Methods for improving the health of agricultural poultry are provided. For example, methods including selecting specific bacteria to form a probiotic for the administration with coccidiosis vaccines for the reduction of adverse effects associated with the coccidiosis vaccines are disclosed. In accordance with various aspects of the present disclosure, a bacterial isolate, probiotic and or treatment may be obtained by novel screening methods resulting in products that are advantageously administered with or about the same time as a coccidiosis vaccine.