A review of regional and temporal use of avermectins in cattle and horses worldwide.

The research article focuses on the analysis of the use of avermectins – a group of parasiticides, specifically ivermectin and abamectin, for treating parasitic diseases in cattle and horses worldwide, and gauges the potential impact of avermectin residues in feces on pasture ecology.

Background of Avermectins

• Avermectins, including ivermectin and abamectin, are a group of broad-spectrum antiparasitic agents.
• Ivermectin was first registered in 1981 as an injectable treatment for cattle, while abamectin was later registered for the same purpose.
• Particularly, the use of avermectins among farmers and veterinarians is evident due to their broad activity, convenience, safety margin, and the corresponding improved health and performance of the livestock.

Use of Avermectins

• For cattle and other grazing animals, the application of avermectins aligns with that of other antiparasitics, especially anthelmintics, where the usage patterns are formed based on integrated practical management considerations and disease epidemiology knowledge.
• Generally, programmes are aimed at controlling abomasal nematodes, with the preferred times for treatment being the end of the nematodes’ transmission period, often aligning with the livestock’s rehousing, feedlot entry, or move to a new pasture.
• The added benefit of simultaneous ectoparasite control at this time is also emphasized.
• Young, first-season grazing cattle are the primary targets for prophylactic use of avermectins at pasture.
• On the other hand, a bimonthly treatment regimen during hazardous periods has proven beneficial in preventing potential damage from major parasitic threats, such as large and small strongyles and stomach bots, in horses.

Impact on Pasture Ecology

• The study explored the potential for avermectin residues in feces to affect pasture ecology.
• The findings suggest that any effects, if present, would be spatially and temporally limited.
• Moreover, no significant impact on pasture ecology and the environment after over a decade of practical avermectins usage is observed, signifying their relative safety for the environment.