Efficacy of an in-feed ivermectin formulation against gastrointestinal helminths, lungworms, and sarcoptic mites in swine.

The efficacy of ivermectin as an in-feed formulation was evaluated against naturally acquired gastrointestinal helminths, lungworms, and sarcoptic mites (experiment 1; n = 24) and against induced infection with intestinal nematodes (experiment 2; n = 24) in pigs. Treatments consisted of ivermectin administered in feed at concentrations calculated to provide 100 or 200 micrograms/kg of body weight/d for 7 days or of nonmedicated feed (controls) for 7 days. At concentration of 100 micrograms of ivermectin/kg/d, efficacy against naturally acquired infections was 97.7% for Ascaris suum, 97.8% for Metastrongylus spp, greater than 99% for Oesophagostomum spp, 100% for Macracanthorhynchus hirudinaceus, and 89.7% for Ascarops strongylina. Against induced infections (fourth-stage larvae), efficacy was 100% for A suum and 96.9% for Oesophagostomum spp. At concentration of 200 micrograms of ivermectin/kg/d, efficacy against naturally acquired infections was 100% for A suum, Hyostrongylus rubidus, Metastrongylus spp, and Ascarops strongylina; greater than 99% for Oesophagostomum spp; and 85.9% for Macracanthorhynchus hirudinaceus. Against induced infections (fourth-stage larvae), efficacy was 100% for A suum and 95% for Oesophagostomum spp. At concentrations of 100 and 200 micrograms of ivermectin/kg/d, efficacy against Sarcoptes scabiei var suis was evidenced by elimination of the mite by posttreatment day 14.

Effect of efrotomycin on gain and feed efficiency for pigs from weaning until market weight.

Six studies involving 700 pigs were conducted in five separate swine research facilities to evaluate weight gain and efficiency of feed utilization in pigs fed the antibiotic efrotomycin. Pigs averaging 8.4 kg at the beginning of the studies were fed fortified corn-soybean meal diets that contained efrotomycin at 0, 2, 4, 8 or 16 ppm for an average of 120 d to market weight, about 92.1 kg. Pigs fed efrotomycin gained 5.9 to 8.9% faster (P less than .01) and were 1.7 to 4.0% more efficient (P less than .01) than those fed control diets. The improvement in growth rate was linear from 2 through 16 ppm, while feed efficiency (gain/feed) plateaued at 4 ppm efrotomycin. Treatment X study interactions were not significant for average daily gain or feed efficiency, showing that the response to efrotomycin was similar in each study. These studies indicate that efrotomycin is effective in improving gain and efficiency of feed utilization in swine from weaning until market weight.

Efficacy of ivermectin against the mange mite Sarcoptes scabiei var suis in pigs.

The efficacy of ivermectin administered by esophageal intubation in a single dose was evaluated against the mange mite Sarcoptes scabiei var suis in 24 naturally infested pigs. Six pigs were allocated to each of the 4 treatment groups. Control (group 1) pigs were given nonmedicated water, group 2 were given ivermectin at 300 micrograms/kg of body weight, group 3 were given ivermectin at 400 micrograms/kg, and group 4 were given ivermectin at 500 micrograms/kg. The pigs were examined for S scabiei before treatment and on days 7, 14, 21, and 28 after treatment. Of the 18 ivermectin-treated pigs, 10 had no live S scabiei recovered on day 7 after treatment, 16 had none on day 14, 18 had none on day 21, and 16 had none on day 28. All 6 nonmedicated control pigs had live S scabiei recovered on days 7 and 21, and 5 control pigs had mites on days 14 and 28. The single administration of ivermectin given by esophageal intubation was highly effective in reducing the number of S scabiei at all dose levels tested. The pooled ivermectin-treated groups had significantly (P less than 0.01) fewer mites than the control group on all posttreatment examination days. There were no statistically significant differences among the ivermectin dose levels.