Plant bioactive compounds as functional feed additives for improving livestock and poultry production: review

The administration of antibiotics to enhance growth and prevent diseases in livestock and poultry has elicited concerns over antimicrobial resistance and its implications for public health. The escalating demands on the livestock and poultry sectors necessitate enhanced productivity, diminished economic losses, and the guarantee of food safety for human consumption. Plant bioactive compounds (PBCs) have developed as safe and sustainable alternatives to antibiotics that enhance growth, bolster animal health, and boost productivity without jeopardizing food safety. PBCs represent a diverse group of secondary metabolites-including phenolics, terpenoids, polysaccharides, and organosulfur compounds-that exhibit a wide range of biological activities relevant to livestock and poultry nutrition and health. Recent studies have shown that supplementing animals with PBCs as feed additives, either as crude extracts or individual compounds, improves growth performance, nutrient utilization and modulates gut microbiota, while exerting antioxidant, anti-inflammatory, antimicrobial, and immunoregulatory effects, and thereby enhancing overall resilience of animals. The multifunctional properties of PBCs, along with the reduced risk of resistance development, position them as promising candidates for next-generation feed additives for livestock and poultry production. However, challenges remain regarding optimal concentration, variability in bioavailability, stability during feed processing, and the standardization of active components. Here, we discuss the major PBCs and their potential as functional feed additives to improve livestock and poultry production. We further highlight research gaps and outline future prospects required to promote their integration into sustainable animal production.