RELATIONSHIP BETWEEN CONDENSED TANNINS AND DRY MATTER DEGRADABILITY OF TWO TROPICAL FODDER LEGUMES

Abstract

In the tropics tree fodder legumes provide adequate protein to ruminants, particularly in the dryseason. However, many of them contain high levels of anti nutritional factors such as condensedtannins. Therefore, the objective the present study was to investigate the relationship betweencondensed tannin (CT) content and the in vitro dI) matter digestibility (DMD) of two tropicalshrubs, Gliricidta septum and Ca/liandra calothyrsus. The tannin binding chemical polyethyleneglycol (PEG) was added at rates of 0.1500 and 5000mg /lOOg plant substrate to asses the effectonDMD.

Although the PEG response was not marked, G. sepium had significantly (P<0.05) higher DMD(60%-65%) in all treatments as compared with C. calothyrsus. In contrast, DMD ef C.calothyrsus increased (39.5% to 53.5%) with the addition of PEG. Extractable CT levels rangedfrom 0.57% in G. septum to 4.05% in C. calothyrsus. Results indicate that C. calothyrsus in spiteof having a lower DMD due to high levels of condensed tannins, the addition of PEG had asignificantly higher and desirable effect on DMD compared to G. sepium.

The significant co-correlation of DMD and CT indicates that PEG binding technique is asuitable method to improve the dry matter degradability of tannin rich tropical forages.