The primary objective of this research was to determine the effect of suppl
emental dietary silicon (Si) on plasma and milk Si concentrations of lactat
ing mares and the subsequent effect on plasma Si concentrations in nursing
foals. Additionally, the role of Si on altering biochemical markers of bone
turnover was investigated, because supplemental Si may be advantageous in
enhancing bone health. Twelve Arabian mare/foal units were pair-matched by
foaling date and randomly assigned to two groups, Si-supplemented (Suppleme
nted) or control (Control). Blood and milk samples were taken on d 0, 15, 3
0, and 45, d 0 being the 1st d after parturition. Plasma and milk (or colos
trum) Si concentrations were determined and serum was analyzed for osteocal
cin, carboxy-terminal pyridinoline cross-linked telopeptide region of type
I collagen, and pyridinoline and deoxypyridinoline crosslinks. All Suppleme
nted mares had higher (P < 0.01) plasma Si concentrations than Control by d
30, and Supplemented mares' milk had higher (P < 0.01) Si concentrations o
n d 45 than Control mares' milk. By d 45, foals of Supplemented mares had h
igher (P < 0.01) plasma Si concentrations than foals of Control mares. Supp
lemental Si did not influence (P > 0.36) bone metabolism in foals; however,
trends (P < 0.10) for altered bone metabolism were observed in postpartum
mares. Results indicate that supplemental Si increases plasma and milk Si c
oncentrations. Further research is required to determine whether Si has a r
ole in altering serum biochemical markers of bone and collagen activity.