Research Progress on the Mechanism of Protein Glycosylation Modification in Regulating Intestinal Health of Livestock and Poultry

Since the implementation of the "antibiotic ban order" for feed in China in 2020, the livestock and poultry breeding industry has faced numerous challenges, including impaired animal growth and development, reduced feed conversion efficiency, and decreased disease resistance. Among these, the intestinal tract, as the core organ for nutrient absorption and immune defense in the body, has increasingly prominent health issues, manifested as damaged intestinal barriers, frequent inflammatory responses, and imbalances in microbial communities. The health of the intestinal tract is crucial for overall production performance, and the intestinal mucosal barrier, as the first line of defense against pathogens and toxins, maintains homeostasis through multiple mechanisms, such as mucus layer, tight junctions, immune regulation, and microbial interactions. In this process, protein O-glycosylation modification plays a key role, as it determines the structural and functional diversity of mucin proteins and directly affects barrier integrity. In recent years, with the rapid development of glycomics technology, the complex structure of glycosylation modifications can be more accurately analyzed, laying the foundation for its application in nutritional intervention and disease prevention. This article systematically summarized the main types of protein glycosylation modifications and their structural characteristics, and focused on the regional distribution differences and functional characteristics of mucin O-glycosylation modifications in the intestinal mucus layer. The article thoroughly analyzed the mechanisms of action of three important O-glycosylation subtypes (sialylation, sulfation, and fucosylation) in the intestinal mucosal barrier: Sialylation enhanced the negative charge of the mucus layer, inhibited pathogen adhesion, and regulated the function of immunoglobulins; Sulfation modification improved the stability and anti-degradation ability of the mucus layer and affected microbial recognition and colonization; Fucosylation provided carbon sources for symbiotic bacteria and activates immune axes (such as AHR/IL-22) to participate in host defense. In addition, this article systematically reviewed the latest research progress of O-glycosylation in regulating the immune response and microbial interactions in livestock and poultry, such as in models of necrotic enteritis and Salmonella infection, O-glycosylation abnormalities could lead to impaired intestinal barrier function, and supplementing specific monosaccharides (mannose, and fucosamine) could alleviate inflammation by repairing the glycan chain structure. Although significant progress has been made in related research, the precise analysis of the glycosylation modification structure and the targeted regulation of key glycosyltransferases (Fut2, St3gal, etc.) through nutritional strategies still face challenges. In the future, it is necessary to further integrate multi-omics technologies, artificial intelligence models, and synthetic biology approaches to deeply reveal the molecular mechanism of glycosylation modification in the occurrence and development of intestinal diseases in livestock and poultry, providing new ideas for the precise prevention and control of issues, such as diarrhea after antibiotic ban, and ultimately helping to improve the intestinal health level and breeding efficiency of livestock.