The efficacy and acceptability of
eprinomectin in a topical formulation against gastro-intestinal nematodes in cattle was assessed under field conditions. Seven similar commercial dairy farms in the North and South Islands of New Zealand were included in the studies, involving 247 Holstein-Friesian, Jersey or Jersey-cross cattle. Cattle were confirmed by positive faecal nematode egg counts to have natural
infections of gastro-intestinal nematodes and were held in separate treatment groups. In each replicate, four animals received
eprinomectin (500 microg/kg
body weight) and one animal received vehicle
solution, all applied topically at 1 ml/10 kg
body weight. Faecal samples were collected before, and 14 days
after treatment, for faecal trongylid egg counts. Animals treated with
eprinomectin had significantly lower (p < 0.05) Day 14 faecal strongylid egg counts than the controls. There were no significant differences (p > 0.10) between treated and control groups for pretreatment strongylid egg counts. No formulation runoff or adverse reactions were observed. These studies showed
eprinomectin to be effective against gastro-intestinal
nematode infections and safe for use in dairy cattle under natural field conditions.