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

Calliandra leaves, green pods, and seeds were harvested from the central hi ghlands 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-ol d plants were further separated into top 30 cm, lower 30 cm and mixed leave s. Dry matter (DM), ash, nitrogen, neutral detergent fibre (NDF), acid dete rgent 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 consecu tive batch culture (CBC) system. Calliandra leaves and seeds were rich in c rude protein (CP) and had a balanced amino acid profile. The pods had highe r NDF and ADF contents than the leaves or seeds, and the older leaves had h igher calcium content than young leaves. The leaves contained high concentr ations of flavanols and PAs whereas the seeds appeared not to have any dete ctable flavanols. The in situ rumen DM degradability of leaves was surprisi ngly high. The mean DM degradation asymptote (A+B) for all of the leaves wa s 781 g/kg. The pods were however less degradable in the rumen than the lea ves. Except for the mixed leaves with a rather low average CP degradation o f 358 g/kg CP after 48 h of incubation, the CP degradation after 48 h of in cubation of the other leaves was relatively high. The average CP degradatio n for the other leaf fractions was 525 g/kg CP. In contrast to the DM and C P 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 increas ed. The DM degradation of the seeds in vitro was higher (P < 0.05) than tho se of the other plant parts. The 4 month-old leaves appeared to be the leas t 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. (C) 1999 Elsevier Science B.V. All r ights reserved.