en Infectious diseases Infectious diseases پژوهشي Research <strong>Introduction:</strong> Post-weaning diarrhea (PWD) in pigs is a worldwide economically important disease, which is frequently controlled using antibiotics. However, emergence of antimicrobial resistance in <em>Escherichia coli</em> strains urges the need for alternative control measures, such as adapted feeding strategies, pre- and probiotics, organic acids, MCFAs or immunization. <strong>Methods:</strong> Different&nbsp; alternative control strategies such as active immunization of piglets against PWD with an <em>E. coli</em> F4 vaccine (Coliprotec&reg; F4; Elanco) combined with high energy and protein diets, addition of nutraceuticals (medium chain fatty acids (MCFAs), organic acids and additional fibers) or supplementation of ZnO were evaluated for their efficacy against PWD due to F4 enterotoxigenic <em>E. coli</em> (F4-ETEC) under field conditions. <strong>Results:</strong> ZnO-supplemented piglets had a lower overall end weight and lower average daily weight gain, as compared to <em>E. coli</em> vaccinated piglets. The <em>E. coli</em> vaccinated group with normal energy and protein diet had the lowest clinical scores, whereas piglets fed a ZnO-supplemented diet had intermediate fecal clinical scores. All <em>E. coli</em> vaccinated groups had a low number of antibiotic treatments. In the nutraceutical group, clinical scores were much higher, indicating more severe clinical diarrhea, which needed additional antibiotic intervention. <strong>Conclusions:</strong> The present study demonstrated the efficacy of an oral live non-pathogenic <em>E. coli</em> F4 vaccine for active immunization of piglets against PWD due to F4-ETEC under field conditions. Different feeding strategies had no significant effect on the clinical outcome and performance parameters of <em>E. coli</em> vaccinated piglets. F4-ETEC, PWD, E. coli F4 vaccine, performance, high energy and protein diets 1 9 http://vacres.pasteur.ac.ir/browse.php?a_code=A-10-1133-1&slc_lang=en&sid=1 Frédéric Vangroenweghe vangroenweghe.frederic@telenet.be 0000-0003-0569-9503 Yes Elanco Benelux - BU Food AnimalsPlantijn en Moretuslei 1 - 2018 Antwerpen Olivier Thas olivier.thas@uhasselt.be 0000-0001-6442-4089 No 1. I-BioStat, Data Science Institute, Hasselt University, Campus Diepenbeek, Agoralaan gebouw D, 3590 Diepenbeek, Belgium. 2. Department of Data Analysis and Mathematical Modelling, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium. 3. National Institute of Applied Statistics Research Australia (NIASRA), University of Wollongong, Northfields Ave, Wollongong, NSW 2522, Australia.