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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. Graphical abstract Image 1 Highlights • 50 mg/kg (25 mg/kg of anethole + 25 mg/kg of carvone) encapsulated oils (EO) during 45 days reduced lambs FEC. • 50 mg/kg EO reduced adult male length and eggs per adult female H. contortus. • - 50 mg/kg EO had no effect on liver and kidney function of lambs. • 50 mg/kg EO reduced body weight gain and feed intake of lambs non- infected with H. contortus. • 20 mg/kg (10 mg/kg of anethole + 10 mg/kg of carvone) EO given to lambs during 5 months were not effective reduce FEC. [ABSTRACT FROM AUTHOR]

The inclusion of industrial byproducts such as citrus pulp in the composition of animal diets has been widely recommended due to sustainability aspects and their high level of carbohydrates. Limonene is found in citrus pulp and has been described elsewhere as a major compound of citrus essential oils with excellent anthelmintic activity. The objective of this study was to evaluate the parasitological parameters of lambs artificially infected (Experiment 1) with Haemonchus contortus and naturally infected (Experiment 2) by gastrointestinal nematodes, fed diets with dehydrated citrus pulp or silage of moist orange pulp. Both experiments had three treatments (C: control, DP: diet + dehydrated citrus pulp, and MP: diet + silage of moist orange pulp). The diets were isoproteic (11% crude protein) and the concentrate was corrected every 14 days according to animal weight. Parasitological parameters were evaluated for both experiments each 14 days (body weight, body condition; fecal egg counts-FEC, egg hatch assay-EHA, coproculture, and packed cell volume-PCV). Analysis of variance (GLM of the SAS software) was performed with repeated measures in time, and the means were compared by the Tukey test. Gas chromatography with mass spectrometry was used to detect constituents of dry or moist citrus pulp. Dehydrated citrus pulp had 0.02% essential oil (major compounds were 85.9% limonene and 7.6% valencene). Moist orange pulp contained 1.5% essential oil (major compounds were 65.5% limonene and 31.2% alpha- and gamma-terpineol). In both experiments, the weight gain among the treatments was similar ( p > 0.05) demonstrating that both moist and dehydrated orange pulp can be used to replace corn kernels to feed infected lambs. The supplementation with orange pulp did not decrease natural or artificial infections of gastrointestinal nematodes according to the FEC results ( p > 0.05). However, PCV increased from animals fed dehydrated and moist pulp in natural infection (Experiment 2, p < 0.05) in comparison with the control group. In addition, the consumption of the dehydrated citrus pulp from animals infected with H. contortus (Experiment 1) caused lower hatching rates after 42 days of consumption ( p < 0.05), suggesting a tendency to shed fewer eggs to the environment. [ABSTRACT FROM AUTHOR]