This review provides an overview of the current research on prebiotics and their applications in animal nutrition and health. Various types of prebiotics are introduced and classified, with an analysis of agro-industrial residues as sources. The potential of prebiotics as substrates for the growth and/or activity of probiotic microorganisms, as well as their applications in animal feeds, were examined. This analysis also considered the health-promoting advantages linked to different production techniques and bioactive compounds. The mechanisms by which prebiotics alter gastrointestinal tract microbiota are discussed, specifically in terms of combating pathogenic bacteria and modulating immune cells in the gut. Investigations of the impact of prebiotics in both polygastric and monogastric animals are reported, highlighting their effects on the gut ecosystem and animal performance. This review concludes that agro-industrial residues are valuable sources of prebiotics that possess numerous beneficial health-promoting properties suitable for animal nutrition. These prebiotics can serve as a relevant substitute in the ongoing search for alternative strategies to prevent and control the presence of pathogenic bacteria in animals, particularly considering the restriction on antimicrobial growth promoters. However, further research is necessary to explore the interaction between prebiotics and probiotics in animal care and well-being, to establish systematic management of production and practical applications of these functional feed additives.

Mytilus chilensis is considered an important food source for the Chilean population and represents a considerable fraction of its aquacultural production, mainly in southern Chile’s coastal regions. This study aimed to assess the concentrations of total arsenic (tAs), lead (Pb), and cadmium (Cd), their bioaccessibility, and associated health risks in M. chilensis from the Valdivia River Estuary (VRE) in the Los Ríos Region and the Reloncaví Fjord (RF) in the Los Lagos Region. The metal concentrations were quantified using Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES). The concentrations of tAs, Cd, and Pb were 6682 ± 2018, 1592 ± 742, and 1208 ± 639 ng/g d.w., respectively. Variations in the metal concentrations were observed across areas, months, and sampling points but remained below national and international limits. No correlation was found between the metal concentrations and environmental parameters. The bioaccessibility percentages were tAs (68 ± 10%), Cd (45 ± 21%), and Pb (15 ± 4%). The tAs, Pb and Cd levels in M. chilensis from southern Chile do not represent a risk to human health.