Tannin content of selected fodder legumes

Fodder tree/ shrub legumes such as Leucaena leucocephala, Gliricidia sepium, Samanea saman, Sesbania sesban, Flemingia macrophylla, and Desmanthus virgatus are popular supplementary feeds to low ruminant diets. These fodder legumes are used as alternatives to expensive concentrates to improve animal productivity. However, most fodder legumes contain secondary compounds (e.g.,tannin) which are toxic when fed ad libitum and have negative effect on feed intake and digestibility. Thus, Orden et al. (CLSU) determined the tannin content of some selected fodder legumes so that appropriate fodder-based feeding strategies for goats will be developed. Eleven legumes species (Arachis pintoi, Centrosema pubescens, Desmodium cinorea, Desmathus virgatus, Flemingia macrophylla, Gliricidia sepium, Indigofera anil, L.leucocephala, S. saman, Sesbania grandiflora, and S. sesban) grown at the Small Ruminant Center- Central Luzon State University (SRC-CLSU) were used in the study. The evaluation was conducted in 2005. Findings of the study showed the following: The total extractable phenolics (TEPH) of the test legumes species ranged from 1.71% DM (Centro) to 12.28% DM (Flemingia), while total extractable tannin (TET) ranged from 0.16% DM (Indigo) to 8.27% DM (Flemingia). More than 65% of the extractable phenolic compounds in Flemingia and Leucaena were accounted as TET which could be a potential factor to affect nitrogen degradation in the rumen and possibly protein availability in the lower gut. Among the 11 legumes species analyzed, only Flemingia and Leucaena had complete condensed tannin fraction. Flemingia had the highest total condensed tannin (TCT) contents (4699ug/g DM) followed by Leucaena (2,826 ug/g DM), arachis (1,817 ug/g DM) Desmanthus (1,117 ug/g DM), and Sentro (33 ug/g DM). Results showed that Flemingia and Leucaena had higher polyphenolic compounds in the forms, of TEPH, TET, and TCT than the other test legumes. Since tannin has been shown to have anthelmintic property, Flemingia and Leucaena may be good and cheap sources of anthelmintics to reduce gastrointestinal parasite infestation. Hence, it is recommended that the direct effect of polyphenolic compounds in reducing internal parasite of goats be fully determined.