Assessing the impact of Samanea tubulosa trees on methane emissions and its potential as a feed supplement for ruminants in silvopastoral systems

Silvopastoral systems (SPS) have been recognized for their multiple benefits, including animal welfare, performance, greenhouse gas mitigation, forage quality, and overall ecosystem services. However, the availability of native tree components for SPS is limited, leading to the prevalent use of exotic species. This study aimed to investigate the potential of the native leguminous tree, Samanea tubulosa, in SPS for sustainable livestock production. Chemical-bromatological analysis of S. tubulosa fruits revealed a high crude protein content and non-structural carbohydrates (NSC). An in vivo assay with Dorper lambs showed that increasing levels of S. tubulosa in diets had a linear effect on both neutral detergent fiber (NDF) and NSC intake, with reduced NDF digestibility. However, no significant effects were observed on dry matter, organic matter, or crude protein digestibility. Moreover, methane (CH4) emissions decreased with increasing S. tubulosa inclusion, with daily CH4 emissions being up to 39% lower in animals fed with S. tubulosa compared to those without. Dendrometric characteristics of S. tubulosa trees indicated an average height of 8.79 m and a canopy area of 92.04 m2 when in pasture, with an average fruit production of 56 kg per tree, allowing for the inclusion of 108 trees per hectare. The study highlights the potential of S. tubulosa as a natural feed supplement for ruminants in SPS during the dry season, offering environmental and economic benefits. The integration of this native species into grazing systems can promote sustainable livestock production practices while contributing to the conservation of Brazilian biomes.