Nutritive evaluation of some Acacia tree leaves from Kenya

A study was conducted to evaluate the nutritive potential value of six species of acacia tree leaves: Acacia brevispica, nubica, tortilis, seyal, nilotica, and mellifera from Kenya. A wide variability in chemical composition, polyphenolics and gas production and in situ dry matter (DM) degradability was recorded. Crude protein (CP) content ranged from 134 to 213 g/kg DM. The content of neutral detergent fibre (NDF) and acid detergent fibre (ADF) ranged from 154 to 308 and from 114 to 251 g/kg DM, respectively, and was significantly (p < 0.05) different among the species. A. nubica had the lowest fibre, and polyphenolics concentration and the highest potential gas production and DM degradability. Mineral concentrations varied among species. All were relatively poor in phosphorus, moderate in calcium, magnesium and sulphur and rich in most microelements. Iron and selenium ranged from 132 to 459 and 13 to >100 mg/g (p < 0.05), respectively. The rate of gas production was highest in A. nubica (0.1165 h(-1)) and lowest in A. brevispica (0.0295 h(-1)). A similar trend was observed with in situ DM degradability. A strong relationship between the cell-wall fraction and gas production after 12, 24, 48, 72 and 96 was established. A weak and negative correlation was recorded between total extractable phenolics (TEPH), total extractable tannins (TET) and total condensed tannins (TCT) with gas production. The ranking order of the acacia species on the basis of their potential degradability was A. nubica > A. tortilis > A. mellifera > A. brevispica > A. seyal > A. nilotica. It is concluded that based on the moderate to high CP values and the degradation characteristics, these species have potential as livestock fodder. (C) 2000 Elsevier Science B.V. All rights reserved.