Phenolic composition of Hedysarum flexuosum (Sulla) in Northwestern Morocco

Ten ecotypes of Sulla (Hedysarum flexuosum) from northwestern Morocco have been installed in the experimental station of INRA. At the vegetative stage, the budding and at the flowering stage, samplings were done to estimate the phenolic composition of this plant. The result shows that Hedysarum flexuosum is characterized by moderate levels of extractable phenolic compounds which vary significantly with the stage of maturation and also with the locality of the ecotype. Indeed, from the vegetative stage to the flowering, the total phenol content (TP) decreases from 2.60% to 0.92 %DM. The decrease is also from 1.31% to 0.32% for total tannins (TT) and from 0.79% to 0.17% for hydrolyzable tannins (HT). On the other hand, the condensed tannins (CT) content increased at the budding stage (0.82% vs 0.54 %DM) and thereafter decreased significantly at the flowering (0.14 %DM). Depending upon the ecotypes, the contents of TP and TT are ranging from 2.29% to 1.66% and from 1.09% to 0.63 %DM respectively. The ecotypes are also characterized by lower concentrations of CT with recorded values varying from 0.66% to 0.32%. In general, these concentrations are below the minimum limit (2 %DM of CT) that might affect either the forage nutritional value or the animal’s health. However, a complementary study of non-extractable condensed tannins might reveal a fraction that could influence the palatability and the digestibility of proteins and fibers of Sulla.