Researchers in Ontario, Canada, reported on a study in which they compared whole flock treatments (WT) vs. targeted selective treatment (TST) of periparturient ewes. Six client-owned farms were utilized in the study.
On the whole treatment farms (n=3), all of the ewes were treated with an anthelmintic at lambing (closantel @10 mg/kg). On the TST farms (n=3), ewes were only treated if they met at least one of four criteria: 1) the last grazing season was the first grazing season; 2) body condition score <2; 3) FAMACHA© score >4; or 4) nursing 3 or more lambs.
The number of animals treated on TST farms was reduced by as much as 47 percent. Parasite burdens were higher on TST farms, but fecal egg counts were not significantly different. The number of additional anthelmintic treatments or deaths attributed to parasitism did not differ between treatment groups.
The study demonstrated that TST can be effective if accurate indicators are used to identify animals to treat.
Source: Small Ruminant Research Journal, May 2017.