The global energy crisis has determined the need for alternative sources of energy generation. The use of biodigesters can, in addition to increasing the energy and environmental sustainability of the agricultural property, reduce dependence on external inputs for production, with the use of biofertilizer to produce animal feeds. The operation of livestock residue biodigesters includes the energy potential of biogas and the use of effluent in fertigation. This work evaluated the use of treated effluent as a biofertilizer, the optimization of biogas generation through the improvement of the biodigestion process, changing organic load and/or hydraulic retention time, to increase biogas production in quantity and quality. The project evaluated the characteristics of the biofertilizer to be applied to elephant grass cv. Capiaçu, regarding its dosage for greater forage production and improvement of soil quality. The identification of microorganisms with the greatest potential for biogas production was carried out, based on the identification of the microbial community of the biodigester. Also, the polluting potential of the effluent was determined with the verification of the presence of micro pollutants, hormones. For this verification, the project included an in vitro assay, the YES test (yeastestrogenscreen). This test is used to determine the dynamics of hormones and their metabolites, resulting from their use in reproductive management at Embrapa’s experimental station. To complement the qualitative and quantitative evaluations of hormones, a survey was carried out in commercial herd farms in Brazil, where farmers were asked about the routine use of these drugs in herds for comparing what routinely happens in farms with what was found in laboratory tests. The results of this research generated knowledge for optimizing the process of dairy manure treatment and producing biogas from biodigesters, as well as for the efficient and safe application of the effluent as biofertilizer.