Efficiency of Moxidectin in Boophilus microplus tick control in cattle artificially infested / Eficiência do Moxidectin no controle do carrapato Boophilus microplus em bovinos artificialmente infestados

ABSTRACT

The efficacy of a Moxidectin subcutaneously injectable formulation in 0.1; 0.2, and 0.4mg Kg-1 body weight was evaluated compared with Ivermectin at 0.2 mg kg-1 and control group. Forty female Holstein yearling, randomly allocated in eight blocks, were artificially infested with 4,000 B. microplus larvae per day from 200mg of eggs in the –20; -17; -14; -7; -1; +5; +9 and +14 days (day 0= treatment day). The counts of semi-ingurged female ticks (4.5 to 8.0mm long) were carried out 21 days after each infestation. The average and the efficacy between the 4 to 20 count days were 982.8 for the control group, 160.3 (85.7%) for the Ivermectin treatment; 205.3 (81.8%), 94.1 (92.2%), and 58.7 (94.55%) for the Moxidectin treatment at 0.1; 0.2 and 0.4mg kg-1, respectively. Significant differences were found (P 0.05) between the control group and all treatments. No significant differences (P> 0.05) were found between Moxidectin 0.4mg kg-1 and Moxidectin and Ivermectin 0.2mg kg-1, respectively. The best treatments efficacy rates against larvae which infested 1 day before the treatments were 94.7% for Ivermectin 0.2mg kg-1 and 91.8%, 97.2%, and 99.7% for Moxidectin 0.1; 0.2 and 0.4mg kg-1, respectively. Infestations that occur 5 days after the treatments (counts on day +26) showed mean counts and efficacy of 165.5 for the control group; 174.5 (8.3%); 109.5 (45.9%), and 22.9 (87.8%) fo

RESUMO

Foi avaliada a eficácia de uma formulação injetável de Moxidectin, via subcutânea, nas dosagens de 0,1; 0,2 e 0,4mg kg-1 de peso corpóreo, comparada com a Ivermectina 0,2mg kg-1 e o grupo controle. 40 novilhas leiteiras, divididas em 8 blocos ao acaso, foram artificialmente infestadas com aproximadamente 4000 larvas de Boophilus microplus por dia, provenientes de 200mg de ovos, nos dias – 20; - 17; - 14; - 7; - 1; + 5; + 9; + 14 (dia 0= dia do tratamento) e as contagens de fêmeas semi-ingurgitadas ( 4,5 a 8mm de comprimento) realizadas 21 dias após cada infestação. As médias aritméticas dos totais de infestações e a eficácia entre os dias 4 a 20 de contagem foram de 982,8 para o grupo controle; 160,3 (85,7%) para a Ivermectina; 205,3 (81,8%); 94,1 (92,2%) e 58,7 (94,55%) para o moxidectin 0,1; 0,2 e 0,4mg kg-1, respectivamente. Houve efeito significativo (P 0,05) de todos os tratamentos em relação ao grupo controle. Entre os tratamentos, o Moxidectin 0,4mg kg-1 embora tenha mostrado melhor eficácia, não diferiu estatisticamente do Moxidectin 0,2mg kg-1 e da Ivermectina. As melhores eficácias dos tratamentos foram contra larvas que infestaram 1 dia antes dos tratamentos, sendo de 94,7% para Ivermectina 0,2mg kg-1 e de 91,8%; 97,2% e 99,7% para Moxidectin 0,1; 0,2 e 0,4mg kg-1, respectivamente. As infestações ocorridas 5 dias após o tratamento (contagem no dia +26), apresent