Alternatives of zinc oxide in piglet diets Literature review

Based on the FAO-OECD 2019-2028 projections, pork remains the main animal origin protein source both in developed and developing countries. Post-weaning diarrhoea - which occurs during the first two weeks after weaning - is one of the most important health issues in pig production. It leads to lower body weight gain, increased mortality and economic losses due to medical treatment. The main aetiological agent is enterotoxigenic E. coil (K88). In the European Union administration of medical level of ZnO (2500-3000 mg/kg) was banned in June 2022. Therapeutic doses of ZnO played a key role in prevention due to its antimicrobial effect and positive impact on the whole gastrointestinal tract. The most important reasons for this decision were the pollution of the environment and the increased risk of antimicrobial resistance. Thus, novel strategies are needed to manage post-weaning diarrhoea in piglets. In recent years, several in vitro and in vivo methods have been investigated to prevent post-weaning diarrhoea. Among these probiotics, prebiotics, and organic acids are well known. While others such as plant extracts, essential oils, bacteriophages, nano zinc particles, or antimicrobial peptides are less likely to be used in the pig industry due to excessive costs and lack of practical application. This review summarises the most important feed additives which may help to reduce the incidence of post-weaning diarrhoea, thus reducing antibiotic use. However, the efficacy of these methods depends on several factors such as additive dose, feed composition, management, and health status of the pigs. Dietary methods such as increased fibre or reduced protein content of diet are not addressed in this review. Efficient alternatives to the therapeutic dose of ZnO are probably the combinations of different tools and strategies.