Impact of high zinc oxide or lignocellulose supplement on fecal microbiota and growth performance of weaned pigs

The study conducted to evaluate the effects of high ZnO supplementation and lignocellulose fiber on microbiota, fecal inflammatory markers, and growth performance in weaned pigs. A total of 30 pens, each housing 5 piglets (6.39 ± 0.12 kg), were randomly allocated to 3 dietary treatments (10 experimental unit per treatment): Control (CON, 150 mg Zn/kg), ZO (CON + 2,500 mg Zn/kg), and LIGCEL (CON + 3% lignocellulose). The experimental diets (phase 1) were given for 14 d, followed by common diets in phases 2 and 3 for 2 additional 14-d periods. Growth performance was assessed, along with blood samples to analyze D-lactate, diamine oxidase (DAO), and fecal samples to calprotectin, neopterin, and microbiota composition. Blood and fecal samples were collected on d 7 and 14, and the effect of sampling time was evaluated. During phase 1, piglets in the ZO treatment showed a greater average daily gain and average daily feed intake compared to the CON treatment ( P < 0.05), while LIGCEL had intermediate values. Gain-to-feed ratio was greater for both ZO and LIGCEL compared to CON ( P =0.001 and 0.025, respectively). In phase 2, gain-to-feed ratio was lower for ZO and LIGCEL treatments compared to CON ( P = 0.008 and 0.049, respectively), while no differences were observed in phase 3. Across the overall experiment, average daily gain was greater in the ZO treatment compared to CON ( P = 0.014), with LIGCEL showing intermediate value. Blood D-lactate concentrations decreased while DAO increased from d 7 to 14 ( P = 0.001), with greater fecal DAO values in ZO treatment ( P = 0.001). Neopterin was greater in ZO piglets only on d 14 (Time × Treatment, P = 0.010), while calprotectin decreased over time but was unaffected by treatment ( P < 0.001). Microbiota analysis revealed that diet influenced the variation in microbial diversity, as estimated by beta diversity (R² = 0.20, P = 0.001). Lignocellulose treatment increased the abundance of Lactobacillaceae, ZO increased Lachnospiraceae and Prevotellaceae ( P adj < 0.001). Both ZO and LIGCEL improved growth and positively influenced the microbiota, indicating that lignocellulose fiber may represent a potential alternative to high ZnO concentration in weaned pig diets.