Orange oil emulsion has potential for control of Haemonchus contortus

Authors: Foster, Joyce; Turner, Kenneth; ZAJAC, ANNE - Virginia Polytechnic Institution & State University; Rosskopf, Erin

Submitted to: American Forage and Grassland Council Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/15/2009
Publication Date: 6/21/2009
Citation: Foster, J.G., Turner, K.E., Zajac, A.M., Rosskopf, E.N. 2009. Orange oil emulsion has potential for control of Haemonchus contortus. In: Proceedings of the American Forage and Grassland Council. 2009 Annual Conference, June 21-23, 2009, Grand Rapids, Michigan. 2009 CDROM.

Interpretive Summary: Haemonchus contortus is one of the most economically important gastrointestinal parasites in sheep and goats. Control is based on strategic use of pharmaceutical dewormers, but H. contortus has developed resistance to these anthelmintic drugs. In the absence of new drugs, discovery of plant materials with anthelmintic activity is critical to the sustainability of the small ruminant industry. This study was conducted to investigate the feasibility of using an emulsion containing oils from orange peels to control H. contortus. In vitro parasitology assays showed that treatment with emulsion containing 0.15% orange oils prevented hatching of H. contortus eggs and inhibited the motility of infective larvae. Application of emulsions containing 0.15 to 0.75% orange oils did not damage commonly used pasture plant species. Degradation of dried forages in the presence of orange oils in in vitro rumen fermentation assays paralleled that observed with soybean oil when the oils were present at a concentration (2%) typically used for dietary supplementation of ruminants. Results suggest that orange oil emulsions might be applied to pastures and administered to ruminants to effectively disrupt the life cycle of H. contortus. They provide the foundation for field and animal studies that are necessary before on-farm use of orange oil emulsions can be considered.

Technical Abstract: Haemonchus contortus, a gastrointestinal parasite that infects sheep (Ovis aries) and goats (Capra hircus hircus), is responsible for production losses and animal deaths worldwide. Pharmaceutical dewormers used to control H. contortus are becoming ineffective because this nematode species is rapidly developing resistance to all classes of the synthetic drugs. The objective of this study was to determine the feasibility of using an orange oil emulsion to control H. contortus. Treatment of isolated H. contortus eggs and infective third-stage larvae with an emulsion containing 0.1% orange terpene oil, 0.05% orange Valencia oil, 0.1% polysorbate 80 (emulsifier), and 0.0525% hydrogen peroxide prevented hatching of eggs and inhibited the motility of the larvae by 60%. Emulsion containing 0.15 to 0.75% orange oils did not cause visible damage to herbage when applied to commonly used pasture plant species (orchardgrass, Dactylis glomerata L.; red clover, Trifolium pratense L.; alfalfa, Medicago sativa L.; and chicory, Cichorium intybus L.). Degradation of dried forages in the presence of orange oils in in vitro rumen fermentation assays paralleled that observed with soybean oil when the oils were present at a concentration (2%) typically used for dietary supplementation of ruminants. Results suggest that orange oil emulsions might be applied to pastures and administered to ruminants to effectively disrupt the life cycle of H. contortus. They provide the foundation for field and animal studies that are necessary before on-farm use of orange oil emulsions can be considered.