Morphometry of “Eimeria” oocysts in heifer calves according to age group and intensity of infection, municipality of Pirai, RJ

Abstract

The aim of this study was evaluate the average variation in the size of oocysts of Eimeria, recovered from heifer calves, using the following variables: age of the calves (0-100 and 101-180 days of age) and intensity of infection. In addition two measurements techniques were employed to correlate the morphometry of Eimeria species. A total of 1512 fecal samples were collected from 57 heifer calves in the municipality of Pirai, Rio de Janeiro, during the period August/2010 to June/2011, with 955 collected during the period 0-100 days and 557 from calves between 101-180 days old. Nine species of Eimeria were identified based on morphological and morphometric characteristics of oocysts and were present at the following percentages: E. ellipsoidalis (39.7%), E. alabamensis (18.4%), E. bovis (12.1%), E. zuernii (11.4%), E. subspherica (7.3%), E. cylindrica (6.0%), E. auburnensis (3.6%), E. wyomingensis (1.0%) and E. canadensis (0.6%). Calves up to 100 days old showed higher intensities of infection (%). Yet, in both age groups high intensity infection was the least frequently observed category of infection. Statistical analysis did not reveal any correlation (p> 0.05) between the two measurement techniques, indicating that they were equal effective. In the specific case of the oocysts of E. ellipsoidalis, it was observed that the age of the animals influenced oocyst morphometry as analyzed using either measurement techniques. However, no significant difference (p>0.05) in the morphometry of oocysts was observed in relation to the intensity of infection.