Organic acids, such as citric and sorbic acid, and pure plant-derived constituents, like monoterpens and aldehydes, have a long history of use in pig feeding as alternatives to antibiotic growth promoters, according to Ester Grilli of the University of Bologna in Italy and co-authors in the United States and United Kingdom.

However, they report in BMC Veterinary Research, that the effects of these compounds on the intestinal barrier function and inflammation have never been investigated.

The aim of their study was to assess the impact of a microencapsulated mixture of citric acid and sorbic acid (OA) and pure botanicals (thymol and vanillin; PB) on the intestinal integrity and functionality of weaned pigs and in vitro on Caco-2 cells.

In the first study, 20 piglets were divided in two groups and received either a basal diet or the basal diet supplemented with OA+PB (5g per kg) for two weeks post-weaning, at the end of which ileum and jejunum samples were collected for Ussing chambers analysis of trans-epithelial electrical resistance (TER), intermittent short-circuit current (I-SC) and dextran flux.

Scrapings of ileum mucosa were also collected for cytokine analysis (n=6).

In the second study, the team measured the effect of these compounds directly on TER and permeability of Caco-2 monolayers treated with either 0.2 or 1g per litre of OA+PB.

Pigs fed with OA+PB tended to have reduced I-SC in the ileum (P<0.07) and the ileal gene expression of IL-12, TGF-β and IL-6 was down-regulated.

In the in-vitro study on Caco-2 cells, TER was increased by the supplementation 0.2g per litre at four, six and 14 days of the experiment, whereas 1g per litre increased TER at 10 and 12 days of treatment (P<0.05).

Dextran flux was not significantly affected though a decrease was observed at seven and 14 days (P<0.10 and P<0.09, respectively).

Overall, concluded Grilli and co-authors, OA+PB improved the maturation of the intestinal mucosa by modulating the local and systemic inflammatory pressure, ultimately resulting in a less permeable intestine, and eventually improving the growth of piglets prematurely weaned.

Reference

Grilli E., B. Tugnoli, J.L. Passey, C.H. Stahl, A. Piva and A.J. Moeser. 2015. Impact of dietary organic acids and botanicals on intestinal integrity and inflammation in weaned pigs. BMC Veterinary Research. 11:96. doi:10.1186/s12917-015-0410-0

Further Reading

You can view the full report (as a provisional PDF) by clicking here.

May 2015