Transport of valine across the small intestinal epithelium in pigs fed different valine levels and Bacillus subtilis

Mutants of Bacillus subtilis overproducing valine (B. subtilis VAL ) could be an approach to supply pigs dietary valine (Val). In the study, 18 gilts were fed: (i) negative diet with a standardized ileal digestible (SID ) Val:Lys of 0.63:1 (Neg); (ii) Neg added B. subtilis VAL (1.28 × 10¹¹ cfu/kg as‐fed) or; (iii) Neg added L‐Val to a Val:Lys of 0.69:1. Using the Ussing chamber method, the study aimed to investigate whether (i) the diets affect intestinal transport of additions of 0, 5, 10 or 20 mmol Val/L from the mucosal to the serosal side and (ii) the B. subtilis VAL contributes to a net transport of Val produced in situ. The results showed that the Isc (ΔIsc_Val) and release of Val to the serosal side solution (S_rel; μmol cm^?2 min^?1) increased with Val addition (linear and quadratic, p  <  .0001) but was similar for 5, 10 or 20 mmol Val/L and not affected by diet. No net transport of in situ produced Val by B. subtilis VAL was detected. In conclusion, feeding a Val‐deficient diet with or without B. subtilis VAL or a Val sufficient diet did not affect the Val transport across intestinal epithelia. No in situ Val production by B. subtilis VAL was observed in the Ussing chambers.