<i>In vitro</i> and <i>in vivo</i> antimicrobial activity of cinnamaldehyde and derivatives towards the intestinal bacteria of the weaned piglet

Cinnamaldehyde has an effective antimicrobial activity and therefore it received interest as a feed additive in swine nutrition. However, its high reactivity to amino acid residues might affect efficacy digestive processes. As alternative, 20 chemical derivatives were evaluated. The vitro activities tested fermentation model. Thereof three compounds selected fed newly weaned piglets. Five dietary treatments replicated six pens of four pigs per pen; i.e. control, cinnamaldehyde at 100 400 mg/kg, 2-methoxycinnamaldehyde 4-methoxycinnamaldehyde, both equimolar mg/kg cinnamaldehyde. In results showed that 4-nitrocinnamaldehyde the highest activity; however, this compound is carcinogenic was not further issued. had second-highest activity, particularly against coliform bacteria Escherichia coli (E. coli), followed by hydrocinnamaldehyde. All other lower potency, but they consistently more bactericidal E. compared Gram-positive bacteria. At pH 7, aldehydes stronger than their corresponding carboxylic acids, which case 5, suggesting different mode action. vivo trial, no significant improvements animal performance or effects observed. To conclude, apart from 4-nitrocinnamaldehyde, none higher potency Three trials failed demonstrate major positive outcomes trial.Highlights4-Nitrocinnamaldehyde vitro.Cinnamaldehyde 2-methoxycinnamaldehyde.No