Comparison of two methods for the quantification of gastrointestinal nematode infective larvae from pasture

Author(s)

Sabiao de Toledo Piza, Marina Lais ^[1] ; de Almeida, Fabiana Alves ^[2] ; Pariz, Cristiano Magalhaes ^[3] ; Costa, Ciniro ^[3] ; Talamini do Amarante, Alessandro Francisco ^[2]

Affiliation

^[1] Univ Estadual Paulista, Fac Med Vet & Zootecnia, UNESP, Programa Posgrad Zootecnia, Botucatu, SP - Brazil

^[2] UNESP, Dept Parasitol, Inst Biociencias, Botucatu, SP - Brazil

^[3] UNESP, Dept Melhoramento & Nutr Anim, Botucatu, SP - Brazil

• Document type: Journal article
• Source: SEMINA-CIENCIAS AGRARIAS; v. 40, n. 2, p. 713-722, MAR-APR 2019.
• Web of Science Citations: 1

Abstract

The economic losses caused by gastrointestinal nematodes are one of the biggest obstacles in the small ruminants production. Understanding the population dynamics of the infective larvae (L3) in the pasture is the key point to develop control programs, and reliable results depend on the used methodology to quantify L3 numbers. The use of the sampling directly from the pasture appears as a viable option, since it is not required the use of animals with an esophageal fistula or tracer animals, decreasing the costs involved in the study. Therefore, the present project. which had as objective evaluate the efficiency of two collection methods for quantification of L3 in the pasture, utilized 64 lambs (n = 16) allocated to four integrated crop-livestock systems (treatments) with 12 paddocks each. Pasture samples were collected every nine days. The W method consists in traversing the area in the form of a W and again an inverted W, forage samples being collected every 10 steps, and the Square method, in tossing a 0.16 m(2) square to four random points within the area, the forage within the square being collected after each toss. After the forage samples had been processed, the L3 were recovered and identified. Cohen's Kappa coefficient (k) was determined. The W-transect and Random-plot methods did not differ (p >= 0.05) with respect to the number of L3 recovered from the pasture. and a positive correlation was found between them, suggesting agreement with one another, being that when the number of L3 recovered by the W-transect method increases, the same occurs in the Random-plot technique. The Random-plot method, which is already used to collect samples of forage for chemical analyses, can also be employed to estimate the pasture contamination by L3. The W-transect and Random-plot methods showed to be important in the epidemiological study of gastrointestinal nematodes in sheep. Therefore, the use of both on the same occasions and with different purposes, with one complementing the information that is not provided by the other, may be more effective in the investigation of enviromental contamination by L3 of gastrointestinal nematodes. (AU)

• FAPESP's process: 13/13702-3 - Production of corn silage in intercrop with palisadegrass and pigeon pea and oat oversseeded modality to lambs finishing in semi-feedlot
• Grantee: Cristiano Magalhães Pariz
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 15/25413-1 - Integrated crop-livestock system as grassland contamination control method for gastrointestinal helminths of sheep
• Grantee: Marina Lais Sabião de Toledo Piza
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 15/25718-7 - Prophylaxis of sheep worms using integrated crop-livestock system (ICL)
• Grantee: Fabiana Alves de Almeida
• Support Opportunities: Scholarships in Brazil - Post-Doctoral