The interest in production of fuel ethanol from lignocellulosic materials is continuouslyincreasing due to the urgency of finding non-food substrates for production of bio-fuels.Marabou (Dichrostachys cinerea) is one of the abundant lignocellulosic bio-resources in Cuba,and it could be useful to produce bio-ethanol. Pre-treatment is an important step to produceethanol from lignocellulosic materials since it allows the separation of cellulose, hemicelluloseand lignin, and activates cellulose towards enzymatic hydrolysis. During the past few years,organosolv methods have been reported for effective separation of the main components oflignocellulosic materials and improvement of the enzymatic hydrolysis of cellulose. By usingacetosolv method lignin is separated under mild conditions and many of the lignin properties arewell preserved.The present work was aimed to perform a chemical characterisation of marabou biomass and toevaluate acetosolv delignification of the material. In this work the content of moisture, ash,extractives, easy-to-hydrolyze polysaccharides, difficult-to-hydrolyze polysaccharides, andKlason lignin of marabou biomass were analyzed. Klason lignin of the marabou biomass was23.4% of the mass. Acetosolv delignification was performed at normal boiling temperature(NBT) and 121oC, using 50-50, 70-30 and 90-10 acetic acid – water mixtures with 10% of solidsload during 1h. Hydrochloric acid (0.2g / 100g of mixture) was used as catalyst. Thedelignification of marabou biomass was also evaluated for the combination of dilute acid prehydrolysis(DAPH) and acetosolv with the same reaction conditions. This investigation provedthat acetosolv pretreatment was effective for solubilizing lignin contained in marabou biomass.The degree of lignin solubilisation increased with increasing acetic acid concentration in thereaction mixture. Lignin removals above 80% were achieved consistently both at NBT and121oC with 90% acetic acid, while only around 44.6 and 6.8% of the initial lignin was removedusing, respectively, 70 and 50% acetic acid at 121oC. The effect of temperature ondelignification was only marginal when acetosolv was conducted with 90% acetic acid, but itwas remarkable for lower acetic acid concentrations. A two-fold decrease of lignin removal wasobserved for the NBT acetosolv compared with the process performed at 121oC using both 70and 50% acetic acid. The insertion of a DAPH step prior to acetosolv considerably improvedlignin removal using 70 and 50% acetic acid at both temperatures, but its effect on the processesusing 90% acetic acid was minimal. High lignin yields were achieved upon its precipitation fromacetosolv liquors.

MSCAGR (Animal Science) / Department of Animal Science / Forage and browse legumes play an important role in sustaining livestock in small holder farming systems in the tropics, mainly as a result of their contribution to economic and environmental sustainability of livestock production. The study was conducted to determine the chemical composition, ruminal degradability and in vitro digestibility of dry matter (DM) and crude protein (CP) of Dichrostachys cinerea and Bauhinia thonningii leaves. The browse tree leaves were harvested in the wild in Shayandima, Limpopo province. The leaves were collected, oven-dried, milled to pass through a 1.0 mm sieve and analysed for chemical composition in the Animal Science Nutrition Laboratory, at the University of Venda. The browse tree leaves were analysed for DM nitrogen, neutral detergent fibre (NDF) and acid detergent fibre (ADF). Approximately 5 g of leaf sample milled to pass through through a 1 mm sieve were placed in nylon bags (external dimension: 6 × 12 cm, pore size of 41 μm) and incubated in duplicates for 0, 4, 8, 16, 24, 48, 72, 96 and 120 hours periods in the rumen of three cannulated Bonsmara steers. The residues were then analysed for DM and nitrogen. 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 NEWAY computer program, where “a” is the rapid degradable fraction, “b” is the slow degradable fraction and “c” is the outflow rate. The in vitro DM and CP degradability of rumen undegradable residue collected after 24 and 48 hour incubation was determined by sequential in vitro digestion in pepsin (abomasal) and pancreatin (small intestine) solutions. DM and CP content differed significantly (P ˂ 0.05). D. cinerea leaves had higher levels of DM and CP content than B. thonningii leaves. DM and CP disappearance increased (P < 0.01) as the incubation period increased. There was no difference (P > 0.05) in soluble fraction ‘a’ and ‘b’ of DM of the two species. The CP components for both fraction ‘a’ and ‘b’ differed significantly (P < 0.01) for CP among the two species. There was significant difference (P < 0.01) in post-ruminal digestibility among the two species. CP digestibility of B. thonningii and D. cinerea leaves was reduced (P < 0.01). In conclusion, B. thonningii and D. cinerea leaves showed significant difference based on their fermentation kinetics and in vitro digestibility, suggesting a good nutritional quality which can be used as protein source for ruminants in dry season and supplement to low-quality diets. / NRF