Evaluation of the background for determination of vitamin requirements in pigs

Influence of pre-, pro-, and synbiotics on the intestinal availability of different B-vitamins

This study was conducted with 16 male growing pigs (eight pigs with an end-to-end ileo-rectal anastomosis, eight intact pigs) to investigate in metabolic trials the influence of different pre-, pro-, and synbiotics on the precaecal and faecal digestibility of thiamin, riboflavin, pantothenic acid and biotin. A basic experimental diet was supplemented with either pre-, pro-, or synbiotic additives as follows: lactulose (2%), inulin (2%), mannanoligosaccharides (0.3%), Enterococcus faecium DSM 10663 (8 x 10(9) cfu/kg), Enterococcusfaecium DSM 7134 (5 x 10(8) cfu/kg), inulin + Enterococcusfaecium DSM 10663, mannanoligosaccharides + Enterococcus faecium DSM 7134. The precaecal and faecal digestibilities of the investigated B-vitamins were not affected significantly by the administered pre-, pro-, and synbiotics independent of the application period. A higher faecal vitamin excretion vs. the precaecal indicated that thiamin and biotin were synthesized in the colon. On the contrary, for riboflavin and pantothenic acid a higher precaecal vitamin flow compared to the faecal excretion was detected indicating to a certain extent an absorption in the colon.

Biotin supply by large bowel bacteria in minipigs: evidence from intracaecal avidin

The influence of a change of colonic availability of biotin on biotin status was studied. This was done by inhibition of biotin absorption by intracaecal avidin infusion. Five adult minipigs with a permanent caecal 'T' cannula were fed on a semi-synthetic, biotin-deficient diet for 4 months. Following an 8-week adaptation period there were nine sequential 1-week infusion periods with or without oral lactulose or antibiotics. Avidin infusion during weeks 2, 5 and 8 amounted to 18 mg/d (13 U/mg). Plasma biotin concentrations were not changed by avidin infusions. There was a significant average 84% rise in faecal biotin excretion during the avidin periods. Urinary biotin output following avidin decreased by 21%. This is taken as evidence that biotin synthesized by colonic bacteria is available for host metabolism. A rough estimate shows that under basal conditions 1.7-17% of the metabolic allowance may be covered by this metabolic route.

Biotin studies in pigs. 3. Biotin absorption and synthesis

Eight pigs were given a semi-purified diet based on maize flour and casein containing 10 micrograms biotin/kg. The diet was given ad lib. with or without a supplement of 70 micrograms biotin/kg diet from 5 to 94 d of age. The flow of biotin in the stomach was similar to the biotin intake (13.5 and 112 micrograms/d) for the unsupplemented and biotin-supplemented pigs respectively. The flow of biotin through the small intestine decreased for the biotin-supplemented pigs from 39 micrograms/d in the first quarter of the small intestine to 7.9 micrograms/d in the last quarter. The flows of biotin in the caecum, large intestine and colon were similar for both the unsupplemented and biotin-supplemented pigs, with values of 17-54 micrograms/d, indicating the synthesis of biotin in the hind-gut.