General considerations
Lebbek leaves, flowers and pods are all valuable feeds for ruminants. They are particularly interesting in extensive grazing systems, as they drop sequentially during the dry season (in comparable amounts for mature trees) and are eaten directly by grazing animals without requiring management (Lowry, 1989). They are recommended to supplement ruminant diets when forage matures or when dry seasons occur. In agro-pastoral systems, lebbek trees may be cultivated in rows or woodlots and provide protein supplement or feed for times of scarcity (Lowry et al., 1998). In India, lebbek is one of the preferred forage tree for cows, buffalo and draught animals (Maharaj Singh et al., 2002).
Lebbek forage enhances digestible dry matter intake of low quality diets. The lower quality of the basal diet, the higher the enhancement due to lebbek (Lowry et al., 1998). Lebbek also increased nutrient digestibility and utilization in pregnant ewes fed on a Cenchrus ciliaris based diet (Pailan et al., 2003).
Lebbek forage can be fed as hay or silage, alone or mixed with grasses. Foliage mixed with grass makes a good quality silage for lactating goats (Soca et al., 1999; Solorio-Sanchez et al., 2007).
The lebbek tree has also a very positive side-effect: because of the high quality shade it provides (light transmission reduced by 60%), animal heat stress is decreased and milk yield is enhanced (+ 0.9 litres milk/cow/day) (Sanchez et al., 1999; Lowry et al., 1998).
Leaves
Lebbek leaves can have a protein content as high as 23% DM when young, but protein content in leaf litter is about 10%. Cell wall content (as NDF% DM) increased with maturity but remained relatively high, between 40 and 50% (Prinsen, 1986). Being short-lived, lebbek leaves have a low lignin content and compare favourably with other legume tree leaves. They are remarkably free of toxic compounds and tannins and have very low levels of soluble phenolics and other secondary metabolites (Rai et al., 2007; Garcia et al., 2005; Garcia et al., 2006a; Bhatta et al., 2005).
Reported in vitro and in vivo digestibility values are in the 45-70% range, mature leaves being about 50% digestible. Leaf digestibility is highest early in the season, or in regrowth after cutting, but is only moderate for mature leaves, although still of higher quality than mature grass. ME value ranges between 7.5 and 9.0 MJ/kg DM. In sheep, DMI for lebbek leaves ranges from 55 to almost 100 g DMI/kg LW0.75. Fallen leaves seem to be more appreciated than dry green leaves (84.0 vs. 61.5 DMI/kg LW0.75, Lowry, 1989). Young leaves taste bitter: intake may be limited when offered as the whole diet, but this does not affect their value as a supplement (Lowry et al., 1998).
Lebbek leaves can be included in roughage-based diets to improve the protein nutrition status of ruminants (Raghuvansi et al., 2007; Amanullah et al., 2006). Fallen leaves have considerable feed value as a supplement to dry season grass. This may be due to both its N content and a low molecular weight constituent, as well as the differing morphology and chemistry of the lignocellulose substrates between lebbek leaves and grass (Kennedy et al., 2002). Leaves can be fed to goats as the sole roughage during periods of feed scarcity (Bais et al., 2002)
Lebbek leaves can replace cottonseed cake as a protein supplement for goats (Ndemanisho et al., 2006). They are better than wheat bran in improving the utilization of ammonia-treated bagasse in smallholder owned goats during the dry season (Balgees et al., 2009).
Flowers
Fallen flowers are relished by sheep and considered as an excellent feed (Cook et al., 2005; Lowry et al., 1998).
Pods
Immature pods are accepted readily by livestock but mature pods are not palatable (FAO, 2010). While pods fed alone give a poor animal response, the response becomes very positive when they are used to supplement poor quality grass. Pods can be used both as a moderate protein source (protein content is about 20% DM) and as an energy source (Ram Ratan et al., 2005).
Dried pod meal can supplement lactating dairy cows diet up to 50-85% of the supplement (Lamela et al., 1998).
