Abstract

Background and Aim: This study evaluated the effects of partially and totally replacing corn silage (CS) with sorghum silage (SS) cultivated on marginal land on the chemical composition and in vitro ruminal fermentation characteristics of total mixed rations (TMRs).
Methods: Five experimental diets were formulated with 0, 25, 50, 75, and 100% substitution of CS by SS. In vitro gas production (GP) kinetics, methane (CH4) emission, nutrient degradability, and fermentation parameters were measured.
Results: The asymptotic GP, GP rate, lag time, and total gas at 24 h were unaffected by sorghum inclusion (p>0.35). However, CH4 production linearly declined (p=0.045), decreasing by 19.6% at full replacement. Digestibility parameters, including truly degraded dry and organic matter, showed slight numerical improvements (2.1–2.2%) without statistical significance. Metabolizable energy, microbial biomass production, and partitioning factor were unaffected, as were ruminal pH and ammonia-N concentrations, although ammonia-N declined numerically by 14.3% at 100% replacement. Total and individual volatile fatty acid concentrations were not significantly influenced by treatment (p>0.05), but numerical shifts were noted. Acetate proportion increased, while propionate declined with increasing sorghum inclusion, resulting in a higher acetate-to-propionate ratio. Isoacid profiles showed minor fluctuations, with a tendency toward reduced isovalerate proportion (p=0.067).
Conclusion: In conclusion, replacing CS with SS cultivated on marginal land did not compromise ruminal fermentation or digestibility and resulted in a significant reduction in CH4 production. These findings support the potential of SS as a sustainable alternative to CS in ruminant feeding systems in marginal lands.

Key words: alternative feeds, rumen fermentation, CH4 emission, degradation, in vitro