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Microbial Throwbacks Short-chain Fatty Acids and The Animal Intestine

Short-chain fatty acid

Some people think that the material life of the microcosm is short and insignificant. In fact, microorganisms are so diverse and numerous that their simple structures often have complex forms and sophisticated functions, and they have the ability to affect the whole body in an individual organ.
The gut provides a habitat for microorganisms, and short-chain fatty acids, which are metabolites of microorganisms, maintain the intestinal barrier function, so it is clear that microorganisms also know how to return the favor!


Animal gut microbes and their metabolites affect not only the development of the host mucosal immune system, angiogenesis, repair and renewal of the intestinal epithelium, and maintenance of intestinal function, but also the expression of host genes and the regulation of lipid metabolism.

How are short-chain fatty acids produced?

Anaerobic bacteria in the colon produce short-chain fatty acids during the fermentation of nutrients such as starches, starch-like and non-starch polysaccharides (NSP, the main component of dietary fiber). Also, short-chain fatty acids can be produced naturally by the body’s metabolism, especially in the liver.

Short-chain fatty acids consist mainly of acetic acid, propionic acid, and butyric acid, which account for about 90% to 95% of the total. Acetic acid is a product of fermentation by a variety of bacteria, propionic acid is a major metabolite of fermentation by Anabaena, and butyric acid is a major metabolite of the phylum Bacillus thickeniensis. Some intestinal microorganisms synthesize butyric acid by using lactic acid and acetic acid at the same time, thereby preventing the accumulation of lactic acid and maintaining the intestinal environment.

How are short-chain fatty acids produced


Just as there is no single bacterium that can break down all nutrient substrates, there exists no bacterium that can produce all three short-chain fatty acids at the same time after fermenting carbohydrates.


How do short-chain fatty acids regulate intestinal barrier function?

Intestinal barriers help the body to resist invasion by foreign pathogens and include mainly mechanical, microbial, chemical and immune barriers.

The mechanisms of action of short-chain fatty acids on the four intestinal barriers, in particular the improvement of the gut microbiota and IEC via G protein-coupled receptor (GPCR)-mediated immune pathways and histone deacetylase inhibitors (HDACI), are of great significance for precision nutrition.

1.Mechanical barriers

The intestinal mucosal mechanical barrier consists of the IEC, tight junctions between epithelial cells, and a mucus layer covering the surface of the IEC.

Short-chain fatty acids reduce intestinal permeability and improve the mechanical barrier function of animal intestines mainly by promoting the expression of intestinal tight junction proteins claudin, occludin and ZO-related genes.

Mechanical barriers in the animal intestine

2.Microbial barrier

Short-chain fatty acids inhibit the growth of harmful intestinal bacteria mainly by releasing hydrogen ions, lowering intestinal pH, competing for energy, forming antimicrobial peptides, and blocking the biosynthesis of harmful bacteria to achieve microecological balance.

3.Chemical barrier

The intestinal chemical barrier consists mainly of a mucus layer covering the IEC. Intestinal microorganisms, host inflammatory mediators and intestinal secretions (gastric acid, glycoproteins, digestive enzymes, etc.) may affect the intestinal chemical barrier.

Short-chain fatty acids regulate the chemical barrier mainly by promoting the expression of MUC (mucin)-related genes, triggering the secretion of defensins by Pan cells, decreasing the apoptotic index of intestinal cells, and increasing the enzymatic activity of intestinal secretions. In addition, short-chain fatty acids regulate the chemical barrier through multiple signaling pathways MUC-related genes regulate the chemical barrier.

Animal intestinal chemical barrier

4.Immune barrier

The intestinal immune barrier consists mainly of intestinal-associated lymphocyte tissue and diffuse immune cells. Short-chain fatty acids are recognized to modulate the intestinal mucosal immune response by regulating the function of intestinal mucosal immune and non-immune cells affecting cell differentiation, recruitment and apoptosis.

In addition, short-chain fatty acids modulate the immune barrier by activating cellular receptors leading to cell proliferation or differentiation, and by acting as histone deacetylase inhibitors.

In summary, short-chain fatty acids are important regulators of intestinal health and immune function.

There are three ways to supplement short-chain fatty acids in the animal body, one is to decompose carbohydrates through colonization of beneficial bacteria, but the hindgut of poultry is limited in volume and the bacteria are unstable in high-temperature processing; the second is to supplement dietary fibers in the diet, but it is easy to cause excessive intestinal burden to the animal pups; and the third is to add short-chain fatty acids directly in the diet, which is more direct and efficient than the previous two ways.

Calid butyric acid glyceride series

Monobutyrin, tributyrin and other butyric acid glyceride series products produced by Calid can effectively supplement the short-chain fatty acids that are in short supply in animal diets, improve the function of animal intestinal barriers, defend the health of intestinal tracts, and improve the growth performance of animals.

About Us

Calid Biotech (Wuhan) Co., Ltd. is a specialized company that focuses on the R&D, manufacturing, promoting, and application of new technologies and products for animal lipid nutrition, providing solutions for the feed-grade fatty acid balancing to customers in the livestock and fishery field.

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