Thinking Outside the Box – The Use of Plant Compounds as Natural Anthelmintics

Dr. Brady Campbell, Assistant Professor, State Small Ruminant Extension Specialist

(Image Source: Hoste et al., 2012)

By now, most producers should be aware that as of June 11th, all over-the-counter antibiotics will require a veterinarian prescription. Although anthelmintic or de-worming products are not classified as an antibiotic and will still be available for purchase at your local retailor, I can’t help but think about the relationship between these two categories of livestock products. Many animal health products available on the marketplace today are easily accessible and easy to use. However, because of this ease and without the detailed knowledge of a veterinarian, unfortunately, these products have been over and/or improperly used, thus leading to resistance. Resistance towards whatever we may be treating for is one of the main drivers for removal from retail shelves and being placed back into the hands of our veterinarians. Thinking a bit further as we begin our fast approach into peak grazing and parasite seasons, I can’t help but wonder what will happen to our currently supply of anthelmintics in the near future. Now hear me out, I’m not suggesting that these products also be removed from producers easy reach, but what I am pointing out is the need for judicious/calculated/careful or targeted used of these products.

With this being said, there are several management practices that can be implemented on-farm to reduce the losses associated with internal gastrointestinal parasitic infection through management or natural means. Of these management strategies, the use of plant bio-actives or secondary compounds have been shown to decrease the losses associated with parasitic infection by acting as a natural anthelmintic in addition to supplying the host with supplemental protein (Waller et al., 2001; Hoste et al., 2012). Among these secondary compounds, condensed tannins (CT) in the form of water soluble polyphenols, have shown to have a positive effect in combating parasitic infection (Hoste et al., 2006) and can be found in temperate forges such as birdsfoot trefoil, chicory, and sericea lespedeza (Domingo et al., 2019; Peña-Espinoza et al., 2017; Burke et al., 2012; Joshi et al., 2011).

According to Hoste et al. (2012), high tannin forages have two possible modes of action, direct and indirect. The direct mode of high tannin forages as a natural anthelmintic is supported by Brunet et al. (2008). In their experiment, the authors demonstrated that when comparing two groups of goats experimentally infected with a known amount of parasitic larvae, goats that were offered feeds that were tannin-rich (Lysiloma latisiliquum) demonstrated lower total larvae counts when slaughtered 5 days after larvae dosing when compared to controls. Furthermore, Hoste et al. (2006) demonstrated that when challenged in vivo with extracts from Lysiloma latisiliquum, larval and adult stages of Haemonchus contortus developed a covering over the anterior end, covering the buccal tooth, thus resulting in a reduced ability for the parasite to lyse and attach to the abomasal wall.

Indirectly, condensed tannins aid in providing supplemental protein to the host in the form of by-pass protein. In her doctoral dissertation, Martin (2016) outlines the complexity of tannin and protein binding, emphasizing that some proteins within high quality tannin forages may not be able to be used by the animal. In general, because of the high biding affinity between proteins and tannin polyphenols (Hoste et al., 2006), these bound protein complexes avoid ruminal degradation and by-pass to the abomasum. Once in the abomasum, Hoste et al. (2012) further explains that these protein complexes dissociate due to a low pH and amino acids from the previously bound proteins are passed to the small intestine where they can be absorbed. It is well known that parasitic infection results in blood loss leading to protein deficiency (Sykes and Coop, 2001). Supplemental protein, regardless of its form, has shown to aid in supporting the function of erythropoiesis (Shaw et al., 1995). In addition, Coop and Kyriazakis (2001) indicate that an influx in supplemental protein allows animals to better cope with parasitic infection due to the many functions that proteins support in developing and maintaining the function of the immune system.

This is just one of many strategies that a producer could implement to reduce the use of anthelmintics. Further investigating other natural means of parasite management, anecdotally, many have suggested the use of other natural products such as diatomaceous earth, oils, herds, and seeds or various plants, vegetables, and fruits. I’m not here to either support or discount the use of these strategies; however, I am hesitant on recommending any of these strategies at this time as there is an extremely limited amount of supporting evidence that suggests that these outlined natural remedies significantly reduce parasitic populations. Of the few papers I have been able to identify, da Silva et al. (2021) investigated the use of orange essential oil as natural method to reduce the severity of parasitic infection. Through their work, the authors noted a decrease in overall parasite numbers, but were unable to recommend this strategy as a sole treatment method and suggested that this strategy be used in conjunction with additional control methods. If there is additional supporting evidence that these natural products reduce parasitic nematode populations within the host, please share! I find this area of research to be quite intriguing and see the benefit of their potential uses within our production systems in the near future.

As always, Happy Shepherding!


  • Brunet, S., Martinez-Ortiz de Montellano, C., Torres-Acosta, J.F.J., Sandoval-Castro, C.A., Aguilar-Caballero, A.J., Capetillo-Leal, C., Hoste, H., 2008. Effect of the consumption of Lysiloma latisiliquum on the larval establishment of gastrointestinal nematodes in goats. Vet. Parasitol. 20, 81-88.
  • Burke, J.M., Miller, J.E., Mosjidis, J.A., Terrill, T.H., 2012. Use of a mixed sericea lespedeza and grass pasture system for control of gastrointestinal nematodes in lambs and kids. Vet. Parasitol. 189, 328-336.
  • Coop, R.L., Kyriazakis, I., 2001. Influence of host nutrition on the development and consequences of nematode parasitism in ruminants. Trends Parasitol. 17, 325-330.
  • da Silva, M.T.S.P., de Carvalho, M.B., Santana, D.A.D., dos Santos, S.K., Ollhoff, R.D., Luciano, F.B., Sotomaior, C.S., 2021. Can orange essential oil reduce the severity of parasitic infection in sheep? Vet. Parasitol. Regional Studies and Reports. 26, 1-6.
  • Domingo, J.M.P., Belesky, D.P., Crawford, C.D., Walsh, B., MacAdam, J.W., Bowdridge, S.A., 2019. Effects of grazing birdsfoot trefoil-enriched pasture on managing Haemonchus contortus infection in Suffolk crossbred lambs. J. Anim. Sci. 97, 172-183.
  • Hoste, H., Jackson, F., Athanasiadou, S., Thamsborg, S.M., Hoskin, S.O., 2006. The effects of tannin-rich plants on parasitic nematodes in ruminants. Trends Parasitol. 22, 253-261.
  • Hoste, H., Martinez-Ortiz de Montellano, C., Manolaraki, F., Brunet, S., Ojeda- Robertos, N., Fourquauz, I., Torres-Acosta, J.F.J., Sandoval-Castro, C.A., 2012. Direct and indirect effects of bioactive tannin-rich tropical and temperate legumes against nematode infection. Vet. Parasitol. 186, 18-27.
  • Joshi, B.R., Kommuru, D.S., Terrill, T.H., Mosjidis, J.A., Burke, J.M., Shakya, K.P., Miller, J.E., 2011. Effect of feeding sericea lespedeza leaf meal in goats experimentally infected with Haemonchus contortus. Vet. Parasitol. 178, 192-197.
  • Martin, D.G., 2016. The nutritional and anthelmintic effects of Calliandra calothyrsus condensed tannin in the gastrointestinal tract of merino sheep. (published Doctoral Dissertation). College of Public Health, Medicine, and Veterinary Sciences – James Cook University, Australia.
  • Peña-Espinoza, M., Williams, A.R., Thamsborg, S.M., Simonsen, H.T., Enemark, H.L., 2017. Anthelmintic effects of forage chicory (Cichorium intybus) against free-living and parasitic stages of Cooperia oncophora. Vet. Parasitol. 243, 204-207.
  • Shaw, K.L., Nolan, J.B., Lynch, J.J., Coverdale, O.R., Gill, H.S., 1995. Effects of weaning, supplementation and gender on acquired immunity to Haemonchus contortus in lambs. Int. J. Parasitol. 25, 381-387.
  • Sykes, A.R., Coop, R.L., 2001. Interaction between nutrition and gastrointestinal parasitism in sheep. New Zeal. Vet. J. 49, 222-226.
  • Waller, P.J., Bernes, G., Thamsborg, S.M., Sukura, A., Richter, S.H., Ingebrigtsen, K., Höglund, J., 2001. Plants as de-worming agents of livestock in the Nordic countries: Historical perspective, popular beliefs and prospects for the future.   Acta. Vet. Scand. 42, 31-44.