Resumen

MORALES, Gustavo et al. Levels of parasitic infection, body condition, and haematocrit values in resistant, resilient, and wormy animals in a Criollo Rio Limon cattle herd. Zootecnia Trop. [online]. 2006, vol.24, n.3, pp.333-346. ISSN 0798-7269.

At the INIA experimental station in Ciudad Bolivia, Barinas; Venezuela, an experiment was carried out to evaluate the effect of strongylids infestation levels on body conditions and haematocrit values. Forty two animals of the Rio Limon cattle breed were examined. The number of parasite eggs per gram (epg) of feces was established by the McMaster technique and microhaematocrit centrifugation technique was used for haematocrit values determination. The body condition was evaluated according to the scale method with scores varying from 1 to 5 (1 = emaciated; 5= excessively fat). The color of the ocular conjunctivae membrane was scored in five categories (1= red; 5= white). Cattle with a good body condition (>3), normal or almost normal haematocrit value and high epg.counts were classified as resilients, but when the animals had a body conditions <2.5, a low haematocrit value and high epg counts, they were classified as wormy animals. The results of the present work were the following: No relationship was observed between the ocular conjunctivae color and the hematocrit value. Of 42 evaluated cattle, 34 (80%), 4 (9.5%) and 4 (9.5%) were classified as resistant, resilient, and wormy animals, respectively. The wormy and resilient animals had higher epidemiological importance because they are the strongest polluters of the pasture and constitute the target group to be drenched, but the absence of relationships between the visual conditions and the infestation level indicate that the only and safe way to select the target fraction within the herd is the quantitative coprological exam.

Palabras clave : parasitosis; bovine; hematocrit; resilience; resistance.