Effects of avilamycin and essential oils on mRNA expression of apoptotic and inflammatory markers and gut morphology of piglets

In this study 120 piglets were allotted to 3 dietary treatments, negative control group, one group receiving a blend of essential oils (EO) derived from oregano, anise and citrus peels (40 mg/kg diet), and a positive control group treated with avilamycin as growth promoting feed additive (40 mg/kg diet). On day 22 of the experiment, 12 representative animals from each treatment group were sacrificed and tissue samples were collected for quantitative real time-PCR analysis and gut tissue morphology. EO and avilamycin decreased the gene expression of the transcriptional factor NF kappa B and the apoptotic marker TNF alpha significantly in the ileum and jejunum, respectively. The expression of the proliferation marker Cyclin D1 was also significantly decreased by both substances in the colon, mesenteric lymph nodes and spleen. The colonic crypt depth was reduced by avilamycin, and also numerically by the essential oils. These changes correlated with the up-regulation of the apoptosis factor Caspase 3. Histomorphometry revealed a smaller size of ileal Peyer's patches through the use of both feed additives, which correlated significantly with lower expression rates of NF kappa B. In conclusion, the results suggest that EO and avilamycin relieved weaning piglets from an immune defence stress in a similar way.