The use of medium chain fatty acids as alternatives to antibiotic use in pigs
By Wouter Naeyaert, Product Manager Pigs
Worldwide there is a clear demand to reduce the antibiotic use in livestock farming to reduce the risk for antibiotic resistance. Medium chain fatty acids are well known to exert excellent antimicrobial properties. For this reason they are used for a long time as alternative to antibiotics in piglet nutrition. However the properties of medium chain fatty acids go far beyond their antimicrobial effect. In this way they are an excellent option to reduce the antibiotic use in pigs.
Urgent time to act
The indiscriminate use of antibiotics in livestock production has been the subject of criticism by a lot of consumer organizations and governments. Consumers worldwide increasingly ask for healthy food from antibiotic-free raised animals. This as they want to preserve the ever-diminishing arsenal of effective antimicrobials in humans. If we don’t do anything, it is estimated that by 2050 yearly 10 million people will die due to antimicrobial resistance. This is far more than the actual number of deaths due to road traffic accidents or cancer!
There is a huge need for a transition from a preventive antibiotic use, to a responsible therapeutic use of antibiotics. To do this we need alternatives to reduce the antibiotic use in a responsible way, without compromising food safety and human health as well as animal health, welfare and productivity.
Improving gut health is the key
Maintaining a good gut health is essential to a low antibiotic use and good growth performances. As gut health is an extremely complex matter, no clear definition is available. However it is clear that gut health is an interaction between the diet, the gut mucosa and the gut microflora which should provide an effective digestion and absorption of the feed, the absence of gut diseases, a stable gut microbiota and an effective immune status.
The importance of a healthy gut cannot be underestimated. The gut surface is 200 times higher than the skin surface. And this surface has an extremely difficult and contradicting function: absorbing nutrients as efficient as possible, while reducing the entrance of noxious substances as much as possible. As the gut contains in fact 10 times more bacteria than the number of body cells, this is an extremely difficult task! In this way it is not strange that 20-35% of the energy- and amino acid requirements of the pig go to the gut. As 70% of the immune cells are concentrated around the gut, it is clear that gut health is also essential to improve immunity of the animals. The importance of gut health is also widely recognized in academical research. In 1999, 250 articles were published on gut health of pigs. Last year in 2015, this number increased to over 750 articles.
Taking all of this into account, it is clear that reducing antibiotic use is only possible by maintaining a good gut health. Of course gut health is difficult to measure, but an improved gut health can easily be seen in technical and health parameters. Examples are: improved growth performances, reduced FCR, less prevalence of pathogens (E. Coli, Brachyspira, Lawsonia, Salmonella), improved immunity, lower need for antibiotic use, and a lower mortality.
Medium Chain Fatty Acids as gut microbiota regulator
Medium chain fatty acids (MCFA) are saturated fatty acids consisting of aliphatic tails of total chain length of either 6 (caproic acid), 8 (caprylic acid), 10 (capric acid) or 12 (lauric acid) carbon atoms and a polar head. The use of free (so not coated, micro-encapsulated or esterified) MCFA as a functional feed ingredient is an effective way to reduce the antibiotic use in pigs. Free MCFA provide an early pathogen barrier in the stomach of the animal. This is an advantage over MCFA esterified mono, di- and triglycerides, which are only gradually active in the intestinal tract after endogenous lipase releases the free MCFA molecules
In the low pH environment of the stomach, un-dissociated MCFA are capable of penetrating the phospholipid bilayer of the bacterial cell membrane, thereby destabilizing it. This results in leaking of bacterial cell content on the one hand and entering of MCFA in the bacterial cells on the other hand. Inside the bacterial cell, MCFA’s encounter a near-neutral environment resulting in accumulation of dissociated MCFA molecules and protons in the bacterial cytoplasm. Dissociated MCFA’s will intercalate with the bacterial DNA, thereby inhibiting DNA replication and thus bacterial growth. Intracellular acidification and inhibition of DNA replication will eventually lead to killing of the bacterium. Thanks to their specific chemical properties, medium chain fatty acids have a much higher antimicrobial activity compared to other acids. MCFA clearly show lower minimal inhibitory concentrations (MIC) when compared to short chain and long chain fatty acids (Table 1).
Not only do these medium chain fatty acids kill pathogens, they also alter virulence of pathogens. Even at non-bactericidal concentrations, MCFA’s can have a dramatic effect on pathogen persistence. By reducing the virulence of bacterial pathogens like Clostridium and Salmonella, the outcome of disease is altered and intestinal and systemic colonization is reduced, as shown in scientific trials. The...
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