Zinc replacement strategies for preventing piglet diarrhea
Department of Animal Science, Aarhus University, Foulum, Denmark
Several feed additives are proposed as potential substitutes for zinc oxide (ZnO) to reduce incidence of post-weaning diarrhea (PWD) and provide protection against intestinal injury. Any reduction of dietary zinc will result in less excretion of zinc to the feces, and thereby in reduced contamination of the agricultural soil and antimicrobial resistance. Contrary to medical drugs, feed additives apply to improve the performance of healthy animals or to cover their physiological requirements. This presentation aims to evaluate the potential of commonly suggested feed additives for their effect on improving gut health, and in that way reducing PWD. Although the mechanisms behind the success of high dietary ZnO levels in terms of limiting PWD is still not clear, it seems that ZnO has a positive impact on the stability and diversity of the gastrointestinal microbiota, which contributes to an increased colonization resistance against pathogens, as well as an indirect effect on host-immunity and epithelial barrier function. While many potential feed additives share several of the mechanisms by which ZnO is proposed to prevent PWD, there is probably not a single feed additive, which can replace ZnO for its capability to prevent diarrhea. Thus, the ideal feed additive for enhancing gut health of pigs is probably a cocktail of various antibacterial and immunomodulatory agents targeting specific challenges as E. coli infection progresses in piglets post weaning, and they may be applied early in life in order to efficiently influence in the established matrix interaction between the microbiota and the host.