In vitro digestibility and gas production characteristics of Hedysarum flexuosum ecotypes from Northwestern Morocco

This work is aimed to study the in vitro digestibility of ten ecotypes of Hedysarum flexuosum which are collected from different ecological sites in the northwest of Morocco. In vitro incubation of the samples during 72 hours revealed that the gas production of the ecotypes harvested at the vegetative and the budding stage (185.28 and 195.08 mL /g DM respectively) are significantly higher (P 0.001) than that obtained at the blooming (162.90 mL/g DM). The ecotypes have a very variable fermentation profiles. Indeed, the potential gas production varies from 187.74 mL (with E7) to 153.98 mL (with E5). The rate of degradation which varies from 0.128 (E6) to 0.096 h^-1 (E9) is significantly affected (P 0.001) by the fermentation ability of each ecotype. The resulting organic matter digestibility decreases very significantly (P 0.001) with the plant growth (77.61% vs 68.63% and 55.91% respectively for the vegetative, the budding and the blooming stage), and the production of microbial biomass drops by 55.57% when passing from the vegetative to the blooming stage (238.09 mg against 105.79 mg respectively). The ecotype E10 showed the highest level of digestibility. But in general, the average OMD varies slightly and insignificantly (P 0.05) from an ecotype to another (from 71.32% for E10 to 65.44% for E3), while the PBM varies significantly within the ecotypes (from 189.97 to 146.91 mg /g DM respectively for E6 and E7; P 0.001), indicating a wide variability in dry matter quality of these ecotypes. The results show that this legume constitutes an important nutritional feeding resource, particularly at the vegetative stage. However, the use of this legume at the budding stage presents the advantage of an intermediate quality associated with a relatively higher level of quantitative production (10.50% vs 8.17% of dry matter).