Sustainable transformation of recycled manure solids: effects of lime and neem oil-based bedding conditioners on physicochemical and microbial properties

The use of recycled manure solids (RMS) as bedding material offers affordability, environmental benefits, and availability, but high moisture content can promote microbial growth. This in vitro study investigated the effects of moisture levels (20% and 30%), bedding depths (10, 15, and 20 cm), and treatments with lime and neem oil (10% concentration) applied weekly or every alternate day. Key metrics assessed included water holding capacity (WHC), porosity, bulk density, and coefficient of friction (CoF). Results showed that RMS with a 20 cm depth had lower WHC and porosity but higher bulk density compared to shallower depths. Neem oil treatment led to lower bacterial counts, including total bacteria, coliforms, E. coli, Staphylococcus spp., and Streptococcus spp., compared with control and lime-treated RMS. However, lime influenced bacterial dynamics, with alternate-day treatments showing more pronounced reductions in microbial populations over time. Optimal conditions—20% moisture, 20 cm bedding depth, and 10% lime applied on alternate days—resulted in significantly lower E. coli counts, with bacterial levels remaining low for up to 7 days. Thus, this approach enhances the safety and efficacy of RMS as bedding material.