Abstract
In vitro and in vivo experiments were carried out to evaluate the nutritive value of three tropical browse species as assessed by DM and CP digestibility, and NDF and ADF degradability with incubation times (T) of 6, 12, 24 and 48h. During the in vivo digestibility experiment three male castrated sheep (age 16 - 25 months) with a mean liveweight of $11.5{\pm}0.9kg$ were placed in individual metabolism stalls and were allocated to one of the three browse species in a $3{\times}3$ Latin square design. The browse species were all leguminous and consisted of: Acacia sieberina (A. sieberina), Ficus polita (F. polita), and Ficus sycomorus (F. sycomorus). The mean DM and CP contents of F. polita were higher than for A. sieberina and F. sycomorus (p<0.05). In contrast the NDF and ADF contents of F. sycomorus were higher compared to the other species examined (p<0.05). The in vitro DM and CP digestibility, and NDF and ADF degradability observed at different stages of incubation were higher in F. polita followed by A. sieberina and F. sycomorus. The DM and CP digestibility at 48 h incubation were 72.92, 74.84 and 53.52% and 77.38, 77.68 and 63.64% for A. seiberina, F. polita and F. sycomorus, respectively. This shows that F. polita contains more soluble materials which ruminant can benefit from and hence has more feeding value. The fermentation of F. sycomorus was slower for all the nutrients evaluated due to the presence of more fibre. Similarly, higher in vivo digestibility coefficient of DM, CP, NDF, ADF and hemicellulose were observed for F. polita reflecting its higher values of CP, ether extract (EE) and hemicellulose associated with lower values of NDF and ADF. Higher DMI and daily gain were recorded in sheep during feeding of F. polita compared to the other species evaluated. The digestibility of all the nutrients examined were higher in the in vivo than in the in vitro trial except for CP and DM. Sheep showed no visual signs of toxicity throughout the study periods. These results showed A. seiberina, F. polita and F. sycomorus can sustain sheep on a maintenance diet and could as well be used as a supplementary feed to low producing animals during the tropical dry season. Further research is needed to ascertain the viability of using these browse species on a long-term basis.