Magnesium absorption from the large intestine of sheep
D.E. Dalley and A.R. Sykes
Animal and Veterinary Sciences Group, Lincoln College,
Canterbury
Proceedings of the New Zealand Society of Animal Production.
1989, 49: 229-232
Five mixed-age Coopworth ewes were offered a pelleted low Mg
(1.0 g Mg/kgDM) diet at the rate of 800 g/d for 2 months. Five levels
of MG (0, 0.5, 1, 2 and 4 g Mg/d) in 230 ml deionised water were infused
into the distal ileum for 48 h, followed by a recovery period of 24 h.
The treatments were randomly allocated to each animal using a latin
square design. Mg absorption from the large intestine was estimated
from changes in plasma Mg concentration and urinary Mg excretion rate.
Twelve h after commencement of infusion, plasma Mg concentration was
higher at 4 g Mg than at 0g. There was a positive relationship between
the amount of Mg infused and urinary Mg excretion. However, the
percentage of infused Mg that was absorbed declined from 18.2% to 6.9%
when Mg infusion rate was increased from 0.5 to 4 g Mg/d.
In a second experiment, using a cross-over design, increasing the amount
of water infused, with 4g Mg/d, from 230 to 2300 ml decreased urinary Mg
excretion.
The results show that Mg can be absorbed from the large intestine in
significant amounts and indicate that a passive transport mechanism may
be involved.
Keywords: NZSAPAB;
Absorption; infusion; large intestine; magnesium; passive; sheep
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Last Updated 18-03-1997
