Evaluation of the Nutritive Value of Some Selected Multipurpose Trees and Shrubs (MPTS)

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Acacia auriculiformis, Albizia adianthefolia, Albizia lebbeck, Albizia zygia, Cajanus cajan, Calliandra calothyrsus, Cassia siamea, Cassia spectabilis, Gliricidia sepium, and Leucaena leucocephala were evaluated for their feeding value to sheep. Their foliage was analysed for dry matter, organic matter, ash, crude protein, crude fat using AQAC (1984) methods, and for ADF, NDF, cellulose, hemicellulose and lignin using the methods of Georing and Van Soest (1970). The determinations were done for both the wet and the dry season plant harvest for comparison. The in vitro dry matter digestibility was also determined for both seasons using the methods of Tilley and Terry (1963). Foliage of Albizia zygia, Albizia lebbeck, Cassia siamea, Cassia spectabilis, Leucaena leucocephala, Gliricidia sepium and Acacia auriculiformis were harvested during the dry season, air-dried and used in a supplementary feeding trial with cassava peelings as basal diet to determine their suitability as dry season supplements for sheep. The ten MPTS differed in their nutrient composition in both seasons (P<0.01) except for the ADF for the dry season where there were no significant differences among the species. DM values ranged between 38.6 (Albizia zygia) and 20.0 (Gliricidia sepium) for the wet season and 73.3 (Gliricidia sepium) and 46.6o (Albizia lebbeck) for the dry season. Crude protein values ranged between 32.5% (Leucaena leucocephala) and 20.0% (Acacia auriculifortnis) for the wet season, and 27.5% (Leucaena leucocephala) and 17.5% (Albizia zygia) for the dry season on DM basis while the lignin values for the wet seaS°fl ranged between 31.9% (Albizia zyqia) and 7.3% (Albizia 1ebci) and the dry season values ranged between 18.5% (Albizia zygia) and 4.4% (Calliandra calothyrsus and Leucaena ieucocephala) all on DM basis. The AIDF values ranged between 45.6% (Albizia zygia) and 12.8% (Leucaena leucocephala) for the wet season and 37.9% (Albizia zygia) and 15.0% (Leucaena çocephala) for the dry season on DM basis. Crude fat however ranged between 7.0% (Cajanus caian) and 1.1% (Acacia auriculiformis) for the wet season and 12.0% (Cajanus cajan) and 2.0% (Acacia auriculiformis) for the dry season. Apart from the differences among species within a season, for each species, there was a significant difference in nutrient composition between the dry season and the wet season. Generally, ADF, crude protein and lignin decreased while crude fat and cellulose increased during the dry season. However, the t-test showed that, for ash, NDF and hemicellulose, there were no significant differences in the overall means of the ten MPTS between the wet season and the dry season. The wet season in vitro dry matter digestibility ranged between 23.5% (Acacia auriculiformis) and 75.8% (Leucaena leucocephala) while the dry season values ranged between 18.0% (Albizia zygia) and 72.5% (Cassia siamea) . For most of the species, the dry matter digestibility improved during the dry season, however, there was no significant difference between the overall means of the ten species for the two seasons. In the supplementary feeding trial, two levels were fed for each species. These are 609 and 120g air-dry weight (7.0% moisture). The unsupplemented treatment (control) had the lowest mean daily dry matter intake (60.4 g/kg W°75). The 120g supplementary levels enhanced greater intake of dry matter than their respective 60g levels. The 120g supplements enhanced total dry matter intake ranging between 76.0 g/kg W°75 (Albizia zyqia) and 69.1 g/kg W°’75 (Cassia siamea) . The 60g supplemental levels also enhanced total dry matter intake ranging between 69.5 g/kg W°75 (Albizia zygia) and 62.5 g/kg Wo75 (Cassia siamea) . Cassia siamea seemed to contain some antinutritional factor or lacked some nutrient which induced lower intake and caused drastic reduction in weight of the animals. Daily water intake of sheep ranged between 93.1 mi/kg W°75 (Albizia lebbeck and Gliricidia sepium) and 68.2 mi/kg W°75 (Cassia siamea) for 120g supplementary levels. The 60g supplementary levels ranged between 92.7 mi/kg W°75 ((Albizia lebbeck) and 58.8 mi/kg W°75 (Cassia siamea) . The control, however, induced the lowest water intake (52.5 ml/kg W°75). There was a correlation between total dry matter intake and water intake (P<0.05). There was however no significant variation in water intake among the supplementary treatments. The mean daily weight gain varied between 18 g/day Ccassia siamea) and 78 g/day (Gliricidia sepium) for 120g supplement levels and 20 g/day (Cassia siamea to 87 g/day (acacia auriculiformis) for 60g supplements. The unsupplemented treatment (control) produced weight gain of 33 g/day. The ten MPTS were ranked based on their crude protein, ADF, NDF and lignin constituents as determined for the dry season, wet season and the values of both seasons combined. cocephala exhibited best quality factors in all the three ranks.
A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirements for the award of the Degree of Master of Philosophy in Agroforestry, 1993