Fermentation quality, microbial dynamics, and rumen degradability of total mixed ration silages containing Manihot sp’ foliage

Pornunça (Manihot sp.) is a potential forage for feeding ruminants in drylands worldwide due to its drought tolerance and favorable nutritional value. This study aimed to evaluate the quality, fermentative profile, losses, and ruminal degradability of total mixed ration (TMR) silages containing pornunça foliage as a fiber source. The treatments consisted of TMR silages with different forage-to-concentrate ratios (50:50, 60:40, 70:30, 80:20, and 100:0, DM basis), arranged in a completely randomized design with five replications. Ruminal degradability (DEG) was evaluated using three rumen-cannulated sheep (46.0 ± 2.30 kg). Exclusive ensiling of pornunça negatively affected fermentative characteristics, increasing gas and effluent losses, reducing dry matter recovery (DMR), and numerically increasing yeast and enterobacteria counts. The highest DMR was observed in the 50:50 silage (916 g/kg), likely due to lower fermentative losses. Silages with a higher concentrate proportion (50:50 and 60:40) showed greater concentrations of non-fibrous carbohydrates and higher production of organic acids, especially lactic and acetic acids. All silages exhibited propionic, acetic, and butyric acid concentrations below the maximum recommended limits for good-quality silage. These characteristics resulted in a higher soluble fraction ‘a’ and the highest effective DEG of DM and neutral detergent fiber (NDF) in the 50:50 silage. In contrast, the 100:0 silage showed a high fiber concentration, which likely contributed to its lower “a + b” fraction and reduced effective DM degradability. Despite the superior quality of the silage with a 50:50 forage-to-concentrate ratio, pornunça demonstrates high potential as a sustainable forage source for semiarid regions.