Some aspects of the pyridoxine (vitamin B 6 ) requirement in weanling piglets

Abstract

Four trials were carried out to determine the optimal level of dietary pyridoxine (vitamin B 6 ) and its interaction with riboflavin (vitamin B 2 ) in early-weaned piglets. In Trial 1, twelve piglets were tube-fed graded supplements of B 6 , 0, 10, 50 or 100 mg/kg. The level of 50 mg/kg maximized B 6 in red blood cells ( P <0·05). In Trial 2, thirty-six piglets were tube-fed with four combinations of B 6 (0 v . 50 mg/kg) and B 2 (0 v . 25 mg/kg). The B 6 supplement increased ( P <0·01) B 6 in red blood cells. C-peptide and insulin responses to intravenous glucose tended ( P <0·08) to or decreased ( P <0·03) with B 2 while no effect was observed on glucose. After gastro-enteral glucose, dietary B 2 depressed C-peptide and insulin responses in B 6 -unsupplemented piglets and increased them in B 6 -supplemented piglets ( P <0·03). The glucose response tended to be higher in B 6 -supplemented piglets ( P <0·06). Trials 3 and 4 were carried out in commercial conditions using either B 6 and/or B 2 supplements given during 2 weeks after weaning (Trial 3) or a B 6 supplement alone (50 mg/kg) given between 2 (weaning) and 10 weeks of age. Despite a marked and persistent increase ( P <0·01) of B 6 in red blood cells in B 6 -supplemented piglets, the effect on growth performance was either none ( P >0·39; Trial 3) or marginally lower ( <0·03; Trial 4). In conclusion, it appears that a dietary supplement of 50 mg/kg B 6 saturated the red blood cell pool in B 6 and influenced, along with B 2 , the glucose homeostasis through the entero-insular axis. Nevertheless, such metabolic effects are not reflected on growth performance.