Potential contribution of <i>Sulla spinosissima</i> subsp. <i>capitata</i> and <i>Sulla pallida</i> as a forage crop in arid Mediterranean regions

Abstract

This study evaluated the chemical composition, mineral content, and in vitro dry and organic matter digestibility of two forage legume species from arid pastures in northeastern Morocco, namely S. spinosissima subsp. capitata and S. pallida. This is the first report assessing the nutritive value of these two pasture species. Results revealed a wide variation between selected Sulla species; in particular, the growth stage had a significant effect (P < 0.05) on most chemical traits and digestibility parameters. Comparatively, S. spinosissima had higher organic matter digestibility (72.4 %OM) at the vegetative stage in direct correlation with lower acid detergent fiber (ADF) (24.2 %DM), lower condensed tannin, (CT) (0.27 %DM), and higher crude protein (24 %DM). Conversely, S. pallida plants with a considerable amount of ADF (40.3 %DM) and CT (4.5 %DM) had lower organic matter digestibility (56.1 %OM). Both species are mineral-rich and contain satisfactory mean (g/kgDM) levels of calcium: 23.25 in S. spinosissima and 13.75 in S. pallida, and phosphorus: 1.01 in S. spinosissima and 1.53 in S. pallida. Additionally, chemical analysis of some anti-nutritional factors revealed low concentrations (mg/g) of phytate (0.19), oxalate (0.18), and nitrate (0.21), even at the flowering stage, compared with others pasture plants. The results of the present study suggest the suitability of both Sulla species, particularly S. spinosissima, for domestication to enhance pasture productivity to support small ruminant nutritional needs in arid pastures native to the Mediterranean region.