Comparative anthelmintic efficacy between different active principles in young sheep

Abstract

The objective of the present study was to verify the efficacy of different anthelmintics in young sheep and the variation between males and females. The work was carried out between March and April 2015 in private property in the municipality of Dom Pedrito - RS. The evaluations were carried out on 180 lambs (90 males and 90 females) crossed Corriedale x Ile de France with mean age of 10 ± 2 months live weight (LW) of 26.00 ± 2.0 kg kept in intermittent grazing with fixed stocking In 20 hectares (ha) of native field. The animals were separated into three groups which received different active principles (Closantel 10% via oral; 30% oral Diophenol and 34% Nitroxinil via injectable). Each group consisted of 60 individuals 30 males and 30 females. The faeces were collected before the application of the active principle (day zero) and after 10 days for the quantification of eggs per gram of faeces (OPG). Also the cultivation of larvae (coproculture) was carried out. The efficacy test was checked according to the following formula Efficacy (E%) = [(OPG control day0 – OPG treatment day10) /OPG day0 ] x 100. All OPG averages were found to be above the maximum dosage limit (OPG> 500). The anthelmintic efficacy in the herd for Closantel dysophenol and Nitroxinil was 64% -7% 60% respectively and efficacy less than 90% is sufficient to presume the resistance of helminths to these drugs. When efficacy was observed between the sexes it was found that all drugs were considered ineffective. However it is worth noting that the efficacy of the active ingredient Nitroxinil was 72% in lambs and 33% in lambs. The population of nematodes identified in the coproculture of the herd referring to day 0 was Haemonchus spp. (45%) followed by Trichostrongylus spp. (53%) and with fewer occurrences Bonostomum spp. (2%). When identification was performed after treatments (day 10) the presence of Haemonchus spp. (43%) Trichostrongylus spp. (56%) and Bonostomum spp. (1%). Efficacy and coproculture tests should be carried out periodically in the herd in order to guide the selection of the most appropriate anthelmintic in the control of verminosis. Comprovou-se que na propriedade há resistência anti-helmíntica aos princípios ativos utilizados. Embora, fosse verificada maior eficácia nas cordeiras fêmeas tratadas com Nitroxinil em comparação aos machos do mesmo grupo, ambos foram considerados ineficazes no combate à parasitose.