DISTRIBUTION AND ABUNDANCE OF DIGESTIVE STRONGYLES EGGS IN NATURALLY INFECTED BOVINES

Objective. To quantify the prevalence and parasitic burdens of strongyles in naturally infected bovine herds in an important western cattle production area in Falcon state, Venezuela. Materials y methods. Four ranches with the “Carora” breed (result of crossing Holstein, Swiss Brown, Zebu) were sampled over a seven month period. Every month cattle were examined by the McMaster coprological technique. In each ranch, sampling was stratified among four age groups (calves: 0-6 mo; “maute”: 7-12 mo; heifers: 13-24 mo; adults: >25 mo). Results. A total of 1140 samples were collected. Mean prevalence values were 31.06- 50.36%. Statistical differences in prevalence values among ranch and age groups were observed. Infections showed an over-dispersed distribution in each herd, as confirmed by very low K coefficients (0.001-0.01). Conclusions. Abundance values (EPG average) were mostly affected by the number of animals with a high parasitic burden rather than high prevalence values at each of the ranches. Most infections were not clinically relevant; animals with high parasite burdens were 1.75-28.56% of the total number of animals evaluated.