Pigs are subject to numerous health threats as they undergo various stresses at the time of weaning. At the same time, their immune system is not fully developed. Diarrhea is one of the common problems in a newly weaned group, causing substantial economic losses for producers due to the increased mortality and morbidity. Certainly, many factors can lead to post-weaning diarrhea, such as poor environmental hygiene, inappropriate feeding and infectious pathogens. Piglet diarrhea caused by Escherichia coli is one of the most common cases, also called colibacillosis.