Fodder characteristics

The foliage of Gliricidia has been more or less accepted throughout the tropics as a source of high quality fodder. This is despite some traditional beliefs that the plant is toxic at the flowering stage, particularly to non-ruminants (Carew, 1983). Seeds or powdered bark are mixed with rice for use as a poison for rats and mice (Uphof, 1968), while the leaves are reputedly toxic to dogs and horses but not to cows and goats (Blohm, 1962). Some non-ruminants, however, are able to tolerate it, at least at low levels of intake, since it has been successfully used in Venezuela as a replacement for Medicago sativa (lucerne, alfalfa), as a yolk colourant in maize-based diets for laying hens (Ford, 1987). Levels of 2-4% of Gliricidia leaf meal are recommended for poultry diets (NFTA, 1989). As a supplement for fish, Gliricidia meal has compared favourably with other leguminous fodders (Raj and Kutty, 1984).

Reports vary on the toxicity of G. sepium. The flowers and leaves are eaten by humans where it grows but they may be detoxified by the cooking process (Martin and Ruberte, 1975). It was claimed by Neal (1948) that plants grown in Hawaii were not poisonous. Despite the conflicting reports, it has been successfully used for feeding ruminant livestock in many tropical countries of the world.

As a browse plant, the shoots and sprouts, especially the tender twigs, together with the fruits, pods and stems, are cropped by domestic and wild animals. Fodder is also cut at varying intervals and carried to provide a high protein supplement to small and large ruminants. Its use in alley cropping is widely reported (ILCA, 1988). The trees can withstand grazing and lopping and can be trimmed to a height of 1-1.5 m to serve as living fence posts and to provide limited forage within reach of browsing animals.

Data concerning browse productivity are few and variable and must be viewed with caution, since the age, species and size of the trees as well as the prevailing agro-climatic conditions can have considerable influences on foliage yields. ILCA (1988) cited a yield of 4475 kg/ha leaf dry matter (DM) over a 19-month period, equivalent to an annual DM yield of around 2800 kg/ha for the humid region of Nigeria,. In a similar area, a three-year old crop of Gliricidia yielded 1131-2703 kg/ha DM over a five month period, equivalent to annual DM production of 2700 to 6500 kg/ha. Management practices will also have an effect on yield (see page 8).

Data on the variation in yield with season are even scarcer and presumably more variable than those for annual production. Oakes and Skov (1962) reported monthly yields of 990 kg/ha for Gliricidia in the dry season, compared with 1480 kg/ha in the wet season. During times of stress, Gliricidia will shed its leaves, a characteristic which detracts from its usefulness as a standing reserve of high quality fodder to be carried over for feeding as a dry season supplement for lower quality roughages.

The yield of fresh forage of the whole tree is closely related to the fresh weight of a single branch in both Gliricidia and Leucaena. This gives a rapid, largely non-destructive method for estimating forage yields of intensively managed plantations (Sumberg, 1984).

Typical data for proximate and fibre analyses of G. sepium are shown in Table 1. In general, they indicate good feeding value. NFTA (1989) confirmed this conclusion, suggesting that the foliage contained high levels of crude protein and calcium but low levels of phosphorus. Amino acid profiles (Chadhokar, 1982) compared favourably with herbaceous legumes such as Medicago sativa.

In a review, Smith and van Houert (1987) concluded that, in common with many legumes, G. sepium contained sufficiently high levels of most minerals (except phosphorus and copper) to meet tropical requirements and it would make an excellent feed during the dry season, when protein and mineral deficiencies commonly occur. These comments apply equally to fresh foliage or to material conserved as dried leaf meal. Numerous reports consider the benefits of Gliricidia in terms of animal production, often as a supplement to poor quality diets (Ash, 1989). The foliage is highly degradable in the rumen (Minor and Hovell, 1979) and it is well digested (Wiersum and Dirdjo-soemarto, 1987). Although rarely offered as a sole feed, Gliricidia should serve to increase the digestibility of the diet when used to supplement low quality feeds (NFTA, 1989).

Table 1 Proximate and fibre analyses of leaves and bark of Gliricidia sepium

Notes: NFE - nitrogen free extract; DMD - dry matter digestibility; NDF - neutral detergent fibre; ADF - acid detergent fibre.
Sources: Chadhoker (1982); Falvey (1982); Devendra (1983); Nochebuena and O'Donovan (1986); and NFTA (1989).

Despite numerous reports to the contrary (e.g. NFTA, 1989), Smith and van Houtert (1987), reviewed performance trials with both small and large ruminants, and concluded that while the feeding of Gliricidia had no adverse effect on growth and reproductive performance, supplementation did not improve intake of the basal diet. When readily consumed, the bulky Gliricidia quickly distended the rumen, cutting down on the intake of the basal ration. In contrast to this, Ash (1989) considered that feeding small quantities of Gliricidia leaf to goats would significantly increase total DM intake when compared with mature tropical grass offered as a sole feed. Similarly, Chadhokar and Katharaju (1980) and Chadhokar and Lecumwasam (1982) reported increased levels of total intake when Gliricidia supplemented diets for dairy cattle and sheep respectively. These contrasting observations may be due, at least in part, to differences between species, or even between provenances, since little work has been done to characterize and stabilize varieties of Gliricidia.

Crushed Gliricidia leaves have been associated with a strong odour and this has resulted in palatability being described as only satisfactory to sheep (Nochebuena and O'Donovan, 1986) and unpalatable to rabbits (Raharjo and Cheeke, 1985). However, Chadhokar and Lecamwasam (1982) described Gliricidia as both acceptable and palatable to dairy cattle. While differences between provenances may explain some of the variability in reported animal acceptance, wilting for 24 hours between cutting and feeding appears to improve intake by reducing the odour of the foliage. The same effect can be achieved by oven drying. It has been reported that animals which initially refused Gliricidia became accustomed to it in a few days, after which it was readily consumed. The presence of animals used to eating the foliage accelerated acceptance by others which were being introduced to it (Atta-Krah and Sumberg, 1987).

The rather conflicting data suggest that Gliricidia can be a useful supplement to low quality roughage diets, even if the improvement in animal performance is not great.