| Autor: |
Pivoto FL; Departamento de Clínica de Grandes Animais (DCGA), Universidade Federal de Santa Maria (UFSM), Av. Roraima 1000, Santa Maria, RS, 97105-900, Brazil. felipe.pivoto@gmail.com., Cezar AS; Universidade Regional do Noroeste do Estado do Rio Grande do Sul (UNIJUI), Ijui, RS, Brazil., Vogel FSF; Departamento de Medicina Veterinária Preventiva (DMVP), Centro de Ciências Rurais (CCR), UFSM, Santa Maria, RS, Brazil., Marques CB; Departamento de Medicina Veterinária Preventiva (DMVP), Centro de Ciências Rurais (CCR), UFSM, Santa Maria, RS, Brazil., Alves MEM; Departamento de Medicina Veterinária Preventiva (DMVP), Centro de Ciências Rurais (CCR), UFSM, Santa Maria, RS, Brazil., Becker CC; Departamento de Agrometeorologia, UFSM, Santa Maria, RS, Brazil., do Rego Leal ML; Departamento de Clínica de Grandes Animais (DCGA), Universidade Federal de Santa Maria (UFSM), Av. Roraima 1000, Santa Maria, RS, 97105-900, Brazil. |
| Abstrakt: |
The aim of this study was to compare the economic revenue related to the use of low- or high-efficacy anthelmintic drugs within suppressive or strategic schemes of treatment in growing heifers. Heifers raised in a semi-intensive grazing system in southern Brazil were used. Levamisole and ivermectin were selected as the high- and the low-efficacy drugs, respectively, based on a previous efficacy test. Subsequently, these drugs were used within strategic (Strat; four times per year) or suppressive (Supp; once a month) treatment regimens in the heifers, and their liveweight and eggs per gram of feces counts were monthly evaluated during a 13-month period. The total costs of the treatments and their cost-benefit ratio in regard to liveweight gain were calculated. Final mean liveweight gains (kg) observed were 126.7 (Strat-Low), 133.6 (Supp-Low), 141.3 (Strat-High), 142.9 (Supp-High), and 125.8 (Control). Treatments with a high-efficacy drug resulted in monetary gains of US$ 19.56 (Strat-High) and US$ 14.98 (Supp-High), but Supp-Low and Strat-Low treatments caused economic losses. Total cost of the efficacy test (US$ 374.79) could be paid by the additional liveweight gain of 20 heifers from the Strat-High group. These results showed that it would be preferable not to treat the heifers against GIN if compared with treating them with a low-efficacy drug. In addition, we showed that the use of four treatments per year with a high-efficacy drug-selected by efficacy test-resulted in a profitable management to control GIN in growing heifers raised in a semi-intensive gazing system in southern Brazil. |
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