The reductions and ultimately ban of (in-feed) antibiotics from animal feed does not come without its challenges. An overall approach to cope with these challenges imposes itself: persevered farm management, good hygienic practices and extra balanced nutritional feed composition (e.g. banning excessive protein levels whilst maintaining digestible amino acid-level, ensuring appropriate energy levels) are essential steps in the quest for antibiotic-free feeds.

Another worthy step to consider is non-antibiotic in-feed specialties. Medium-Chain (MC) products and phytogenics are known to be very promising in this context. Literature and trials have shown beneficial effects in the animal itself as well as on the microbiota present in their gut. So, a double manner to assist birds to extra cope with the above-mentioned difficulties.

Medium-Chain Glycerides versus pathogens

Medium-Chain Glycerides (MCG"s) consist of medium-chain fatty acids esterified with glycerol. The medium-chain fatty acids provide the activity of the product. Binding them to glycerol, will get the MCFA"s to be slowly released (by lipases) throughout the GIT. This ensures the product to be active at the place of greatest impact: the small intestine.

Medium-chain products have a greater antimicrobial effect than short chain fatty acids and long chain fatty acids. Especially towards Gram(-) bacteria. The chain length determines the antibacterial effectivity towards specific bacteria. For example caproic acid (C6) is more active towards E. coli compared to capric acid (C10).

Along their direct antibacterial effect, medium-chain fatty acids decrease virulence gene expression of Salmonella and thus decrease invasion in intestinal epithelial cells in broilers, even at sub inhibitory level.

Reduced level of colonisation of ceca and internal organs of broilers in a Salmonella Enteriditis challenge, has been validated. Similarly an in vivo-study reported that medium-chain products can reduce early Salmonella colonisation in turkeys.

Supplementing C8 to feed for 10-day old broiler chicks, orally challenged with Campylobacter jejuni reported reduced caecal Campylobacter content in the C8-feed.

Besides effect on microbiota, gut morphology effect of in-feed MC products has been documented: increased villus to crypth ratio"s in the small intestine. Increased V/C favours digestibility and absorptive capacity of the small intestine. Caproic and Caprylic acid are even reported to meet the energy requirements of colonic epithelial cells in vivo as well as butyrate, which is commonly acknowledged for this.

MCG"s are compatible with other bioactive products, like phytogenic compounds. Amongst other effects, carvacrol and thymol are reported to improve intestinal integrity and modulating immune responses in Clostridium perfringens challenged broiler chicks. Their destructive effect on chicken Eimeria oocysts is published. The mechanism of the direct antibacterial effect of these components are inline with the mechanism of medium-chain compounds.

Improved performance at Belgian farm trials with boosted MCG"s

Medium chain glycerides upgraded with aromatic compounds, called "AveMix Plus" was tested in several farm trials by AVEVE.

In Belgian farms the concept was tested on top of a standard commercial control feed, see Figure 1. The birds fed the combination concept needed less feed to obtain similar growth rate compared to the control feed. A lower mortality percentage was registered for the Plus fed birds.

AveMix Plus, AGP free feed worthy

All observed effects above, indicate a more optimal use of energy supplied by the feed upon AveMix Plus addition to the feed, giving them more "room" for growth. More efficient use, read "more economical" use of animal feed, the end goal every farmer pursues.


by Goedele Buyens, AVEVE Biochem NV

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