This research involved two distinct experiments: the first (Experiment 1) aimed to identify ruminal bacteria capable of breaking down cyanide, while the second (Experiment 2) assessed how fresh cassava root (FCR) and sulfur-enriched pellets (PELFUR) affect cyanide levels, gas generation traits, in vitro degradation, and ruminal fermentation. In Experiment 1, a completely randomized design (CRD) was used to test bacterial tolerance at cyanide concentrations of 0, 150, 300, and 450 ppm. Experiment 2 followed a 5 × 3 factorial CRD design. Factor A represented the inclusion of FCR at 0, 260, 350, 440, and 530 g/kg of dry matter (DM), and Factor B denoted PELFUR at 0, 15, and 30 g/kg DM.
In Experiment 1, varying cyanide doses significantly influenced the growth of cyanide-metabolizing bacteria in the rumen (p < 0.05). Raising cyanide from 0 to 150 ppm and 150 to 300 ppm led to bacterial growth increases of 38.2% and 15.0%, respectively. For Experiment 2, no significant interaction between FCR and PELFUR was found regarding gas production (p > 0.05). FCR inclusion above 260 g/kg DM promoted higher total gas output (p < 0.05). Likewise, elevating PELFUR from 15 to 30 g/kg DM enhanced cumulative gas yield compared with 0 g/kg (p < 0.05). PELFUR also lowered cyanide concentration in rumen fluid (p < 0.05). Dry matter and organic matter digestibility rose after 12 and 24 h incubation, especially when 15 g PELFUR/kg DM was combined with 440 g FCR/kg DM (p < 0.05). The distribution of volatile fatty acids—acetic (C2), propionic (C3), and butyric acids—varied significantly among FCR levels (p < 0.05). In summary, this study presents the first evidence of ruminal bacteria utilizing cyanide as a nitrogen source for growth. Using 530 g FCR/kg DM along with 30 g PELFUR/kg DM enhanced cumulative gas output, bacterial population, digestibility, propionate proportion, and cyanide degradation rate.
