Fiabilité des mesures de poids et d'examens histopathologiques dans les études d'intoxication du campagnol des champs (Microtus pennsylvanicus)

Abstract

The values of body weight and internal organ weights as indices of the antinutritive properties of certain plants in the diet of meadow voles (Microtus pennsylvanicus) was determined by comparing these measures to results obtained by histological sections of liver and kidney. The white clover (Trifolium repens) diet is the only one to have caused kidney lesions, but diets of timothy (Phleum pratense), reed phalaris (Phalaris arundinacea), simple aster (Aster simplex) or Canada thistle (Cirsium arvense) had considerable effects on the liver. Voles fed ground ivy (Glecoma hederacea) or umbellate aster (Aster umbellatus) had lesions characteristic of periportal interstitial hepatitis that normally results from an irritation. Histological analyses suggested that 10 of the 12 experimental diets had had detrimental effects on the animals, whereas measures of body or organ weight had identified only 7 of the diets; 5 of these corresponded to the diets found in a previous analysis. We therefore conclude that measurements of weight alone are insufficient and should be combined with the results of histopathological examinations in studies on antinutritive properties of plants in the diet of meadow voles.