Categorical data measured only once were analyzed using the Fisher's exact test (2-sided) . Count data were analyzed using the Mann Whitney U test. For comparison of body weight development we fitted a linear model for weight using time and group as covariates. Litter size was also tested as a covariate but no significant effect was observed and it was removed from the model. The interaction between time and treatment was included in the model so each treatment would have its own growth rate. We also considered a spline at day 23 (weaning threshold). The spline allows the growth rate to change after the day 23 for each treatment. This way we are able to test differences of the growth rate between treatments before and after weaning. The model was fitted using generalized estimation equations (GEE) with compound symmetry for the working correlation matrix because of the repeated measurements for weight. The comparisons of the average growth rates between the three groups were computed using the covariance matrix of the model coefficients. The data was analyzed using SPSS version 16 