The chemical composition and nutritive value of low-alkaloid varieties of white lupin: 2. Oligosaccharides, phytates, fatty acids and biological value of protein

Abstract

The oligosaccharide content, fatty acid and amino acid compositions, protein digestibility and growth efficiency were determined in three low-alkaloid varieties of white lupin from the 1993 and 1994 harvest (Wat and Hetman) and the 1992 and 1993 harvest (Bardo). The α-galactoside content was relatively low (7.1-8.6% DM). Phytates constituted 0.7 to 0.9% of Wat and Bardo seeds, and from 1.2 to 1.6% of Hetman seeds. Saturated fatty acids comprised 13-18% of total fatty acids, monounsaturated fatty acids 51-57%, and polyunsaturated fatty acids, 27-35%. The lysine content was relatively low (4.70-5.25 g/16 g N), while the limiting amino acid was methionine. The chemical score (CS) calculated for methionine and cystine ranged from 35 to 45% as related to egg protein and 35 to 41% in relation to the ideal protein for pigs. The true digestibility coefficient (TD, 83-86%) and the protein efficiency ratio (PER) for seeds supplemented with methionine (1.99-2.19) did not differ significantly. The obtained results do not, however, point to intervarietal differences in oligosaccharide content and protein and fat quality. However, significant variability in the characteristics was found, depending on the year of harvest.