Studies on the nutritive value of cowpeas (Vigna unguiculata)

Abstract

Samples of I50 different cowpea cultivars, used in the breeding trials of the Summer Grain Institute at Potehefstroom, were analysed and found to have an average crude protein content of 28.4 ± 1.8% (range 24.5 to 33.9%). From these samples, five high- and five low-protein cowpea samples as well as a composite sample of the remaining 140 cowpea cultivars, were selected. Part of the composite sample was autoclaved for 15 min at 121°C. Only small differences were observed in the chemical composition of the experimental cowpea meals. No significant (P > 0.05) differences were found between raw and autoclaved cowpea meal either in relative nutritional value (RNV) and true protein digestibility (PTD) determined with rats, or in amino acid availability (AAA) determined with roosters. Autoclaving resulted in significant (P < 0.05) improvements in digestible energy (DE) and true metabolizable energy (TME) when determined in pigs and poultry respectively.

Monsters van 150 verskillende akkerboonkultivars, afkomstig van die kultivarstudies van die Somergraan Instituut by Potchefstroom, is ontleed en het 'n gemiddelde ruproteïen-inhoud van 28.4 ± 1.8% (24.5 tot 33.9%) gehad. Vyf hoë- en vyf laeproteien-akkerboonmonsters en 'n monster, saamgestel uit die oorblywende 140 kultivarmonsters, is geselekteer. 'n Gedeelte van die saamgestelde monster is vir 15 min met stoom teen 121°C behandel. Slegs klein verskille in die chemiese samestelling van die eksperimentele akkerboonmele is gevind. Geen betekenisvolle (P > 0.05) verskille is gevind tussen rou en stoombehandelde akkerbone in relatiewe voedingswaarde en ware proteïenverteerbaarheid, soos met rotte bepaal, en aminosuurbeskikbaarheid, soos met pluimvee bepaal nie. Stoombehandeling het 'n betekenisvolle (P < 0.05) verbetering in verteerbare energie by varke en ware metaboliseerbare energie by pluimvee tot gevolg gehad.

Keywords: Amino acid availability, cowpea meal, digestible energy, pigs, poultry, rats, relative nutritive value, true metabolizable energy, true protein digestibility.