Butyric acid and gut health

Gut health has a direct impact on animal performance. Although there is no clear definition for gut health, in most of the cases experts refer to different functions including:

• nutrient digestion and adsorption
• stable microbiome
• optimal barrier function (development of the mucus layer and epithelial cell integrity)
• absence of diseases and infections
• effective immune system
• general well-being

1. Directly impacting the epithelial function by providing energy to epithelial cells, supporting electrolyte transport, and regulating pH
2. Promoting mucus production and hence supporting the stability of the barrier between epithelial cells and the outside
3. Impacting the intestinal barrier function by supporting epithelial cell integrity, reducing permeability, and promoting tight junction expression
4. Positively affecting mucosal immune function
5. Inducing expression of antimicrobial proteins (defensins and cathelicidins)
6. Affecting the enteric nervous system with an apparent impact on the motility of the epithelial cells

• A positive impact on the immune function of the animals
• Increased epithelial cell function
• A reduction of pathogen counts
• An overall positive effect all along the gastrointestinal tract as described in recent reviews on the use of butyric acid in poultry production

The use of butyric acid in poultry production is well-established and its effects on performance are well-known, but could its effects be improved even more?

Valeric acid: a missing piece?

Even though valeric, isovaleric and 2-methylbutyric acid are also produced in the gastrointestinal tract by the microbiota, they have not been nearly as well researched as some of their SCFA and branched fatty acid peers. Among these acids, valeric acid has been gaining attention, especially for human medicine. Research into the role of valeric acid in gut health and health in general is ongoing, but thanks to in vitro studies, studies in mice, and epidemiological observations we know for example that valeric acid can prevent inflammation as well as maintain gut integrity. Low levels of valeric acid in humans have been linked with different diseases such as neurodermitis in children. Additionally, valeric acid has been particularly investigated because of its property as a histone deacetylases inhibitor (HDI). HDIs are used in psychiatry and neurology but are gaining more and more interest for the treatment of cancers, parasite infections and inflammatory diseases.
Valeric acid (in its esterified form) has been shown to exert positive results in poultry production. The intestinal structure of broilers improves, increasing GLP-2 production which is considered to play an important role in promoting intestinal growth and enhancing intestinal function, resulting in better performance. Another study reported the beneficial effect of valeric acid on reducing the impact (lesion scoring and mortality) of a Clostridium perfringens challenge, maintaining a good performance level when compared to esterified butyric acid. 

Utilizing synergies to improve performance

In a trial performed in Spain (IMASDE) using 792 male broiler chickens (Ross 308 DOC, 12 replicate pens per treatment and 22 birds per pen) the effects of a product combining valeric acid and butyric acid in esterified form (Gastrivix™ Avi) were compared to using sole tributyrins and a control group without any feed additive used. Gastrivix™ Avi significantly improved final body weight, average daily gain (ADG) and feed conversion ratio (FCR) compared to the control group by 7.1%, 7.4% and 8 pts, respectively. Gastrivix™ Avi numerically improved final body weight and ADG, and statistically improved FCR by 3.8%, 3.9% and 6 pts compared to the tributyrins only group (Table 1). Both numerical and statistical improvements were reported for the Gastrivix™ Avi group compared to both the control group and the tributyrins group in each single feeding phase. 
In this trial Gastrivix™ Avi proved to be an excellent feed additive to improve the performance of broilers. Additionally, the data suggests that combining esters of butyric acid with esters of valeric acid (Gastrivix™ Avi) shows beneficial effects compared to the use of sole esters of butyric acid when used for the purpose of improving broiler performance.

Table 1. Performance results from a trial in broilers (Ross 308 DOC) performed in Spain (IMASDE) in 2021

The use of Gastrivix™ Avi shows consistent improvements in performance in terms of body weight and FCR (displayed in Figure 1) over all the scientific and semi-scientific trials run so far with the product. The average improvement over the eight trials is 4 points in FCR resulting in a good return on investment for the product and hence an economic benefit. As all producers are currently faced with increasing production prices, Gastrivix™ Avi can be a tool to rely on to support gut integrity and performance.

Figure 1. Improvement of FCR in broilers fed diets containing Gastrivix™ Avi compared to a control group fed a diet containing no additives. The trials were run by Perstorp in cooperation with different partners between 2019 and 2021

References are available on request