title: Effects of an integrated control programme with ivermectin on growth, carcase composition and nematode infection of beef cattle in Argentina's western pampas.
abstract: The effect of previous pasture management and ivermectin treatment on gastrointestinal parasitism, weight gain and carcase composition of steers was studied in the semiarid Pampeana region of Argentina from April 1986 to April 1987. Three groups, each of 15 weaned calves, were grazed on separate lucerne pastures. Group 1 control calves, which grazed paddocks previously grazed by nematode-infected weaners and yearlings with a high nematode egg output, were only medicated when heavy parasitism was recorded. Group 2 calves, which grazed paddocks previously infected by steers at least two and a half years old with low nematode egg output, were treated strategically with ivermectin. Group 3 calves, which grazed on 'clean' paddocks, were treated monthly with ivermectin. Group 1 calves showed heavy parasitism and parasitological parameters were higher than in groups 2 and 3. The liveweight gain responses of groups 2 and 3 were significantly greater than those of group 1 (P less than 0.001) during autumn, winter and early spring. At the end of the study when cattle reached market condition, the liveweight gains of groups 2 and 3 were 74.1 and 81.9 kg, respectively, greater than group 1. Carcase analyses showed significantly greater weight and killing-out percentages in groups 2 and 3 than in group 1. Reduced total bone, muscle and fat weights were observed in group 1.
authors.affiliation: INTA, Estación Experimental Agropecuaria de Anguil, La Pampa, Argentina.
authors.forename: V H
authors.initials: VH
authors.lastname: Suarez
authors.forename: D O
authors.initials: DO
authors.lastname: Bedotti
authors.forename: S
authors.initials: S
authors.lastname: Larrea
authors.forename: M R
authors.initials: MR
authors.lastname: Busetti
authors.forename: C A
authors.initials: CA
authors.lastname: Garriz
mesh_terms: D000818:Animals; D001118:Argentina; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy* / Q000517:prevention & control; D005243:Feces / Q000469:parasitology; D007559:Ivermectin / Q000627:therapeutic use*; D008297:Male; D009349:Nematode Infections / Q000188:drug therapy / Q000517:prevention & control / Q000662:veterinary*; D010270:Parasite Egg Count / Q000662:veterinary; D012621:Seasons; D015430:Weight Gain / Q000187:drug effects
chemical_list: D007559:Ivermectin