ISSUE FOCUS 36 FEED & ADDITIVE MAGAZINE January 2024 SUPPORTING INTESTINAL HEALTH AND RESILIENCE OF FARM ANIMALS The definition of “intestinal health” or “gut health” is not yet clear. It was initially proposed that gut health is the function of three major components: the diet, the mucosa, and the commensal microbiota. Later, researchers elaborated that it must include a diet that would provide sufficient nutrients, mucosa that maintains the gut integrity, and a microbial community that maintains a balanced, healthy environment (Jha et al., 2019). Since we need to limit or remove antibiotics as growth promoters, and preventive medication or metaphylaxis, significant focus must be on precise nutrition and the concept of ideal protein, and other nutrients involved in the modulation of intestinal environment and epithelial integrity. Excessive amounts of dietary protein reach the intestine, and the fermentation of it can produce various potentially toxic compounds (such as amines and ammonia), often associated with the growth of potential pathogenic bacteria (e.g., Clostridium perfringens) and the reduction of fecal counts of beneficial bifidobacteria (Yang et al., 2019). Similarly, formulation based on digestible rather than total amino acids reduce the non-digestible nitrogen reaching the intestine with an equivalent effect. On the other hand, dietary amino acids requirements are defined based on growth or production performance, and those levels might not be the optimal for the vital roles they play on the small intestinal mucosa. Particularly, glutamate, glutamine, and aspartate are the major oxidative intestinal fuel. Utilization of glycine by the small intestinal mucosa to synthesize glutathione is a very important physiological pathway, and the role of glycine as a powerful cytoprotectant has also been recognized. The major end products of methionine and cysteine metabolism are glutathione, homocysteine and taurine, which play important roles in the intestinal immune and anti-oxidative responses. Threonine is highly utilized by the gut and is particularly important for mucin synthesis and maintenance of gut barrier integrity. Emerging evidence shows that arginine activates the mammalian target of rapamycin (mTOR) signaling pathway in the small intestine, integrating both intracellular and extracellular signals. It regulates gene transcription and protein synthesis, serving as a central regulator of cell metabolism, growth, proliferation and survival (LaPlante et al., 2009). Other nutrients, like omega 3 and omega 6 poly-unsaturated fatty acids (PUFA), are essential for countless metabolic functions. Both fatty acids are needed for an adequate immune system; however, increasing the n3/n6 ratio reduces the production of the inflammatory mediators interleukin 1-β and prostaglandin E2, which is favorable to the integrity of tight junctions on the intestinal epithelium (Shin et al., 2017). Dietary fiber (DF) stimulates the growth of beneficial intestinal bacteria, being fermented in the distal small intestine and large intestine with beneficial effects on the immune system. Microbial fermentation of DF results in the production of short-chain fatty acids (SCFA), branched-chain fatty acids (BCFA), lactate, amines, indoles, phenols, and gasses. In the absence of appropriate DF levels, proteolytic fermentation can take place in the colon, producing BCFA and potentially harmful metabolites like ammonia indoles, and phenols (Jha et al., 2019). BIOSECURITY IN FEED AND FARM Biosecurity practices in the feed to food chain are another fundamental tool to reduce AMR. Biosecurity helps to minimize the risk of entrance and transmission of microbial-associated pathogens, and therefore, reduces the need to use antimicrobials. • Feed Safety Heat treatment is a crucial processing step for feed hygiene management, preventing microorganisms from entering the feed to food chain. However, the efficacy of thermal treatment depends on the resistance of the contaminating agent and will not prevent further cross-contamination during
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