In vitro Methane Mitigation Potential of Foliage of Fodder Trees Mixed at Two Levels with a Tropical Grass

Enteric methane (CH4) emitted by ruminant species is known as one of the main greenhouse gases produced by the agricultural sector. The objective of this study was to evaluate the chemical composition, in vitro gas production, dry matter degradation (DMD), digestibility, CO2 production and CH4 mitigation potential of five tropical tree species with novel forage potential including: Spondias mombin, Acacia pennatula, Parmentiera aculeata, Brosimum alicastrum and Bursera simaruba mixed at two levels of inclusion (15 and 30%) with a tropical grass (Pennisetum purpureum). Crude protein content was similar across treatments (135 g kg-1 DM), while P. purpureum was characterized by a high content of acid detergent fiber (335.9 g kg-1 DM) and B. simaruba by a high concentration of condensed tannins (20 g kg-1 DM). Likewise, A. pennatula and P. aculeata were characterized by a high content of cyanogenic glycosides and alkaloids respectively. Treatments SM30-PP70 (30% S. mombin + 70% P. purpureum) and BA30-PP70 (30% B. alicastrum + 70% P. purpureum) resulted in superior digestibility than P. purpureum, while in the AP30-PP70 (30% A. pennatula + 70% P. purpureum) was lower than the control treatment (P≤0.05). At 24 and 48 h, treatments that contained P. aculeata and B. alicastrum produced higher CH4 ml g-1 DOM than P. purpureum (P≤0.05). The inclusion of B. simaruba at 30% reduced CH4 at 25% compared to P. purpureum. Tropical tree species can improve the nutritional quality of ruminant rations and reduce CH4 emissions to consequently contribute to the development of sustainable ruminant production systems that generate diverse ecosystem services.