title: A fenbendazole oral drench in addition to an ivermectin pour-on reduces parasite burden and improves feedlot and carcass performance of finishing heifers compared with endectocides alone.
abstract: Two studies utilizing 1,862 yearling heifers were conducted to determine the effects of a fenbendazole oral drench in addition to an ivermectin pour-on (SG+IVPO), compared with an ivermectin pour-on (IVPO) or a doramectin injectable (DMX) alone, on parasite burden, feedlot performance, and carcass merit of feedlot cattle. In the first study, heifers receiving the SG+IVPO had fewer (P = 0.02) cattle retreated for disease and 73% fewer (P = 0.06) worm eggs per fecal sample 98 d after treatment than heifers treated with IVPO. Heifers treated with SG+IVPO consumed more DM, had greater ADG, were heavier at slaughter, and had heavier carcasses than IVPO-treated heifers (P < 0.05). Heifers treated with SG+IVPO also had more (P = 0.07) carcasses grading USDA Prime or Choice than IVPO-treated heifers. In the second study, heifers treated with SG+IVPO had fewer (P < 0.01) worm eggs per fecal sample 35 d after treatment and had fewer numbers of adult and larval Cooperia and Trichostrongylus spp. in the small intestine at slaughter (P < 0.10) compared with heifers treated with DMX. Heifers treated with SG+IVPO consumed more DM, were heavier at slaughter, and had heavier carcasses than DMX-treated heifers (P < 0.01). The SG+IVPO-treated heifers also had greater ADG (P < 0.10). The broad-spectrum effectiveness of a combination of a fenbendazole oral drench and an ivermectin pour-on reduced parasite burden and increased feed intake, ADG, and carcass weight in feedlot heifers compared with treatment with an endectocide alone.
authors.affiliation: Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506, USA. cdr3@ksu.edu
authors.forename: C D
authors.initials: CD
authors.lastname: Reinhardt
authors.forename: J P
authors.initials: JP
authors.lastname: Hutcheson
authors.forename: W T
authors.initials: WT
authors.lastname: Nichols
mesh_terms: D000284:Administration, Oral; D000287:Administration, Topical; D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage / Q000494:pharmacology; D001823:Body Composition / Q000187:drug effects*; D002417:Cattle / Q000502:physiology*; D005260:Female; D005273:Fenbendazole / Q000008:administration & dosage* / Q000494:pharmacology; D006374:Helminthiasis, Animal / Q000517:prevention & control; D007559:Ivermectin / Q000008:administration & dosage* / Q000031:analogs & derivatives / Q000494:pharmacology; D015430:Weight Gain / Q000187:drug effects*
chemical_list: D000871:Anthelmintics; D005273:Fenbendazole; D007559:Ivermectin; C084101:doramectin