Sustainability of pasture ecosystems: The use of plant-based mixtures in the fight against helminths

Abstract

In developing countries, cattle grazing is associated with damage from contaminated manure as one of the hazardous types of organic waste. This, in turn, threatens the sustainability of various livestock sectors and causes significant economic losses. Such countries need to develop new sustainable strategies for integrated control of animal helminthiasis. Parasitic nematodes can significantly reduce the productivity and viability of agriculturally important mammals and are very common in human populations where sanitary standards are not met. In recent years, there has been a significant trend of parasite resistance to chemically synthesized veterinary treatment, including broad-spectrum anthelmintics. The chemicals used with anthelmintic properties pollute pasture ecosystems. In order to achieve environmentally sustainable development and mini m ize the impact of these substances on the environment we determined in a laboratory experiment investigating the effects of eugenol, isoeugenol, thymol and carvacrol, individually and in paired mixtures, on Strongyloides papillosus and Haemo n chus contortus larvae and Trichiuris vulpis and Toxocara canis eggs. Mortality of S. papillosus larvae exposed to a 0.01% mixture of isoeugenol and thymol (97.5 ± 1.7%), eugenol and thymol (96.6 ± 2.6%), and thymol and carvacrol (92.0 ± 5.8%) exceeded 90%. Under the influence of a mixture of 0.01% eugenol and isoeugenol (89.1 ± 10.3%), eugenol and carvacrol (88.2 ± 8.5%), mortality was insignificantly reduced. Haemonchus contortus larvae were significantly more resistant to the influence of mixtures of 0.01% of the studied substances: maximum mortality was noted for eugenol and isoeugenol (80.0 ± 10.6%), eugenol and thymol (86.8 ± 9.6%). Under the influence of 0.1% of the studied substances applied separately, morta l ity of T. vulpis eggs reached its maximum for carvacrol (80.2 ± 11.4%), was significantly lower for thymol (55.3 ± 7.5%) and remained at the level of the control group (without influence of either of the substances) for eugenol and isoeugenol. Average mortality of T. vulpis eggs exceeded 90% when exposed to 1.0% thymol, eugenol, and isoeugenol. At this dosage, carvacrol inflicted the lowest mortality of the four substances studied for T. vulpis eggs. Under the influence of mixtures of these substances for 24 hours, larvae subsequently formed in the eggs of Trichiuris vulpis and Toxocara canis in more than 68% of cases. Mortality of eggs of T. vulpis was highest when exposed to a mixture of isoeugenol and carvacrol. Among the studied nematode species, the eggs of T. canis turned out to be the most resistant to the mixtures of the studied substances: the mortality of eggs did not exceed 16%. Our research results show that mixtures of even very low concentrations of eug e nol with thymol can reduce the viability of larvae of nematode species that are important in medicine and veterinary med i cine