In vitro digestibility evaluation of Axonopus Scoparius under Ecuadorian conditions: baseline results

Axonopus scoparius, a native forage grass species of the Ecuadorian Amazon, holds significant potential as a sustainable feed resource for ruminant production systems, yet its nutritional characteristics remain insufficiently studied. This research aimed to evaluate the in vitro dry matter digestibility (IVDMD) of A. scoparius collected from six ecological zones with altitudes ranging from 280 to 945 meters above sea level. The study assessed digestibility across three incubation periods (24, 48, and 72 hours) using the established Tilley and Terry two-stage technique to simulate ruminal fermentation and post-ruminal digestion. Samples were systematically collected to represent diverse altitudinal and ecological conditions, providing insights into how environmental factors influence forage quality. Statistical analyses included analysis of variance (ANOVA), Tukey's multiple comparison tests, and regression modeling to examine the effects of incubation time and altitude on digestibility outcomes. Results demonstrated a significant increase (P < 0.01) in IVDMD with longer incubation, with mean values rising from 22.46% at 24 hours, to 30.74% at 48 hours, and reaching 37.81% after 72 hours of fermentation. Altitude was a significant factor affecting digestibility (P = 0.004); notably, samples from mid-altitude zones (600-750 m.a.s.l.) showed the highest digestibility levels, up to 42.4%, whereas lower altitude zones exhibited values as low as 26.8%. Regression analysis revealed a positive correlation between incubation time and digestibility at 72 hours (r = 0.5289, R2 = 0.2797, p = 0.0079), highlighting the importance of extended fermentation periods to capture the full nutritional potential of this grass species. While A. scoparius exhibits moderate digestibility compared to improved tropical forages, its natural adaptability to poor soils, resilience to overgrazing, and minimal input requirements position it as a valuable forage option for extensive tropical livestock systems. These preliminary findings advocate for the integration of A. scoparius into forage diversification strategies and suggest further research focusing on agronomic practices, supplementation, and genetic improvement to enhance its nutritive value.