There were no significant differences in BW between diet groups at any timepoint ( p > 0.05; t -test, Kruskal–Wallis tests; Table 2 ); however, BW on d14 approached significance ( p = 0.054; Kruskal–Wallis test), with CON pigs (11.61 kg) heavier than GXOS (10.94 kg) and XOS (10.92 kg) pigs.
In the present study, the absence of enhanced performance of prebiotic groups, as well as their near-significant reduction in BW on day 14, may reflect mismatches between substrate availability and microbial adaptation: in the sequential GXOS diet group, early GOS exposure may have primed communities that then required additional time to adjust to XOS, delaying microbial shifts and subsequent XOS-mediated performance benefits; conversely, in the XOS group, introducing XOS after seven days of the basal diet may have disrupted the stabilising microbial community, requiring a reorganisation of established cross-feeding networks and imposing short-term metabolic costs that limited growth efficiency.