## 3 Results  
Live BW increased from \(55\pm 5\) kg at 99 days of age to \(110\pm 11\) kg at 154 days. The ADFI increased from \(2.4\pm 0.4\) kg/day to \(3.3\pm 0.5\) kg/day between the beginning and the end of the trial. Due to illness, some animals had to be removed from the experiment. Furthermore, some fecal samples could not be collected from some animals at one time point. At the end of the experiment, 513 fecal samples from 143 pigs had been sequenced for microbiota analysis (Figure S2). The number of sequences ranged from 15,752 to 80,731 (21,156 \(\pm\) 12,226 sequences on average). All the samples were kept for further statistical analysis. After filtration for the rare OTU under 0.01% relative abundance, 1556 OTU remained. According to Wilcoxon tests applied on control and challenged female pigs at 119 and at 140 days of age, the DON challenge did not significantly impact the number of OTU, the Shannon index, or the relative abundance of the main phyla (\(p>0.05\)) (Table S2). Following this result, we chose to group all female pigs (control and challenged) to evaluate the impact of the age on microbiota composition. The richness and Shannon index of the fecal microbial community increased between post-weaning and finishing stages (\(p<0.05\)), and remained stable during the finishing stage from 99 to 154 days (Table 1). The relative abundance of Firmicutes increased between 52 and 99 days (\(p<0.05\)), and a stability was achieved from day 99. The relative abundance of Bacteroidetes decreased all over the trial (\(p<0.05\)). The relative abundance of Spirochaetes increased and the relative abundance of Actinobacteria decreased during the finishing stage (\(p<0.05\)). The main represented family among the samples was Lactobacillusacea. The abundance of Lactobacillusae (mainly _Lactobacillus_), Lachnospiraceae, Ruminococcaceae and Veillonellaceae decreased between 52 to 119 days, and were stable afterward. The abundance of Prevotellaceae (mainly _Prevotella_) decreased between 52 and 99 days, was stable between 99 and 140 days, and decreased at the end of the trial. The abundance of Streptococcusaceae (mainly _Streptococcus_) increased between 52 and 99 days, decreased between 99 and 119 days, and was stable afterward. The _Clostridium sensu strictio_ relative abundance increased between 52 and 99 days, was stable between 99 and 140 days, and increased at the end of the trial, in contrast with the _Prevotella_ relative abundance (Figure 1). Based on the control samples, the structure of the bacterial community evolved across ages but the dispersion at each age remained homogenous (\(p=0.09\)). The NMDS grouped the samples according to the age (Figure S3) and this separation was confirmed using the MANOVA (FDR \(<0.05\) for each pairwise comparison). Microbiota composition clustered into two enterotypes at 52 days of age, named post-weaning enterotype 1 (PWE1) and post-weaning enterotype 2 (PWE2) (Figure 2a and Figure S4). The microbial diversity in PWE1 was lower compared to PWE2 according to the number of OTU (\(2605\pm 313\) vs. \(2953\pm 258\), \(p<0.001\)), as was the Shannon index (\(6.60\pm 0.19\) vs. \(6.76\pm 0.16\), \(p<0.05\)). The PWE1 enterotype was dominated by _Prevotella_, _Sarcina_, _Treponema_, _Dialister_, _Mitsuokella_, _Clostridium sensu strictio_, _Fusicatenibacter_, _Roseburia_, _Blauttia_, _Eubacterium_, _Enterococcus_, and _Desulfovibrio_ (\(p<0.05\)), whereas _Lactobacillus_ and _Megasphaera_ were more abundant in the PWE2 enterotype (Table S3). The ADG, ADFI, and FCR between 99 and 154 days of age did not differ between the enterotypes at 52 days.