Simple Summary
Post-weaning diarrhoea is one of the most common health problems affecting piglets after weaning, reducing growth and causing important economic losses for pig producers. For many years, high levels of zinc oxide were used to help control this condition, but their use has been banned in the European Union because of environmental and public health concerns. Therefore, effective alternatives are urgently needed. In this study, we evaluated a feed supplement containing specific immunoglobulin-derived binding proteins (bivalent VHH constructs) designed to provide passive immunity to virulence factors produced by enteropathogenic Escherichia coli bacteria. Two studies were conducted: one under controlled experimental conditions using an induced infection model and another in a commercial pig farm. VHH supplementation improved growth performance, reduced indicators associated with diarrhoea, and decreased the presence of bacterial virulence factors. Importantly, beneficial effects were observed not only under experimental conditions but also in a large commercial nursery. These results support the use of this nutritional strategy as a potential alternative to zinc oxide for managing post-weaning diarrhoea and improving piglet performance under practical production conditions.
Abstract
Post-weaning diarrhoea remains a major health and production challenge in pig farming, and effective alternatives to pharmacological zinc oxide are needed. This study evaluated bivalent VHH constructs as a potential dietary alternative to pharmacological zinc oxide under both controlled experimental and commercial production conditions. In Trial 1, 96 weaned piglets were orally challenged with enterotoxigenic Escherichia coli F4+ and received either a control diet, zinc-oxide-supplemented diet, or diet supplemented with bivalent VHH constructs. In Trial 2, 528 piglets were evaluated in a commercial nursery barn using the same dietary groups. In Trial 1, VHH supplementation improved post-challenge growth performance, reduced faecal EHEC counts and increased the lactobacilli-to-EHEC ratio, confirming previous evidence obtained under controlled conditions. Importantly, similar responses were observed under commercial conditions in Trial 2, where VHH-supplemented piglets showed improved faecal scores, higher average daily gain and greater final body weight. Quantile analysis further indicated that the positive response extended to the lower tail of the distribution of pen-level performance. These findings extend previous experimental evidence and demonstrate the efficacy of VHH supplementation under commercial production conditions, supporting its use as a nutritional alternative to pharmacological ZnO during the post-weaning period.