Abstract
The aim of this study was to determine the nutritional value of protein from the seeds of yellow lupine (Lupinus luteus) and blue lupine (Lupinus angustifolius) cultivars, contained in diets fed to rats. The experimental diets were based on the seeds of three yellow lupine (Mister, Markiz, Taper) or three blue lupine (Sonet, Boruta, Elf) cultivars as the only or main protein source. The nutritional value of the diets was determined based on their chemical composition and alkaloid and oligosaccharide concentrations. Lupine seeds were fed to male Wistar rats with initial body weight of approx. 112 g. Alkaloid concentrations in yellow lupine and blue lupine seeds were 0.07-0.09 g kg-1 DM and 0.26-0.39 g kg-1 DM, respectively. Oligosaccharide concentrations in yellow and blue lupine seeds were 108.0-108.9 and 65.4-67.6 g kg-1 DM, respectively. The inclusion of lupine seeds in rat diets increased fecal and urinary nitrogen losses, and decreased nitrogen retention by approx. 10%. The diets based on yellow or blue lupine seeds were characterized by lower nitrogen digestibility and lower biological value of protein than the control diet containing casein.