For a long time, antibiotics have been prophylactically used to overcome the influence of microbial imbalances and make piglets less sensitive for potential pathogens.

Nowadays, however, there is worldwide increasing pressure of regulations to reduce prophylactic as well as curative usage of antibiotics in farm animals. Microbial regulators – natural, moreover synergistically combined ingredients - are the most recently available alternatives of a step-by-step solution.

Weaning dip – the foreseeable peril

Furthermore, high productivity requires an optimal intestinal health and immunity as production animals are pushed to their physical limits. Consequently, even the slightest intestinal imbalance can compromise top production. The weaning dip has been well researched and documented and as such can also be described as piglets being m5ore vulnerable for pathogens due to a lack of feed intake.

The absence of feed in a piglet"s gut system results in a microbial imbalance, leading to higher occurrences of diseases. Thus, this short weaning phase in a pig"s life can have far-reaching consequences, negatively affecting the pig"s entire rearing period (see Figure 1). Strengthening the microbial gut flora and increasing feed intake includes the addition of medium-chain glycerides and essential oils, well balancing the intestinal microbial community and immune reactions, meanwhile enhancing proliferation of enterocytes. Such microbial regulators support piglets to maintain a healthier status, last but not least for better performance effects.

Medium-chain glycerides (MCGs) – The highly effective antibacterial compound

Medium-chain fatty acids are known to have an effect on bacterial growth. However, not all medium-chain fatty acids have the same effect, as some bacteria are sensitive to specific chain lengths of fatty acids. Caproic acid (C6:0) for instance, has a relatively strong effect against E. coli and salmonella strains – more than most other medium-chain fatty acids.

In combination with caprylic acid (C8:0 E. coli and salmonella are targeted. It has been shown that medium-chain fatty acids have a better microbial regulatory effect, reflected in their lower minimum inhibitory concentration (MIC) values than other organic acids.

Moreover, they target a broader spectrum of bacteria (both gram-positive and gram-negative bacteria). Besides their acidic function, some medium-chain fatty acids, like caproic acid have lipophilic properties that they can dissolve in fats.

That way, they can disrupt cell membranes of pathogenic micro-organisms. When used in piglet feed, it is important to get the medium-chain fatty acids right there in the digestive system where they will be most effective. By esterifying the medium-chain fatty acids using glycerol they can be bound in glyceride molecules.

Lipases synthesised in mouth, stomach and gut will work on the esterified medium-chain fatty acids, respectively medium-chain glycerides, ensuring a gradual release (lipolysis) as opposed to free medium-chain fatty acid (MCFAs) products. Because of their "slow-release" effect they will be effective in the stomach and continuing on in the digestive tract. The maximum release and efficacy will be in the small intestine.

Besides the antimicrobial effect, medium-chain glycerides support the gut health (larger villi and smaller crypt depths; see Figure 3). This positive influence on gut health leads to enhanced uptake and use of nutrients. Medium-chain glycerides are also known to have a positive modulating effect on the immune system. If the immune system is less stressed, it needs less energy and amino acids for its maintenance, which implies that more nutrients become available for the growth of the animal. The efficacy of this strategy has been proven in both in vitro and in vivo trials.

Phytogenic components (PCs) – The most effective natural antimicrobial

PCs (trivially named essential oils) made from herbs and spices, have a long tradition as aromas in human food. These phytogenic substances also have a place in medicine and are known for their wholesome effects. Aromatic compounds of oregano, thyme and chili pepper in a phytogenic mixture, have been shown a positive influence on several physiological processes in the animal.

PCs are also known to contribute to a balanced microbial gut flora. Extracts stimulating the production of digestive enzymes, enhancing digestion and absorption of nutrients have been documented. They also have an anti-oxidative function.

The antimicrobial action of phytogenic components is twofold. Small hydrophobic active compounds will be absorbed by the cell membrane of pathogenic cells resulting in a higher permeable membrane through which the cell contents will leak out. In reverse, other antimicrobial components of the phytogenic blend will be able to enter the cell. There they will interfere with the bacterial growth. The PCs can be combined to become antibacterial for both gram-positive as gram-negative bacteria, affecting E. coli, salmonella, clostridia but also eimeria types.

Encapsulating a blend of selected phytogenic components in a vegetable fat matrix, the formulation provides stability during the production process. A side-effect is that, just like in the previous paragraph, the matrix will ensure a slow release effect throughout the piglet"s digestive tract. In addition, it will remain active at high intestinal pH. It has been shown that addition to piglet feed lowers animal mortality and improves animal performance, like FCR and growth.

In combination, medium-chain glycerides and phytogenic blends can complement each other – and even be synergistic, i.e. the spectrum of activity is broader than the sum of its parts. Both active components disrupt the cell membrane integrity of pathogenic bacteria through different places of interaction, because of the difference in hydrophobicity, molecule size and charge. The interaction of these molecules will enhance their effect and will provide each other with easier access to the cytoplasm. In addition, lower dosage rates are needed.

AveMix® Plus combines and augments antimicrobial effects of these ingredients. Decrease in animal mortality is documented, as well as an increase in their feed intake.

by AVEVE Biochem, Belgium

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