Analysis of Rodent Growth Data in Toxicology Studies

Abstract

To evaluate compound-related effects on the growth of rodents, body weight and food consumption data are commonly collected either weekly or biweekly in toxicology studies. Body weight gain, food consumption relative to body weight, and efficiency of food utilization can be derived from body weight and food consumption for each animal in an attempt to better understand the compound-related effects. These five parameters are commonly analyzed in toxicology studies for each sex using a one-factor analysis of variance (ANOVA) at each collection point. The objective of this manuscript is to present an alternative approach to the evaluation of compound-related effects on body weight and food consumption data from both subchronic and chronic rodent toxicology studies. This approach is to perform a repeated-measures ANOVA on a selected set of parameters and analysis intervals. Compared with a standard one-factor ANOVA, this approach uses a statistical analysis method that has greater power and reduces the number of false-positive claims, and consequently provides a succinct yet comprehensive summary of the compound-related effects. Data from a mouse carcinogenicity study are included to illustrate this repeated-measures ANOVA approach to analyzing growth data in contrast with the one-factor ANOVA approach.

The effects of cigarette exposure on rat salivary proteins and salivary glands

“…The total amount of chow eaten over the 31‐day experimental period by one rat was calculated as the dairy food consumption per rat. To account for the difference in body weights of the CS‐exposed vs control animals, relative food consumption was also calculated by dividing the weight of food eaten by the weight of the animal and expressed as gram of food consumption per 100 g of the mean of daily rat body weight during the experimental period (Hoffman et al , 2002). The amount of drinking was also measured and calculated.…”

Effects of chronic deoxynivalenol exposure on p53 heterozygous and p53 homozygous mice

“…Multiple group comparisons of non-parametric data were conducted using the Kruskal-Wallis ANOVA on Ranks, followed by post-hoc pairwise comparisons using the Dunn's method. Animal weights and relative food consumption (food consumption/bw) were analysed by ANOVA on weekly average weights (Hoffman et al, 2002). Comparisons of data from p53þ/þ and p53þ/À mice were conducted by Two-Way ANOVA to identify interactions between strain and dose, followed by post-hoc pairwise comparisons using the Holm-Sidak method.…”

Sexual Maturation in Common Vole (<I>Microtus arvalis</I>) Males Raised under Laboratory Conditions

“…In our experiment, the lowest body mass was observed in 4 week-old males, while the highest in 10 week-old males; 6 and 8 week-old male body weights were comparable. We assume that adult common vole body weight will not change with time, as in other mature rodents (HOFFMAN et al 2002). Furthermore, in mammals, the quality and …”