Nutrional value and antinutritional components of whole and ethanol extracted Moringa oleifera leaves

Abstract

Chemical constituents, organic matter digestibility, gross and metabolizable energy, rumen degradable and undegradable nitrogen, amino acid composition, digestion kinetics (leaves, their neutral-detergent fiber and cell solubles), and antinutritional factors were determined in extracted (80% aqueous ethanol; the extract is used as a source of growth promoting factors) and unextracted Moringa oleifera leaves. The metabolizable energy and organic matter digestibility predicted from the extent of fermentation in in vitro incubation were 9.2 MJ kg⁻¹ and 75.7% for the extracted leaves and 9.5 MJ kg⁻¹ and 74.1% for the unextracted leaves. The crude protein contents of the extracted and unextracted leaves were 43.5 and 25.1% respectively. The true protein contents of these leaves were 93.8% and 81.3% of the total crude protein (non protein nitrogen contents of 2.7 and 4.7% were observed in the extracted and unextracted leaves). In vitro rumen crude protein degradability at 24 h of incubation was 44.8 and 48.6% for the extracted and unextracted leaves. One of the factors responsible for the low rumen protein degradability could be the low solubility of the proteins (about 7 and 24% of the crude protein was soluble in phosphate buffer (pH 7, 0.05 M) for the extracted and unextracted leaves). The protein insoluble in acid-detergent fiber (ADIP; protein unavailable to animals) was 13.2 and 9.8% in ADF of the extracted and unextracted leaves respectively (absolute values of 22 g and 11 g ADIP kg⁻¹ leaves). The protein potentially digestible in the intestine (PDI) was 50 and 47% of the total crude protein for the extracted and unextracted leaves respectively. The rate (h⁻¹) and potential extent (ml g⁻¹) of gas production calculated using the exponential model for the extracted and unextracted leaves were 0.0424 and 274.3, and 0.0824 and 248.5 respectively. These values for their NDF were 0.0542 and 265.8, and 0.0645 and 271.7 and for their cell solubles were 0.0338 and 286.3, and 0.089 and 242.2 respectively.

M. oleifera leaves had negligible tannins; saponins content (5.0% as diosgenin equivalent) was similar to that present in soyabean meal, and trypsin inhibitors and lectins were not detected. The phytate content was 3.1%. The ethanol extracted leaves were virtually free of tannins, lectins, trypsin inhibitors and saponins, and phytate content was 2.5%.

All essential amino acids including sulfur-containing amino acids were higher than adequate concentration when compared with recommended amino acid pattern of FAO/WHO/UNO reference protein for a 2 to 5-year-old child.