Abstract: As the scale of livestock and poultry farming expands and intensive farming methods become more widespread,the frequent occurrence of bacterial diseases and the problem of antimicrobial resistance due to antibiotic overuse have become increasingly prominent.Reducing the use of antibiotics has become an urgent issue in the livestock industry,making the exploration of green and efficient “antibiotic reduction and replacement” farming models particularly pressing.Probiotics,as a type of living microorganisms that can colonize and have beneficial effects in the host’s body,have garnered widespread attention for their role in animal health management.These actions effectively reduce the reliance of the livestock industry on antibiotics and help improve animal health,offering an ideal alternative to address the issue of antimicrobial resistance.However,the application of probiotics in livestock and poultry farming still faces numerous challenges,including concerns about the safety and stability of probiotics,lack of market regulation,and inefficiencies in strain selection and renewal.This article provides a systematic review of the currently common probiotic species and explores their mechanisms of action in depth.Probiotics exert their beneficial effects through various mechanisms,including promoting nutrient absorption,generating short-chain fatty acids,competitively inhibiting pathogenic bacteria,and regulating immune functions.Future research should focus on addressing these issues to promote the widespread application of probiotics in livestock and poultry farming.Therefore,probiotics hold great potential and application prospects in the livestock industry,with the potential to provide new solutions for addressing antibiotic overuse and microbial resistance problems.

Key words: probiotics; antibacterial; immune function; livestock and poultry breeding; engineered probiotics