First studies on a new concept for amino acid provision through B. subtilis in situ valine production in young pigs

Supplementation of crystalline amino acids is common in diets for piglets. The purpose of the present experiment was to conduct a study on an alternative amino acid provision by means of feeding piglets spores of a B. subtilis strain known to overproduce Val when cultured in vitro. Seventeen individually penned piglets per treatment were used. One week after weaning, piglets were fed one of 3 diets: a Val deficient (Val:Lys, 0.63:1; Neg), the same diet with added 1.28×106 cfu B. subtilis/g feed (+Bac), or a diet containing Val at requirement levels for piglets (Val:Lys, 0.69:1; +Val). During the 26-d feeding period, Val deficiency reduced (P<0.001) feed intake and growth rate of piglets, and supplementation of B. subtilis spores was not effective enough to compensate for the Val deficiency. Although there were some effects on mucosa, the dietary treatments did not have major effects on amino acid concentrations in digesta and mucosa of the small intestine. However, the Val concentration in plasma of the portal and jugular veins and the urea concentration in plasma of the jugular vein were higher when piglets were fed the +Val diet. The Val:Lys of 0.63:1 was clearly below the requirement of Val for piglets. The dietary supplementation of the B. subtilis strain that can overproduce Val, did not provide Val in levels high enough to compensate for a Val deficiency. Further investigations should focus on optimizing strains to greater Val overproduction in the gastrointestinal tract of pigs and establishing the optimal dose of B. subtilis supplementation.