A sustainable alternative grain legume for livestock: agronomic and nutritional traits of three lupin (Lupinus spp.) species

With the aim of evaluating lupin grain as a sustainable source of nutrient and bioactive compounds for animal feeding, the main agronomic traits, nutrients and antioxidant phenols of Lupinus albus L. (Luxor), Lupinus luteus L. (Dukat) and Lupinus angustifolius L. (Wonga), grown side-by-side in the Mediterranean area, were studied. Proximate composition was determined using the official methods of analyses, fatty acid profile by gas chromatography, total phenolic content (TPC) and the scavenging activity (DPPH• and ABTS•+) by spectrophotometric assays. A one-way ANOVA was used to assess the significance of accessions effect and means were separated by the Tukey HSD test (p ≤ 0.05). Seed yield resulted significantly different among lupin species: L. albus proved to be the most productive species (2.27 Mg/ha) compared to L. luteus and L. angustifolius (1.49 and 1.77 Mg/ha, respectively) that were not significantly different. Regarding nutritional traits, L. luteus showed the significantly highest crude protein content (396 g/kg, as fed) and L. albus the highest oil content (93 g/kg, as fed) and the lowest crude fiber content (120 g/kg, as fed). The FAs resulted of nutritional interest for L. albus and L. luteus; the former showed the significantly highest content of the oleic acid (51%), the latter, the significantly highest content of linoleic acid (50%) and alfa-linolenic acid (8%). Lupinus luteus showed the significantly highest polyunsaturated FAs (58%), in particular for those of n6 (50%) and n3 series (8%), while, L. albus the highest monounsaturated FAs (58%) and the lowest saturated FAs (16%). Antioxidant properties, namely total phenolic content and scavenging activity (DPPH• and ABTS•+), were the highest in L. luteus and L. albus, respectively. The highest content of Apigenin 1 derivatives was observed in L. luteus, while the highest level of Apigenin 2 ones was determined in L. albus. Among studied species, L. albus resulted largely the most productive species showing an interesting protein, oil and unsaturated fatty acid contents, and antioxidant acitivity; L. lutes showed lower yields but emerged for polyunsaturated FAs content, and L. angustifolius did not show valuable traits compared to the other lupin species. The present data suggest that L. albus can be considered a valuable crop and feed resource for livestock.