Editorial: functional nutritional strategies as alternatives to antimicrobials

The challenge of antimicrobial resistance (AMR) has emerged as one of the major concerns within the One Health perspective, and it is currently being addressed at multiple levels by international organizations, policymakers, and the scientific community. Important efforts focus on both human and animal health, promoting the judicious use of antimicrobials and encouraging the development of sustainable alternatives to safeguard public health, animal welfare, and environmental sustainability. In particular, over the past few decades, scientific research has increasingly focused on exploring innovative nutritional interventions as functional strategies to enhance disease prevention, promote overall animal health, reduce the need for antibiotics, and mitigate the spread of AMR. This Research Topic includes 19 contributions focused on the potential of functional nutritional strategies as promising alternatives to antibiotic treatments for both livestock and companion animals. Several articles in this Research Topic explore the roles of probiotics, prebiotics, postbiotics, and natural and plant-derived compounds in modulating the microbiome, immune responses, and metabolic pathways. These studies highlight how dietary supplementation can strengthen host defenses, mitigate oxidative stress, and reduce the incidence of disease conditions. Taken together, the contributions to this Research Topic on swine highlight the multi-mechanistic modes of action of functional compounds, encompassing anti-inflammatory and antioxidant effects, enhancement of barrier function, and modulation of the microbiome and metabolome axis. Several nutritional strategies have been investigated to mitigate weaning stress, shape the gut microbiota and metabolite profiles, and ultimately improve animal performance and health. For instance, microencapsulated essential oils were shown to support both health and performance in weaned piglets (Xu et al.), while essential oil from Alpinia oxyphylla modulated immunity, antioxidant capacity, and the gut microbiota profile in fattening pigs (Chen et al.). Probiotic supplementation increased beneficial short-chain fatty acids in the feces and improved average daily gain in weaned piglets (Zhao et al.). Another study on piglets demonstrated that oral supplementation with an egg yolk immunoglobulin-based product improved growth performance and mucosal immunity, which was particularly beneficial for low-birth-weight neonates as it enhanced β-defensin expression, modulated inflammatory responses, and stabilized intestinal barrier function during the pre-weaning period (Lothong et al.). Maternal nutrition has also emerged as a critical determinant of offspring resilience. Fang et al. showed that perinatal fish oil supplementation in sows protected piglets from LPS-induced damage, while Daneshi et al. revealed that maternal one-carbon metabolite supplementation modulated the expression of antimicrobial peptides in both fetal and maternal tissues, suggesting an epigenetic route through which perinatal nutrition can shape innate immunity. Plant-derived polyphenols also confirmed their beneficial properties. Supplementation with Ampelopsis grossedentata extract improved intestinal morphology, enhanced antioxidant status, and modulated the gut microbiota in growing-finishing pigs (Liu, Zhang et al.). Two complementary studies focused on seaweed supplementation. The first included an in vivo trial with post-weaning piglets, demonstrating that a blend of Ascophyllum nodosum and Phymatolithon calcareum protected against F4+ E. coli infection by improving gut morphology and antioxidant status (Dell'Anno et al.), while a second companion in vitro characterization and zootechnical trial confirmed that the bioactive compounds retain