<abstract xmlns="http://www.w3.org/1999/xhtml">

<p>The increasing prevalence of anthelmintic resistance in cattle especially for avermectins, is a challenge for controlling parasites in some herds. Thus, field studies demonstrating the increase in productivity by the use of anthelmintic formulations, even when a suboptimal treatment (efficacy below 95%), can contribute to the development of gastrointestinal nematodes control programs in beef cattle. The objective of the present study was to evaluate the anthelmintic efficacy and productive performance in pasture-raised beef calves, treated with macrocyclic lactones. A Split plot in time randomized block design was used to assess weight gain and reduction in fecal egg count (FECs) of treatments: 1% moxidectin (1% MOX), ivermectin (IVM) and abamectin (ABM) (2.25% IVM+1.25% ABM), 4% IVM, 3.15% IVM and placebo. For the evaluation of FECs and weight gain of the animals, individual samples were collected seven days before treatment and, +14, +30, +56, +91 and +118 days post-treatment (DPT). The efficacies in the 14th DPT were: 72.3% (1% MOX), 22.1% (4% IVM), 22% (2.25% IVM + 1.25% ABM) and 0% (3.15% ivermectin). 1% MOX was the only treatment that resulted in a significant increase in weight gain of the animals compared to the placebo group after 118 days of treatment, with a difference of 7.6 kg. Therefore, MOX remains a viable alternative for the control of helminths resistant to avermectins and still capable of resulting in significant productive gains, even with an efficacy below 95%.</p>
</abstract>

The increasing prevalence of anthelmintic resistance in cattle especially for avermectins, is a challenge for controlling parasites in some herds. Thus, field studies demonstrating the increase in productivity by the use of anthelmintic formulations, even when a suboptimal treatment (efficacy below 95%), can contribute to the development of gastrointestinal nematodes control programs in beef cattle. The objective of the present study was to evaluate the anthelmintic efficacy and productive performance in pasture-raised beef calves, treated with macrocyclic lactones. A Split plot in time randomized block design was used to assess weight gain and reduction in fecal egg count (FECs) of treatments: 1% moxidectin (1% MOX), ivermectin (IVM) and abamectin (ABM) (2.25% IVM+1.25% ABM), 4% IVM, 3.15% IVM and placebo. For the evaluation of FECs and weight gain of the animals, individual samples were collected seven days before treatment and, +14, +30, +56, +91 and +118 days post-treatment (DPT). The efficacies in the 14th DPT were: 72.3% (1% MOX), 22.1% (4% IVM), 22% (2.25% IVM + 1.25% ABM) and 0% (3.15% ivermectin). 1% MOX was the only treatment that resulted in a significant increase in weight gain of the animals compared to the placebo group after 118 days of treatment, with a difference of 7.6 kg. Therefore, MOX remains a viable alternative for the control of helminths resistant to avermectins and still capable of resulting in significant productive gains, even with an efficacy below 95%.

Moxidectin: A Viable Alternative for the Control of Ivermectin-Resistant Gastrointestinal Nematodes in Beef Cattle

Laboratory of Parasitic Diseases, Faculty of Veterinary Medicine and Animal Science

Faculty of Veterinary Medicine and Animal Science

Acta Veterinaria

This work is licensed under the Creative Commons Attribution 4.0 International License.

The increasing prevalence of anthelmintic resistance in cattle especially for avermectins, is a challenge for controlling parasites in some herds. Thus, field...

Moxidectin: A Viable Alternative for the Control of Ivermectin-Resistant Gastrointestinal Nematodes in Beef Cattle

Publicado en línea: 05 abr 2022

Páginas: 16 - 29

Recibido: 11 ago 2021

Aceptado: 08 mar 2022

DOI: https://doi.org/10.2478/acve-2022-0002

Palabras clave
Anthelmintic, macrocyclic lactones, resistance, ruminants

© 2022 Dyego Gonçalves Lino Borges et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Moxidectin: A Viable Alternative for the Control of Ivermectin-Resistant Gastrointestinal Nematodes in Beef Cattle

Publicado en línea: 05 abr 2022

Páginas: 16 - 29

Recibido: 11 ago 2021

Aceptado: 08 mar 2022

DOI: https://doi.org/10.2478/acve-2022-0002

Palabras claveAnthelmintic, macrocyclic lactones, resistance, ruminants

© 2022 Dyego Gonçalves Lino Borges et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Palabras clave
Anthelmintic, macrocyclic lactones, resistance, ruminants