Anti-nutritive factors

Early reports concerning the role of Gliricidia as a forage refer to its toxicity and certainly the derivation of the generic name (glis = dormouse, caedo = kill) implies a toxicity to rodents. Furthermore, the powdered bark and seeds have been used as a rodent poison in the tropics and Skerman et al. (1988) confirmed that the roots were toxic to rodents and suggested that the leaves could poison horses.

Potentially toxic substances have been isolated from Gliricidia, including coumarins (Griffiths, 1962), hydrocyanic acid (Manidool, 1985), alkaloids (Glander, 1977), and tannins (Devendra, 1983). Furthermore, it is suspected that Gliricidia may be a nitrate accumulator responsible for a 'cattle fall syndrome' in Colombia (Tiheebilcock, 1978).

However, whilst toxic effects have been well documented in non-ruminants, conclusive evidence in ruminants is lacking. Recent work (Ash, 1989) reported moderate condensed tannin levels in Gliricidia (20.5 g/kg DM), and yet the plant material was more degraded in the rumen than that of other plants of a similar tannin content. Condensed tannins may differ in type and behaviour between plant species. It also appeared that tannins could be altered by feed treatment. Oven-drying, a process by which animal acceptance has been increased, resulted in an apparent loss of tannins (Ahn et al., 1989). Palatability could be improved by this process, although it could also have been modified by the destructive effect of heat on other plant components such as coumarins.

In conclusion, under practical feeding conditions, Gliricidia does not seem to be toxic to ruminants, although palatability may be a problem in some areas. It should be used with caution as a dietary supplement of diets for non-ruminants.