all ADC (one value per tank) a simple linear model was used, including the treatments as fixed factor. The data were assumed to be normally distributed and to be homoscedastic, based on a graphical residual analysis. Analyses of variances (ANOVA) and multiple contrast tests (e.g.: Bretz et al., 2011) were conducted in order to compare the treatment effects. Effects of sampling method or diet on the ADCs were conducted via 2-way ANOVA. All other parameters were analyzed via 1-way ANOVA. P ≤ 0.05 was defined as the level of significance.
The lower and the upper critical concentrations, plateau and slopes were classified by ±standard error (s.e.). All remaining data are presented as arithmetic mean values ± standard deviation (s.d.).