Extrusion cooking improves the metabolisable energy of faba beans and the amino acid digestibility in broilers

The study was conducted to investigate the nutritional value of 5 cultivars of Vicia faba L. seeds. The study group included 132 male one-day-old Ross 308 chickens. The birds were randomly assigned to 11 dietary treatments (12 replications in each). Birds were kept in individual cages. Nutrient digestibility was calculated using the difference method. From day 1 to 16, birds received only basal diets. From day 17 to 21, in 10 of the treatments, diets contained faba bean meal in raw or extruded form (Merlin, Olga, Albus, Amulet, Kasztelan) and the basal diet in the ratio 40:60. On days 19 and 20, excreta were individually collected, and then all chickens were sacrificed and ileal digesta were sampled for determination of ileal digestibility. The apparent metabolizable energy (AMEN) of raw faba bean seeds ranged from 8.12 to 12.16 MJ/kg; the lowest was determined for the Albus and the highest for the Amulet cultivars. Albus faba bean contained more crude protein (347 g/kg DM) than the other cultivars. The lowest concentration of crude protein was determined in cv. Kasztelan (281 g/kg DM). The AMEN of faba beans was negatively correlated with their content of oligosaccharides (r = −0.80; P ≤ 0.001), raffinose (r = −0.79; P ≤ 0.001) and phytic P (r = −0.55; P ≤ 0.001). Similar negative correlations were observed with respect to the apparent digestibility of dry matter, starch, crude protein and the ileal amino acid digestibility. Extrusion cooking of faba beans decreased their concentration of NDF, ether extracts, trypsin inhibitor, phytic P and resistant starch as well as total and free sialic acid in digesta (P ≤ 0.05). Extrusion improved the AMEN values of raw faba bean seeds and the nutrient digestibility in broilers (P ≤ 0.05).