Effects Of Chemical Treatment On Nutrient Content And Palatability Of Senegalia Mellifera And Catophractes Alexandrii Bush-Based Feeds

ABSTRACT

The objectives of this study were to determine: (1) the chemical composition of untreated Senegalia mellifera and Catophractes alexandrii; (2) the effect of NaOH and urea treatment at different levels (0%, 4%, 6% and 8%) on chemical composition of S. mellifera milled samples; (3) the nutrient composition of formulated diets from chemically and fibrolytic enzyme treated S. mellifera samples; (4) palatability of the feeds developed from S. mellifera, when fed to weaned Damara sheep. Samples consisting of small branches and twigs were analysed for chemical composition. Samples of S. mellifera were also treated for 21 days and the chemical composition was determined. Feed formulated from treated and untreated S. mellifera was assessed for palatability over 12 days in Damara sheep. The results showed that S. mellifera had a higher (P < 0.05) concentration of CP, NDF, ash and Ca than C. alexandrii. The concentration (g/kg DM) for S. mellifera were: CP (147.42 ± 0.37), NDF (653.63 ± 0.41) and ash (52.27 ± 0.11). Chemical composition (DM, OM, CP, EE, ADF, NDF, ash) of treated S. mellifera was influenced (P < 0.0001) by treatment. Treatment with 4% NaOH, 4% urea, 6% urea and 8% urea increased (P < 0.05) CP concentration compared to control. Formulated diets differed (P < 0.05) in their DM, OM, EE, NDF, ADF and ash. The control diet had higher (P < 0.05) NDF concentration compared to diets with 4% urea or 4% NaOH. Feed intake was influenced (P < 0.05) by day and diet x day interactions. Urea (8%) and NaOH (4%) treatment improved the chemical composition and palatability for S. mellifera feed, but the reaction conditions including chemicals, concentration, moisture content, pH and duration need to be optimized, to allow greater reduction of the lignin concentration.

Keywords: Senegalia mellifera, Catophractes alexandrii, encroacher bush, palatability, fibre.