Abstract:
The aim of the study was to evaluate the chemical composition, rumen degradability and in-vitro ileal digestibility of dry matter (DM) and nitrogen (N) in Ficus polita and Ficus benjamina leaves for optimum utilisation as supplementary protein sources for ruminant livestock. Leaves from Ficus polita and Ficus benjamina were harvested in late summer and in winter from one site within Tshakhuma, Limpopo province, South Africa. Five trees from each species were selected as they randomly occurred along an approximately linear transect of 1 km extending from west to east direction. The leaves were air-dried, milled through a 1 mm screen and analyzed for dry matter (DM), ash, N, neutral detergent fibre (NDF), acid detergent lignin (ADL), acid detergent fibre (ADF) and acid detergent insoluble Nitrogen (ADIN). The DM and N degradability were estimated using approximately 5 g leaf samples which were milled through a 1 mm screen and incubated in duplicate in nylon bags (external dimension: 6 × 12 cm, pore size of 46 μm) inside the rumen of three cannulated Bonsmara steers for 0, 4, 8,16, 24, 48, 72 and 96 hour periods. Parameters to describe the dynamics of ruminal degradability of DM and CP were obtained by fitting the data on the exponential equation P = a + b (1 - e-ct) using the NEWAY computer program, where “p” is the DM and CP disappearance at time t, (potential degradation), “a” is the rapidly degradable fraction, “b” is the slowly degradable fraction, “c” is the degradability rate of the “b” fraction and “t” is the degradation time. Post-ruminal in vitro DM and CP digestibility of the rumen undegradable residues were determined by the pepsin-pancreatin (gastric-small intestinal) digestion procedure. Data was subjected to analysis of variance in a 2 (season) x 2 (species) factorial treatment layout. Interaction between the season and species was significant (P<0.01) for Ash, CP, ADF, ADL with the ADF and ADL significantly higher (P<0.01) in winter compared to harvested F. polita leaves. For DM, there was a significantly difference for “b” and for the ED at all outflow rates (P<0.01) in both species, and for “a+b” (P<0.05). The insoluble degradable DM fraction ‘b’ were higher in F. polita than in F. benjamina in both dry and wet seasons. The CP disappearance components ‘a’ and ‘b’ differed significantly (P < 0.01) among the two species. Ficus polita leaves had significantly higher CP digestibility at 24-hr and 48-hr than F. benjamina leaves at 24- and 48-h of rumen incubation in both harvest seasons. It can be concluded that species and season affected the chemical composition, in-situ degradability of DM and CP, and in vitro post ruminal digestibility of the Ficus browse species, with the degradable DM and CP for both species adequate to serve as protein supplements to low-quality ruminant feeds.
