Investigating the benefits of targeted selective treatment according to average daily weight gain against gastrointestinal nematodes in Morada Nova lambs

Author(s):Show less -

dos Santos, Isabella Barbosa ; Anholeto, Luis Adriano ; de Sousa, Gustavo Avelar ; Nucci, Alessandra da Silva ; Gainza, Yousmel Aleman ; Figueiredo, Amanda ; Lima dos Santos, Leonardo Aparecido ; Minho, Alessandro Pelegrine ; Barioni-Junior, Waldomiro ; Esteves, Sergio Novita ; Meo Niciura, Simone Cristina ; de Souza Chagas, Ana Carolina

• Document type: Journal article
• Source: Parasitology Research; v. N/A, p. 12-pg., 2022-05-28.

Abstract

The objective of this study was to evaluate a method of targeted selective treatment (TST) of Morada Nova lambs, based on the average daily weight gain (DWG). For this, 114 lambs in the rainy and 102 in the dry season were randomized into three treatments: control (CT), routine (RT, treated every 42 days), and targeted selective (TST, treated according to DWG). Packed cell volume (PCV) and eggs per gram of feces (EPG) tests were performed. The anthelmintic resistance of parasites was assessed by the EPG count reduction test (FECRT), RESISTA-Test(C), and molecular test. For CT, RT, and TST groups, the following results were obtained: mean EPG values were 4665.1, 3063.5, and 3462.1 in the rainy season and 4475.1, 1341.7, and 2863.4 in the dry season, respectively; mean PCV values were 32.1, 33.4, and 32.3% in the rainy season and 33.9, 36.0, and 35.1% in the dry season; mean DWG readings were 0.087, 0.101, and 0.094 kg in the rainy season and 0.102, 0.113, and 0.112 kg in the dry season; efficacies of levamisole in FECRT were 66.4, 24.1, and 76.4% in the rainy and 90.7, 12.4, and 64.8% in the dry season, respectively; in the RESISTA-Test(C), the LC50 values were 0.482, 1.926, and 0.117 mu g.mL(-1) in the rainy and 0.437, 0.851, and 0.045 mu g.mL(-1) in the dry season, respectively; the frequencies of the homozygous-resistant genotype were 57.1, 71.4, and 40.0% in the rainy and 47.8, 55.9, and 41.9% in the dry season. In conclusion, TST reduced the development of resistance through refugia maintenance, without productive losses, contributing to the sustainability of sheep breeding. (AU)

• FAPESP's process: 19/02929-3 - Target selective treatment based on liveweight gain as nematode control strategy in Morada Nova lamb
• Grantee: Ana Carolina de Souza Chagas
• Support Opportunities: Regular Research Grants
• FAPESP's process: 18/16070-1 - Study of the impact of gastrointestinal nematodes infection on the performance of Morada Nova Lambs for development of a targeted selective treatment
• Grantee: Isabella Barbosa dos Santos
• Support Opportunities: Scholarships in Brazil - Doctorate