Medium-chain fatty acids (MCFAs) are widely
implemented nowadays because of their beneficial effects on general health and performance. Yet, according to scientific research, the alpha-
monoglycerides of these MCFAs are much more powerful in their antibacterial effect.
Nutritionists are increasingly including MCFAs in their feed formulations. It is known that medium-chain fatty acids are efficiently absorbed and metabolised, thus serving as a good energy source for the animal. In addition, MCFAs have inhibitory effects on pathogenic pressure in the gut. Yet as far back as 1972, it was discovered that monoglycerides are more active against pathogens than their free fatty acids. An additive* (hereafter called the 'additive') has been developed to effectively inhibit the pathogenic pressure exerted by pathogenic, gram-positive bacteria (e.g. Streptococcus sp.) and fat-enveloped viruses (e.g. arterivirus causing PRRS). The main ingredient is alpha-monolaurin. Alpha-monolaurin is a fat-like, heat-stable molecule produced by the esterification of lauric acid and glycerol. Due to the chemical characteristics of alpha-monolaurin, the molecule is pH independent and will not dissociate in the intestinal tract (pH around 6-6.5). Moreover, alpha-monolaurin can be absorbed into the lymphatic system and bloodstream. The antimicrobial activity of alpha-monolaurin against gram-positive bacteria has been described in literature and investigated by the developers of this additive. Monoglycerides have been shown to have stronger antibacterial effects than their free fatty acids. In the field, it has been shown that it is possible to suppress infections with Streptococcus at pig farms when the preventive use of Amoxicillin is replaced by this additive. The developers of this additive usually replace the preventive use of Amoxicillin with FRA C 12 early on in the lactation feed at a dose level of 2 kg/tonne of feed, followed by 4 kg/tonne of prestarter feed and 2-3 kg/tonne of starter feed.
Case study: Fighting PRRS
One of the main challenges in swine reproduction worldwide since the 1980s has been porcine reproductive and respiratory syndrome (PRRS). The fat-enveloped virus causing PRRS is particularly present in the respiratory tract and negatively influences the overall immunity of the pig via both horizontal and vertical transmission. In order to reduce the negative effects related to PRRS and secondary bacterial infections such as Streptococcus suis, the additive can be effective when it is added to the sow’s diet 1-2 weeks before farrowing and the lactation feed. Through the systemic mode of action, the active ingredients are transferred from the sow to their offspring via the milk of the sow, leading to health improvements in both the sow and the piglet. The additive was used at a commercial farm in Southern Europe that was contiminated by PRRS. In the case study, a treatment group and control group were observed. The sows in the treatment group were fed 15 g of the additive per day, starting seven days pre-farrowing until next service. The only difference between the control and treatment feeds was the addition of the additive. Total trial duration was approximately 35-40 days. The results are shown in Table 1 and clearly show the beneficial effects of the additive on both the piglet's health and the sow's reproductive performances.
Systemic mode of action
Another trial was performed at a fattening pig farm in the Netherlands. The treatment animals received 10 grammes of the additive per animal per day on top of their basal diet, whereas the control animals received the basal diet without the addition of the additive. Both groups consisted of nine animals. Blood samples were taken at the start (day 0) and the end of the trial (day 14). For practical reasons, the blood samples of the control and treatment groups were pooled to make three treatment blood samples and three control blood samples.
The results (Table 2) support the suggested systemic mode of action of alpha-monolaurin. Based on literature, the active ingredient of the additive was expected to be partially transported to the systemic circulation via the intestinal lymphatic transport system. In this way, alpha-monolaurin would be protected from first-pass hepatic metabolism. This means that alpha-monolaurin will not be transported via the hepatic portal vein to the liver, but enter the blood via the lymphatic system. Hence, alpha-monolaurin is able to conduct its antibacterial and antiviral effects before it is broken down by the liver.
Alpha-monolaurin has proved to have strong antiviral and antibacterial effects. This paves the way for its use as a new generation of non-antibiotic products to improve livestock health and general performance. The benefits of the additive mentioned herein will be explored more in the near future.