This study investigated the impact of precursor supplementation and incubation time on the quality of palm stem pith silage (nutrient content, in vitro digestibility, and rumen fermentability). A factorial complete randomised design was applied, and the first factor included precursor supplements (D1 – empty bunch ash filtrate, D2 – chicken faeces + urea, D3 – effective microorganism + molasses + urea), while the second factor was incubation periods (B1 – 7 days, B2 – 14 days, B3 – 21 days). Each treatment was replicated 3 times, resulting in 27 experimental units. The results revealed significant main effects of precursor supplementation, incubation time and their interaction on various silage parameters. In particular, a clear interaction (P < 0.01) was observed between precursor supplementation and duration of incubation, indicating significant synergistic effects on nutrient content (dry matter, organic matter, crude protein, crude fibre, extract ether and nitrogen-free extract), digestibility (organic matter and dry matter) and rumen fermentability (NH₃ concentration). Specifically, the combination of effective microorganism + molasses + urea supplementation, with a 14-day incubation period, emerged as the most effective strategy for enhancing silage quality. These findings highlight the crucial role of considering treatment interaction factors in optimising silage production processes.