Articles / Films
The potential of butyric acid in livestock
Since the European Union's complete ban on the use of antibiotic growth promoters (AGPs) in animal feed, which came into force in January 2006, the development of alternative strategies to maximise the genetic potential of animals in commercial production has become a prominent area of scientific interest. One such approach involves the use of biologically active substances, including lipid-based components. Dietary fat serves not only as an energy source but is also rich in substances that regulate numerous essential physiological processes. Various forms of fatty acids have attracted considerable interest for their health-promoting properties, among them butyric acid (BA).
CHARACTERISTICS OF BUTYRIC ACID
Butyric acid (BA) is an organic carboxylic acid with a strong, unpleasant odour reminiscent of rancid butter. It is classified as a short-chain fatty acid (SCFA; C4). Under natural conditions, it is produced in the intestines of mammals and birds during anaerobic bacterial fermentation of dietary fibre. Synthesised in the large intestine, it constitutes a primary energy substrate for intestinal epithelial cells (colonocytes), supporting their proliferation, regeneration, and reinforcement of the intestinal barrier.
Free butyric acid is readily absorbed and utilised predominantly in the upper gastrointestinal tract. To enhance its functional value, it is frequently supplemented in various forms designed, among other purposes, to ensure stability, improve organoleptic properties, and facilitate delivery to the distal segments of the gastrointestinal tract. The most widely used forms include esterification with glycerol — yielding glycerol esters of butyric acid — sodium and calcium salts (sodium or potassium butyrate), and encapsulation in lipid carriers. Numerous scientific studies have confirmed the rationale for using these preparations, as they contribute to enhanced resistance to pathogens, strengthened intestinal barrier integrity, improved gastrointestinal epithelial morphology, and modulation of the immune response.
EFFECTS ON INTESTINAL MORPHOLOGY AND INTEGRITY
The intestinal epithelium is a structure sensitive to both exogenous and endogenous factors that may cause damage and increased permeability. It plays a critical role in the absorption of nutrients while simultaneously serving as a key component of the intestinal barrier, protecting the organism against the invasion of pathogens and toxins. Impaired intestinal barrier integrity may lead to the development of inflammatory conditions, malabsorption of nutrients, and immune system dysfunction. Maintaining good gut health is therefore of paramount importance.
Numerous studies conducted in poultry and swine flocks have demonstrated a positive effect of various forms of butyric acid on small intestinal morphology. A significant improvement in the villus height-to-crypt depth ratio in enterocytes has been observed, along with an increase in the absorptive surface area of intestinal epithelial cells. Supplementation with various forms of BA stimulates regeneration of intestinal epithelial cells and increases mucosal thickness. This effect may be attributed to the stimulation of gastrointestinal hormone secretion, enterocyte proliferation-inducing peptides, and increased mucosal blood flow. Moreover, BA serves as an excellent energy substrate for intestinal cells.
It has also been demonstrated that sodium butyrate stimulates the formation of tight junctions between intestinal cells via activation of key intracellular signalling pathways — in particular the AMP-activated protein kinase (AMPK) pathway — thereby enhancing the expression of tight junction proteins such as claudin, occludin, and ZO-1 (zonula occludens-1), which are responsible for reinforcing the intestinal barrier.
IMMUNOMODULATORY EFFECTS
Supplementation with butyric acid in its various forms has been shown to improve immunological function in both poultry and swine nutrition. It has been demonstrated to stimulate the proliferation and differentiation of immune cells. In studies conducted in swine, elevated levels of secretory immunoglobulin A (IgA) in the intestinal mucosa and increased serum IgG concentrations were observed. In another study, BA supplementation increased thymus weight and antibody titres, resulting in enhanced resistance of broilers to Newcastle disease infection.
ANTIBACTERIAL EFFECT
Butyric acid exhibits antibacterial properties. Under appropriate conditions within the gastric and intestinal environment, it undergoes dissociation, releasing hydrogen ions that acidify the luminal milieu. Maintaining a low pH within the gastrointestinal lumen stimulates the secretion of digestive enzymes and creates an environment unfavourable to the proliferation of pathogenic microorganisms, while simultaneously promoting the colonisation of beneficial microbiota, particularly bacteria of the genera Bifidobacterium and Lactobacillus.
EFFECTS ON DIGESTIBILITY AND PRODUCTION PERFORMANCE
The properties of butyric acid and its various forms described above may have a significant positive impact on production performance. The processes of digestion and nutrient absorption are closely associated with intestinal health, and more specifically with the absorptive surface area of the gut. The elongation of intestinal villi and deepening of crypts induced by butyric acid may contribute to more efficient feed utilisation. Numerous studies have confirmed the efficacy of BA supplementation in improving the feed conversion ratio (FCR) and protein digestibility, through enhanced secretion of digestive enzymes and an overall improvement in gastrointestinal tract health.
FARM-LEVEL APPLICATION
Currently, the market offers various forms of butyric acid suitable for incorporation into feed in dry (powder/granule) or liquid form — e.g., as glycerides. BA is very frequently used in combination with other active substances, such as caprylic acid, capric acid, or lauric acid, enabling a synergistic effect and enhanced antibacterial activity. The use of such combinations often produces additive effects or simply broadens the functional profile of the product. One example is the additional incorporation of herbs, vitamins, and minerals that support gastrointestinal and immune system function.
Butyric acid — including in combination with other active substances — is particularly valuable during convalescence following infectious diseases and enteric disorders, given its favourable influence on regenerative processes. It may also support the gastrointestinal tract during dietary transitions or in preparation for critical stages of the production cycle, such as weaning in piglets. The latter application has been well documented in the literature, frequently with positive outcomes from the use of so-called butyrates.