Resumen

SANDOVAL, Espartaco et al. Evaluation of a selective control program in dual purpose calves infected with digestive strongylid. Zootecnia Trop. [online]. 2009, vol.27, n.2, pp.215-219. ISSN 0798-7269.

In order to evaluate the impact of a program of gastrointestinal strongylid selective control, 35 crossbreed calves reared under continuous grazing in a dual purpose farm were used. The farm is located in an area classified as tropical dry forest in Yaracuy state (Venezuela). Calves were coproscopically examined every 15 days by means of the McMaster technique and the results expressed in egg per gram of feces. All the calves with high infestation degree were drenched during the next sampling with a long persistence anthelmintic product (Ivermectine 3.5%). Haematocric and live weight were also determined. Calves that were not required to be drenched were subjected to the same evaluation monthly. The results showed a continuous diminution of the proportion of calves with high infestations degree, which started in 28.6%, but at the end of the observation period this percentage was only 14.3%. The high infestation degree in animals that were able to maintain acceptable productive levels indicate that these calves were resilients. The importance of selective anthelmintic treatment of the resilient fraction within the herd for gastrointestinal strongylids control is discussed.

Palabras clave : strongylids; selective control; resilience; bovine.

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