.
¾Condensed tannins of the two accessions of Calliandra differed in their effects, indicating that there exist within-species variation.
Results
Tannins were extracted from leaves of different tropical shrub legumes.
In vitro assessment of ruminal fermentation using the gas transducer technique.
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
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
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
