PERTANIKA JOURNAL OF TROPICAL AGRICULTURAL SCIENCE

Forage crops are fundamental for ruminant sustainable production, but Thailand’s crop-livestock systems confront persistent feed shortages and low forage quality. Cultivating high-yield tropical grasses offers a practical solution, but selecting superior species requires detailed agronomic and nutritional evaluation. Urochloa grasses represent a promising resource for enhancing feed security. This study evaluated four Urochloa varieties (U. ruziziensis, U. brizantha, U. decumbens, and Mulato II) over three cutting cycles to assess growth performance, yield, nutritive value and silage quality under tropical conditions. The field study was conducted from July 2022 to April 2023 in Khon Kaen, Thailand, utilising a randomised complete block design with three replications. Grasses were harvested at 46-50 day regrowth intervals from third cutting, and fresh forage was ensiled in vacuum-sealed HDPE bags for 21 days without additives. In the third cutting, U. brizantha produced the highest fresh (16,670.83 kg ha⁻¹) and dry matter yields (4,520.83 kg ha⁻¹). U. decumbens showed the highest cell wall fraction, with NDF reaching 61.30% in the first cycle, whereas U. ruziziensis and Mulato II exhibited lower fibre contents and greater pre-ensiling digestibility (70.97% and 71.90% IVTDMD, respectively). In silage quality, U. brizantha maintained lower NH₃-N levels (0.15%), while U. ruziziensis and Mulato II demonstrated high digestibility. Therefore, U. brizantha showed exceptional yield potential, while Mulato II and U. ruziziensis exhibited desirable nutritional and fermentation characteristics. These findings provide practical guidance for selecting suitable Urochloa species for forage production and silage utilisation in tropical livestock production systems.