Nutritional and antinutritional characteristics of selected Vicia genotypes

Abstract

Mature seeds of Vicia narbonensis (91 lines), Vicia sativa (23 lines), Vicia ervilia (16 lines) and Vicia palaestina (16 lines) were evaluated for crude protein (CP), protein precipitable tannin (PPT), vanillin-HCl catechin equivalent (CE) and trypsin inhibitor activity (TIA). Other chemical and in vitro characteristics measured included ash, organic matter (OM), neutral detergent fibre (NDF), acid detergent fibre (ADF), in vitro organic digestibility (IVOMD) and in vitro dry matter (DM) digestibility (IVDMD).

Crude protein content ranged from 264.38 ± 6.34 g kg−1 DM in V. ervilia to 341.87 ± 8.55 g kg−1 DM in V. palaestina with all species showing little intraspecies variability. The DM, OM and ash contents of all the lines were similar. However, the ADF and NDF values for V. narbonensis were significantly (P < 0.05) higher than those of the other species. Mean IVDMD and IVOMD values of the species also differed significantly (P < 0.05). The higher IVDMD (90.95%) and IVOMD (88.30%) values of V. ervilia paralleled the relatively lower ADF and NDF values.

PPT was mainly restricted to V. narbonensis while none was detected in any of the lines of either V. sativa or V. ervilia. Tannin expressed as CE was no more than 8.27 g kg−1 in any of the species and seven of the 91 lines of V. narbonensis had no detectable CE levels. There was considerable intraspecies variability in CE as indicated by the high coefficients of variation (CV), which ranged from 17.48% in V. palaestina to 68.99% in V. sativa. In comparison with most conventional legumes, TIA values were generally low in all the species, ranging from 0.36 g kg−1 DM in selection IFLVP 2524 to 5.00 g kg−1 DM in IFLVS 2560. Values for TIA in V. palaestina were particularly low (0.51 ± 0.13 g kg−1 DM) and a CV of 25.86% suggests that selection for lower inhibitor levels is possible. Seed weight was significantly (P < 0.05) correlated with CE in both V. sativa and V. palaestina, while CP was weakly negatively correlated (r = −0.48) with TIA among the V. sativa genotypes. There was no significant relationship between seed weight and TIA in any of the species investigated.