Growth curve and morphometric variables in rats: are they related?

Four growth curve variables were measured in a population of rats in order to assess their association, if any, with a suite of morphometric characters. The growth curve variables (A = asymptotic weight, R = growth rate, P = percentage of asymptotic size at inflection, and G = time to grow from 10 to 90% of asymptotic size) were derived from Richards' curves applied to longitudinal body weight data, and the morphometric characters (measured in 189-day-old rats) consisted of 4 tooth and 7 bone variables. As assessed by a canonical correlation analysis, there was a significant association between the two sets of variables, especially between A and the skeletal variables. It was hypothesized that associations of the bone characters should be greater with A but less with R compared with those for the tooth characters, and this was shown to be the case. The canonical correlation analysis also showed a strong association of P with G in each sex, although in a factor analysis these two variables associated with R.