Rice straw pretreatment using cow breeding wastewater for methane production

•Cow breeding wastewater pretreatment enhanced the methane yield of rice straw.•Straw pretreatment using breeding wastewater obtained favorable lignin removal.•Filtering wastewater with straw increased the NH4+-N content during pretreatment.•Wastewater pretreatment of straw under semi-sealed conditions was feasible.•It was feasible to replace pretreatment reagents with cow breeding wastewater.