Effect of anthelmintic treatments on the performance of Nellore, Simmental and cross-breed Nellore X Simmental young cattle

Abstract

This study will be conducted in order to assess the factors related to the use of anthelmintics in Nellore, Simmental and cross-breed Nellore x Simmental young cattle naturally infected with gastrointestinal nematodes. Forty to 70 calves with 90 days of initial age and raised in four different farms will be evaluated. Calves will be kept in the same pasture, divided into three groups as follows: G1 treated every 28 days with a low efficacy anthelmintic (ivermectin), G2 - treated every 28 days with a high efficacy anthelmintic (albendazole sulphoxide or levamisole phosphate) and G3 - control group without treatment. Every 28 days the animals will be weighed and individual faecal samples will be collected for nematode faecal egg counts and production of third stage larvae in coprocultures. In the first sampling and then every four months blood will be collected for eosinophil counts, packed cell volume, total plasma protein and IgG anti-H. placei determination. (AU)