Lawsonia intracellularis cause proliferative enteropathy (PE), an economically important swine disease with global distribution. Frequently, control of PE includes antimicrobial therapy and vaccination with an attenuated live vaccine. However, the use of antibiotics leads to possible development of antimicrobial resistance in humans and animals. Therefore, it is important to provide alternative methods of PE control. Phytogenic feed additives are proposed as an alternative to control of bacterial diarrhea in animals. Hence, the aim of this research was to assess if a phytogenic additive (essential oil blend of Thymus vulgaris, Origanum vulgare and Coriandrum sp. and a plant extract of Castanea sativa, lysozyme and nicotinamide) may replace antibiotics in the control of PE in 144 weaned piglets (72 fed with the phytogenic blend and 72 controls) naturally infected with L. intracellularis. The quantity of L. intracellularis faecal shedding was monitored by real-time polymerase chain reaction (PCR) assay in faecal samples on day 0, 14 and 28, whilst the level of the ileum damage was determined by immunohistochemistry (IHC) assay and performed on gut sections.
Real-time PCR revealed that cycle-threshold (Ct) values in the treatment group increased significantly over time and were higher than in the control. These results indicate that the use of the phytogenic additive decreases the faecal excretion of L. intracellularis both throughout the experiment and in comparison to the control. The expression of the L. intracellularis antigen in IHC assay was lower in animals under the phytogenic additive, implying that the additive leads to the decrease in the pathogen quantity in the ileum. Significantly higher feed conversion ratio was recorded in the treatment group.
According to the present results it might be concluded that the phytogenic additive may be beneficial in the control of PE, but additional research is necessary to assess its use in various pig categories and define the optimum concentrations.
Draskovic, V., Bosnjak-Neumuller, J., Vasiljevic, M., Petrujkic, B., Aleksic, N., Kukolj, V., and Stanimirovic, Z. 2018. Influence of phytogenic feed additive on Lawsonia intracellularis infection in pigs. Preventive Veterinary Medicine. 151, 46-51. https://doi.org/10.1016/j.prevetmed.2018.01.002