Written by Romain D’Inca, Category Specialist MCFA at Agrifirm

Medium-chain fatty acids (MCFAs) are saturated, unbranched monocarboxylic acids with a carbon chain length between 6 (C6) and 12 (C12) atoms. They are proven since many years to exert antibacterial actions toward both gram-positive and gram-negative, especially when used in blends. Consequently, MCFAs are part of the strategy to improve naturally performances and health of piglets around weaning. More recently, antiviral action of MCFAs against enveloped viruses have been proven, extending the potential direct and targeted applications in animal production, globally.

In the meantime, animal nutrition and health sector progressed tremendously. During the last two decades, quality of raw materials, precise nutrition, progressive reduction in the use of chemicals (antibiotic growth promoters, pharmacological dosages of Zinc Oxide, …) and increased farm biosecurity altogether reduced animals’ exposure to many risk factors, optimizing general performances. The use of MCFAs has been found to be associated with improvements in various zootechnical parameters in pigs, such as growth and feed efficiency, even in the absence of specific challenges. For example, incorporating MCFAs in feed is linked to a reduced occurrence of respiratory issues, despite the fatty acids not directly interacting with the respiratory tract. This suggests a broader and more systemic role of MCFAs in animals.

MCFAs can trigger more than local and direct actions

Despite less documented, recent studies suggest that fatty acids also act as signaling molecules via specific subsets of G-protein coupled receptors (GPRs), the largest and most diverse group of membrane receptors in eukaryotes. Some of those receptors belong to the free fatty acid receptors (FFARs) family and show variable selectivity. While FFAR1 (GPR40) is activated by all known MCFAs, FFAR2 (GPR43) and FFAR3 (GPR41) have a preference for C6 and GPR84 for C9-C12. The latter one, GPR84, has only be suspected to be activated by MCFAs in 2020, despite being known for more than 20 years. Stimulating these receptors trigger a cascade of complex cellular events. Of particular interest, GPRs show ubiquitous expression in various cell types, including epithelial and immune cells (Figure 1).

Synthetic view on the role of GPR84 in immune cells, MCFAs from C9 to C12 being a major ligand
Figure 1: Synthetic view on the role of GPR84 in immune cells, MCFAs from C9 to C12 being a major ligand.

On that regards, digestive tract of animals is an ideal example, combining a broad surface of contact through enterocytes’ epithelium layer and is in the mean time, the largest immune organ of the body. It is therefore an excellent organ to also investigate the indirect role of MCFAs on non-specific and systemic immune responses. In young pigs, apart from severe dysbiosis, small intestine epithelium is frequently in contact with bacterial LPS, even in non pathogenic amounts. The LPS-induced low-grade inflammation will attract neutrophils (phagocytic white blood cells) locally by a chemiotactism phenomenon. It means that MCFAs provided in the feed will interact not only with the GPRs of the enterocytes but also those of the neutrophils, possibly cascading molecular signalling also in that white blood cells. Our recent studies in pigs confirmed that feeding MCFAs to pigs was effectively able to increase neutrophils’ viability. Despite additional studies are required to specifically point out the balanced role of the different GPRs on that response, it represents one step further in the understanding of the systemic role of MCFAs.

Immune benefits of MCFA are of interest for the progeny too

When it comes to the topic of indirect immune stimulation in pigs, sow’s pregnancy comes along naturally in mind. Because the epitheliochorial type of placenta in pigs do not permit the passage of antibodies during gestation, immunoglobulins (Ig) cannot be shared before birth with the developing embryos. Newborn pigs are therefore born agammaglobulemic and unable to mount rapid immune responses at systemic and mucosal levels without direct supply of maternal immunity via colostrum (IgG) and milk (IgA). Stimulating the production of immunoglobulins in the mammary gland of sows maximizes the chance for each piglet to get sufficient amounts of Ig, increasing their capacities to face stressors and reach weaning in a better status. Can a specifically-designed blend of MCFA stimulates immune system of sows enough to increase the Ig production and secretion via the mammary gland?

We investigated that hypothesis using a blend of MCFAs developed for sows in a high-performing SPF farm in Europe. A total of 400 sows were supplemented from the beginning of gestation to the end of lactation at 21 days, where piglets were weaned. Performances were compared with data from the 3 months before introduction of the MCFAs. Among several parameters under investigations, IgG levels in the colostrum were measured using immunocrit levels (%). We especially focused on gilts and sows with parity >4, as they represent specific populations of animals with higher needs for immune support. The use of MCFAs increased the immunocrit levels by an average +60%, difference being +36% for sows with parity >4 and up to +103% for gilts (Figure 2).

Immunocrit levels (%) in the colostrum of sows receiving (MCFA) or not (Control) a specific blend of MCFAs during the whole gestation and lactation period
Figure 2: Immunocrit levels (%) in the colostrum of sows receiving (MCFA) or not (Control) a specific blend of
MCFAs during the whole gestation and lactation period.

These differences were associated to an improvement of zootechnical parameters such as 17% reduction in pre-weaning mortality and +1.32 piglet/sows/year, confirming the known protective role of IgG in piglets.

Conclusion

Despite permanently improving nutrition and health conditions, modern pig rearing systems still expose piglets to various non-specific stressors which silently penalizes performance. The immune stimulation properties of Medium-chain fatty acids and their demonstrated capacity to improve immune supply from sows to newborn piglets deserve a growing interest to support naturally animals’ resilience until weaning.

References are available on request.

Contact your agrimprove expert

Marc Intven
Sales Manager