Variation in the nutritional value of leaf and stem fractions of nineteen leucaena lines

In two experiments, 2.5-month-old edible regrowth of the genus Leucaena (varying in tolerance to the leucaena psyllid pest attack) were analysed for nutritive value. In Experiment 1, forage of nine lines was separated into young leaves, young stems (within woody fraction <5 mm diameter), old leaves and old stems (within a woody fraction 5–10 mm diameter) whereas in Experiment 2, forage of the other 10 lines was separated in main stem leaves, branch leaves, young branches, young main stems, old main stems and old branches for analysis. Major differences were recorded between lines and forage fractions. Nutrient contents in dry matter were: nitrogen 0.7–4.8%, phosphorus 0.1–0.3%, potassium 0.2–2.5%, calcium 0.2–1.6%, magnesium 0.1–0.6%, acid detergent fibre 20–63%, lignin 8–23% and in vitro dry matter digestibility 15–69%. The leaves and immature fractions were higher in nitrogen, phosphorus, potassium and digestibility but lower in calcium, magnesium and fibre. Nutrient content in L. Leucocephala lines exceeded that in L. esculenta, L. diversifolia, leucaena hybrids and the composites. Based on the data, a management strategy that will promote young growth is suggested as appropriate for high quality forage production.