This study aimed to evaluate the effects of dietary supplementation with probiotics (PRO), synbiotics (SYN), and SYN + benzoic acid (SYP) on growth performance, stress response, nutrient digestibility, blood parameters, immune status, and intestinal health of weanling pigs. Four hundred weaned pigs (Landrace × Yorkshire × Duroc) were allocated to four treatment groups: control (basal diet), PRO (Bacillus licheniformis), SYN (Bacillus licheniformis + dietary fiber), and SYP. The feeding trial lasted for 28 days. Notably, pigs in the SYN and SYP groups showed greater average daily gain during phase 1 (p = 0.038), phase 2 (p = 0.008), and the overall period (p = 0.011) compared with those in the control group. Gain-to-feed ratio was also improved during phase 2 (p = 0.003) and the overall experimental period (p = 0.012). The SYP group demonstrated significantly improved dry matter digestibility during phase 2 (p < 0.05). Serum IL-1β concentrations tended to decrease in pigs fed SYN and SYP diets. In addition, SYN and SYP supplementation increased the concentration of the tight junction protein zona occludens-1 (ZO-1) in the jejunum (p = 0.022). Histological analysis showed greater villus height in the duodenum (p = 0.013) and jejunum (p = 0.038) of pigs fed SYN and SYP diets. Overall, dietary supplementation with synbiotics, particularly in combination with benzoic acid, improved growth performance and intestinal health in weanling pigs.
Lee et al. (Wed,) studied this question.