Composition and degradability of different fractions of Calliandra leaves, pods and seeds

Abstract

Calliandra leaves, green pods, and seeds were harvested from the central highlands of Kenya. The leaves were collected from coppice shoots and plants of various ages (4 months, 1.5 and 2.5 years). Samples from the 2.5 year-old plants were further separated into top 30 cm, lower 30 cm and mixed leaves. Dry matter (DM), ash, nitrogen, neutral detergent fibre (NDF), acid detergent fibre (ADF), minerals, amino acids, flavanols and proanthocyanidins (PAs) were determined. Rumen degradability was measured in situ in sheep and in vitro degradability was measured with mixed rumen microbes in a consecutive batch culture (CBC) system. Calliandra leaves and seeds were rich in crude protein (CP) and had a balanced amino acid profile. The pods had higher NDF and ADF contents than the leaves or seeds, and the older leaves had higher calcium content than young leaves. The leaves contained high concentrations of flavanols and PAs whereas the seeds appeared not to have any detectable flavanols. The in situ rumen DM degradability of leaves was surprisingly high. The mean DM degradation asymptote ( A+ B) for all of the leaves was 781 g/kg. The pods were however less degradable in the rumen than the leaves. Except for the mixed leaves with a rather low average CP degradation of 358 g/kg CP after 48 h of incubation, the CP degradation after 48 h of incubation of the other leaves was relatively high. The average CP degradation for the other leaf fractions was 525 g/kg CP. In contrast to the DM and CP degradation in the rumen, NDF in the leaves increased as a proportion of the DM. However, the NDF gain was lower as the period of incubation increased. The DM degradation of the seeds in vitro was higher ( P < 0.05) than those of the other plant parts. The 4 month-old leaves appeared to be the least degradable among the leaves in vitro. The results showed that Calliandra leaves and seeds harvested from Kenya may have potential as dry season feed and protein supplement for ruminants.