Determining the source of anti-nutritional factor(s) found in two species of lupin ( L. albus and L. angustifolius) fed to growing pigs

Abstract

Two similar trials on two species of lupins ( Lupinus albus and L. angustifolius) were conducted using 48 growing pigs each to determine whether the source of anti-nutritional factors (ANFs) are to be found in the kernel or the hull. Pigs were grown from 15 to 47 kg liveweight. Three basal diets were formulated, the first was a soya-based diet with no lupin, the second contained 300 g full fat, dehulled lupin meal/kg diet, and the third being the same as the first but replacing 50 g sunflower husks/kg with 50 g lupin hulls/kg. The basal diets were blended in appropriate proportions, to produce a series of nine feeds (Treatments 1–9) containing different dehulled lupin and lupin hull contents. In addition, three choice feeding treatments were included to determine whether there were preferences for or against either the lupin kernel or hull. The growth performance results indicate that increasing the content of dehulled lupin in the diet caused a linear ( P<0.05) decrease in average daily growth rate (ADG) and, in the case of L. albus, a similar decrease ( P<0.05) in voluntary food intake (FI). Adding lupin hulls (maximum 50 g/kg) back to diets with different levels of dehulled lupin had a minimal effect on performance and where it did it improved performance. When given a choice between two feeds, pigs had a clear dislike for dehulled lupin-based diets even when the choice included a diet with lupin hulls. The food intake preferences and growth responses indicated that the ANFs are located in the kernel rather than in the hulls. The results of the chemical composition of the diets were inconclusive in identifying what the ANFs were, although the higher concentrations of oligosaccharides in the diets with dehulled lupin relative to those without, suggests that the oligosaccharides, raffinose and stachyose, are the main ANFs.