PERSISTENT EFFECT OF INJECTABLE ABAMECTIN, DORAMECTIN, MOXIDECTIN ANDIVERMECTIN ON FECAL EGG COUNTS OF CALVES

The persistent effect of injectable formulations of abamectin, ivermec tin, moxidectin and doramectin was compared on the basis of a nematode egg output in 50 weaned grazing calves known to have been exposed to infective nematode larvae for four weeks prior to treatment. The cattl e weve allocated to the treatment groups by restricted randomisation o n the basis of faecal count on Day -6. Following the treatment on Day 0, the cattle were turned onto pasture as a single group. Faecal sampl es collected from each animal on Day 0 and weekly from Day 21 through Day 63 were examined for nematode eggs. Twenty-one days after treatmen t, the cattle treated with moxidectin had significantly (p<0.05) high faecal egg counts than cattle treated 1 with oxfendaxole, abamectin or doramectin. At 28, 35, 42 and 63 days after treatment, there were no significant differences among treatment groups. At Day 49, the cattle treated with ivermectin had significantly lower counts than the cattle treated with oxfendaxole, abamectin or moxidectin. At Day 56, the cat tle treated with ivermectin had significantly lower counts than the ca ttle treated with abamectin or moxidectin.