In recent years, the biological production of hydrogen (H2) and methane (CH4) in two-stage anaerobic systems has received increasing attention. In this work we evaluated in batch systems at laboratory scale the effect of decoupling the H2 and CH4 production phases on biogas yield. Scotta, a byproduct of ricotta cheese production, in co-digestion with pig slurry was used as substrate. Conventional anaerobic digestion (AD) at neutrality (U) was compared with dark fermentation followed by AD (two-stage AD, D). Four different inoculum sources were also compared, in U and in D. Methane amounts of 551 NmL g-1 volatile solids were measured on average in the D treatment at the end of AD. The process was faster in the reactors inoculated with methanogenic consortia. In the U treatment, only limited amounts of CH4 could be produced, due to excessive acidification of the medium. Two-stage AD of pig slurry + scotta with selected methanogenic consortia has permitted faster production of higher CH4 amounts than conventional AD.