Adaptive foraging strategy and dietary selection of goats in the Malagasy southwestern xerophytic thickets. 

Abstract

<title>Abstract</title> Xerophytic thickets are key grazing areas supporting goat herds and local livelihoods in southwestern Madagascar. This study assessed forage consumption and dietary preferences of goats to evaluate ecological–livestock interactions in these fragile ecosystems. Research was conducted in Toliara II district at two contrasting sites—a coastal zone (Soalara-Sud—SS) and a limestone plateau (Andranohinaly—AND)—during the rainy season (March 2024) and dry seasons (July and September 2024). Methods combined forage accessibility plots, continuous bite monitoring, and near-infrared reflectance spectroscopy (NIRS) for chemical composition. Goat diets showed high species richness (163 species) but were dominated by fewer than ten core species per season. Plateau herds maintained mixed herbaceous–woody diets, while coastal herds favored shrubs and trees. Two species were strongly selected: <italic>Heteropogon contortus</italic> (AND) and <italic>Solanum bumeliifolium</italic> (SS). Nutritional quality was strongly influenced by plant species, season, and functional group (herbaceous vs. shrubs/trees) (<italic>p</italic> &lt; 0.001), while geographical location had little effect (<italic>p</italic> &gt; 0.05). The most affected parameters were dry matter digestibility, ash, neutral detergent fiber, crude protein, and fat, while metabolizable energy and acid detergent fiber were moderately influenced. Forage selectivity was the main structuring factor of the feeding behavior, with goats demonstrating adaptive strategies to seasonal constraints. Results highlight (i) strong seasonal plasticity in diets despite limited site differences, (ii) nutritional trade-offs shaped by digestibility–fiber–energy optimization, and (iii) the ecological role of key shrubs as nutritional buffers. These findings underscore the need for integrated ecological–nutritional–spatiotemporal approaches for the sustainable management of xerophytic grazing systems.