Quail manure as a supplementary feedstock to corn stover: Conjoint effect of alkaline pretreatment and co-digestion approaches on organics solubilization and methane yield

•Quail manure's viability as a co-digested substrate for corn stover was proved.•Alkaline pretreatment increased hydrolysis rate and decreased lignin of corn stover.•Synergistic co-digestion clearly arisen when “corn stover VS”/“quail manure VS” = 0.•Highest methane yield was achieved by coupling co-digestion and alkaline pretreatment.•Energy balance of best-case scenario was positive.