TANNINS IN SOME AGRO FORESTRY SPECIES OF LOCAL INTEREST

Abstract

Total and condensed tannin contents were determined in six agro forestry species usedby local farmers to feed ruminants. Total and condensed tannins were determined byFolin-Ciocalteu and Butanol-Hcl methods respectively. Total tannin (1T) contentranged from 5.41% for Calliandra calothyrsus to 0.15% for Erythrina indica.Condensed tannins (CT) contents ranged from 6.92% in Acacia auricu/iformis to 0.78%in G/iricidia sepium. The percentages of CT were 6.40%, 4.60%, and 1.58% respectivelyfor Artocarpus heterophy//us, C. ca/othyrsus, and Leucaena le ucoceph ala. Among thesix species tested, E. indica, was free of CT while having traces of IT. On the basis oftheir respective CT contents G. sepium was classified as containing traces of CT «1 %),while L. /eucocepha/a classified as containing low level of CT (1-3%). C. calothyrsuswas classified as containing medium level of CT (4-6%) while A. auriculiformis and A.heterophyl/us classified as containing high level of CT (>6%).

In a further study, it was found that tender leaves and stems (0-30 cm from the tip) of C.calothyrsus, and A. auriculiformis contained higher levels of IT and CT as comparedwith mature leaves and stems (30-60 em from the tip) of the same species. In contrasttender leaves and stems of A heterophyllus contained low levels IT as compared withmature leaves and stems.

The results suggest that IT and CT contents of tested six species are different due totheir inherent characteristics. It was also evident that tannins are present not only inleguminous species but also in non-leguminous species such as A. heterophyllus. Theincrease in TT and CT contents in tender parts of C. callothyrsus and A. auriculiformismay be associated with the chemical defence mechanisms found in younger plant parts.Further investigations are necessary to verify the effects of tannins on their nutritivevalue of above forages