Variability in rat weight gain during development

Abstract

The rat is one of the most employed animal models in biomedicine. Traditionally, weight gain has beenutilized to gauge development and compare across species. Numerous studies have conducted longitudinalanalyses of rat development, with emphasis on weight gain analysis. Given the high variability in thesepatterns, experimental data from a single laboratory may not be reliable for generalized estimation. Thisstudy aimed to analyze the effect of different factors on the pattern of weight gain during rat development.A literature survey was conducted to compile a database comprising nearly 300 data points of age and weightfrom 15 longitudinal studies. The database comprised both pre- and postnatal data. Utilizing the Gompertzequation, the data was analyzed to formulate a comprehensive model describing rat development.Differences in growth patterns became increasingly evident at later developmental stages, when significantdifferences in the maximum asymptote between sexes and strains were reached.