PSX-B-16 Effects of Bacillus Subtilis Subsp. Subtilis Strain Atcc PTA-125135 Supplementation on Performance and Digestibility in Weaned Pigs

An experiment was conducted to evaluate the effects of supplemental Bacillus subtilis subsp. subtilis strain ATCC PTA-125135 on growth performance, feed efficiency, and feed digestibility in weaned pigs. Newly weaned pigs (n = 96) were randomly assigned to stacked-deck pens (n = 48) in two assemblies in adjacent rooms. Pens were randomly assigned within assembly to one of three treatments comprising control, S-0.25, or S-0.50. A common starter diet was fed for 10 days and then pigs were fed the assigned treatment for 17 days. The diets consisted of: 1) Control, a corn-soybean meal diet (1.30% total lysine, chromium dioxide as marker); 2) S-0.25 (control diet with addition of 0.25 g per kg supplement in feed; 3) S-0.50 (control diet with addition of 0.50 g per kg supplement in feed), where supplement comprised 8.1 × 10⁸ CFU g^-1 of Bacillus subtilis PTA-125135. Body weights and feed disappearance were collected on d 0, d 7 and 14 of supplementation. Feed digestibility was measured by total collection of feces from d 14-17. Data were analyzed by ANOVA with main effects of treatment and room. Contrasts were used to compare means of microbial supplementation with control. Pig performance did not differ from d 0-7. During d 8-14, body-weight gain was not affected, but feed intake was decreased by approximately 6.0 percent (P = 0.147), and G:F was improved by approximately 10.6 percent (P = 0.106). Apparent feed digestibility did not differ among groups (P = 0.507), but total digested dry matter was less for treated groups (P = 0.163), which reflects reduced recorded dry matter intake. The changes observed from week 1 to week 2 indicate a transition was occurring with microbial supplementation resulting in improved utilization. These results indicate that supplementation of B. subtilis PTA-125135 improved feed efficiency. Supplementation duration should be considered for future evaluations.