Effect of genotypes on agronomic and antinutritional traits of Lupinus albus L. for livestock

Lupin species (Lupinus spp.) could represent a realistic and sustainable alternative protein source in both monogastric and ruminant feeds, capable of replacing soy without loss of quantity and quality of livestock products. However, a drawback of lupin seed quality are the antinutritional factors (ANFs), namely the alkaloid compounds. Aim of this study was to explore the productive traits and the quinolizidine alkaloids (QAs) in four genotypes of Lupinus albus L. grown in the Mediterranean environment. Two recently released varieties (Volos and Luxor) and two ecotypes from South-Italy (Ecotype F and Ecotype G) were compared in a field trial. Seed yield (SY) and thousand seed weight (TSW) were evaluated at seed physiological maturity. QAs analysis was performed by HR-GC/MS (LOQ: 0.01 mg/100 g). Data were subjected to a one-way ANOVA and means were separated by the Tukey HSD test (p≤0.05). SY was the significantly highest in Luxor and Ecotype G (2.27 and 1.81 Mg/ha), and the lowest in Volos (1.02 Mg/ha). On the contrary, the TSW was the highest in Volos (347.2 g) and the lowest in the two Ecotypes (315.4 g, on average) Luxor (6 mg/100 g) and Volos (5 mg/100 g) showed very low concentrations of total QAs, while Ecotype F (250 mg/100) and G (202 mg/100 g) showed the highest values. Lupanine and angustifoline were significantly higher in Ecotypes F (183 and 39 mg/100 g) and G (146 and 29 mg/100 g) than in Luxor (5 and 0.3 mg/100 g) and Volos (4 and 0.2 mg/100 g). Other QAs (sparteine, multiflorine, 13-alpha-hydroxylupanine, 13-alpha-hydroxymultiflorine and angeloxylupanine) were below the limit of toxicity (0.02%) for animal consumption, nonetheless, the two ecotypes showed the highest content. This study underlines the importance of genotype selection for a safe and sustainable animal nutrition. Among tested genotypes, present findings suggests Luxor well balanced between productive and ANFs traits, while Volos was characterized by a low productivity and the two ecotypes by too high ANFs content. Further effort is needed to breed new white lupin genotypes well adapted to a wide range of climatic conditions and resilient to abiotic adversities.