Published online by Cambridge University Press: 08 March 2007
Four trials were carried out to determine the optimal level of dietary pyridoxine (vitamin B6) and its interaction with riboflavin (vitamin B2) in early-weaned piglets. In Trial 1, twelve piglets were tube-fed graded supplements of B6, 0, 10, 50 or 100 mg/kg. The level of 50 mg/kg maximized B6 in red blood cells (P<0·05). In Trial 2, thirty-six piglets were tube-fed with four combinations of B6 (0 v. 50 mg/kg) and B2 (0 v. 25 mg/kg). The B6 supplement increased (P<0·01) B6 in red blood cells. C-peptide and insulin responses to intravenous glucose tended (P<0·08) to or decreased (P<0·03) with B2 while no effect was observed on glucose. After gastro-enteral glucose, dietary B2 depressed C-peptide and insulin responses in B6-unsupplemented piglets and increased them in B6-supplemented piglets (P<0·03). The glucose response tended to be higher in B6-supplemented piglets (P<0·06). Trials 3 and 4 were carried out in commercial conditions using either B6 and/or B2 supplements given during 2 weeks after weaning (Trial 3) or a B6 supplement alone (50 mg/kg) given between 2 (weaning) and 10 weeks of age. Despite a marked and persistent increase (P<0·01) of B6 in red blood cells in B6-supplemented piglets, the effect on growth performance was either none (P>0·39; Trial 3) or marginally lower (<−2 %; P<0·03; Trial 4). In conclusion, it appears that a dietary supplement of 50 mg/kg B6 saturated the red blood cell pool in B6 and influenced, along with B2, the glucose homeostasis through the entero-insular axis. Nevertheless, such metabolic effects are not reflected on growth performance.