Evaluation of encapsulated anethole and carvone in lambs artificially- and naturally-infected with Haemonchus contortus

Authors: KATIKI, L. - Instituto De Zootecnia; ARAUJO, R - Grasp Industria E Comercio Ltda; ZIEGELMEYER, L. - Instituto De Zootecnia; GOMES, A. - Instituto De Zootecnia; GUTMANIS, G. - Instituto De Zootecnia; RODRIGUES, L. - Instituto De Zootecnia; BUENO, M. - Instituto De Zootecnia; VERISSIMO, C. - Instituto De Zootecnia; LOUVNDINI, H. - The Center Of Nuclear Energy In Agriculture; Ferreira, Jorge; AMARANTE, A - Sao Paulo State University (UNESP)

Submitted to: Experimental Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2019
Publication Date: 1/8/2019
Citation: Katiki, L.M., Araujo, R.C., Ziegelmeyer, L., Gomes, A.C., Gutmanis, G., Rodrigues, L., Bueno, M.S., Verissimo, C.J., Louvndini, H., Ferreira, J.F., Amarante, A.F. 2019. Evaluation of encapsulated anethole and carvone in lambs artificially- and naturally-infected with Haemonchus contortus. Experimental Parasitology. 197:36-42. https://doi.org/10.1016/j.exppara.2019.01.002.
DOI: https://doi.org/10.1016/j.exppara.2019.01.002

Interpretive Summary: Natural, safe, and effective alternatives to control parasitic gastrointestinal helminths (worms) in sheep production systems are currently unavailable, and commercially-important worms, such as the barber pole worm (Haemonchus contortus), have developed tolerance to most available anthelmintics worldwide. This worm problem represents a huge economic threat to animal production systems and to the production of animal protein to feed a growing world population. Compounds from natural sources, such as essential oils, have shown activity against parasites in vitro, but have not been explored extensively in vivo. The essential oil components anethole and carvone (10% each) were encapsulated with 80% of an inert solid matrix (encapsulated essential oil components – EEOC) and tested in 2 experiments in vivo. In Experiment 1, lambs were artificially infected with a multi-drug resistant barber pole worm and treated with 50 mg/kg of EEOC in a controlled environment, while control animals were unifected and untreated. Thirty-two male lambs were kept in individual cages for a period of 45 days, after which they were evaluated for worm fecal egg count (FEC) and presence of adult worm, blood, toxicological, and nutritional status. When administered for 45 days at 50 mg/kg, EEOC was not toxic and provided a significant reduction in FEC. However, there was no difference in the clinical signs for the worm infection. Infected lambs, treated and untreated with EEOC, had similarly-low red blood cell count. Animals from both control and EEOC treatments had similar total adult worm count. The low FEC provided by the dose of 50 mg/kg EEOC reduced significantly both male worm size and female fecundity. Dry matter intake of uninfected healthy animals (controls) was significantly reduced by the 50 mg/kg EEOC dose. Thus, in Experiment 2, conducted for five months with lambs naturally infected with gastrointestinal parasitic worms, we used an EEOC dose of 20 mg/kg. Thirty four weaned lambs, free of parasites, were divided in two groups and kept in collective confinement. One group received EEOC at 20 mg/kg mixed with concentrate for 5 months, and the other was kept as a control group (CG). Both groups were evaluated for parasitological and blood parameters, and for body weight gain. In the first 2.5 months, CG group and EEOC groups were confined, and both presented similar clinical parameters. Then, animals were allowed to graze in contaminated pastures to acquire natural infection for the next 2.5 months. The infection was established after 25 days and both groups presented similar decrease in weight gain, increase in FEC, and decrease in blood parameters. Fecal cultures from CTL and EEOC groups established that parasite population was 90% barber pole worm. We concluded that the EEOC anethole and carvone, at either 20 or 50 mg/kg, although not toxic to animals, were not effective either to prevent or treat sheep naturally infected with parasitic worms or with a multidrug-resistant strain of the barber pole worm. This technology has proven safe and effective to deliver natural plant components, such as essential oils, to livestock at the farm level. However, an effective and safe natural worm killer for livestock is yet to be found.

Technical Abstract: Molecules from natural sources, such as essential oils, have shown activity against parasites in vitro, but have not yet been explored extensively in vivo. Anethole and carvone (10% each), encapsulated with 80% of a solid matrix, referred to as EO (encapsulated oils), were tested in vivo in 2 experiments. In Experiment 1: Lambs were artificially infected with multidrug resistant Haemonchus contortus, or left uninfected, and treated (or not) with 50 mg/kg bw (body weight) of EO in a controlled environment. Thirty-two male lambs were kept in individual cages for a period of 45 days, after which animals were evaluated for parasitological, hematological, toxicological, and nutritional parameters. After 45 days of treatment, EO at 50 mg/kg bw provided a significant (P=0.05) reduction in fecal egg count (FEC). Although FEC was reduced, animals from both treatments had similar counts of total adult worms. The low FEC was caused probably by a significant reduction (P=0.05) in both male worm size and female fecundity. Dry matter intake of uninfected controls was significantly (P=0.05) reduced, although no toxicity was observed in treated animals. Thus, in Experiment 2, conducted for five months we used an EO dose of 20 mg/kg bw. Thirty-four weaned lambs, free of parasites, were divided in two groups and kept in collective pens. One group received EO at 20 mg/kg bw mixed with concentrate for 5 months and the other was kept as a control group (CTL). Parasitological and hematological parameters as well as body weight were evaluated. In the first 2.5 months, CTL and EO groups were confined, and both presented similar clinical parameters. Then, animals were allotted to graze on contaminated pastures to acquire natural infection for the next 2.5 months. The infection was patent after 25 days and both groups had similar decreases in weight gain, increases in FEC, and decreases in blood parameters. Coprocultures from CTL and EO groups established that parasite population was 90% Haemonchus sp. We concluded that the technology of encapsulation is safe and practical to deliver to lambs at the farm level and anethole and carvone at 50 mg/kg bw caused a significant decrease in FEC and, consequently, in pasture contamination by free living stages of H. contortus. However, EO at 20 mg/kg bw was not effective to prevent or treat sheep naturally-infected with gastrointestinal nematodes.