Magnesium absorption in mature ewes infused intrarumenally with magnesium chloride

McLean, A. F.; Buchan, William; Scott, D.

doi:10.1079/bjn19840120

Cited by 7 publications

(4 citation statements)

References 12 publications

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“…PEG was used as a marker for estimating digesta flow. Nearly all (> 95%) of the total magnesium in the digesta of the abomasum was found to be in the liquid phase which agrees with data from the literature (McLean, Buchan & Scott, 1984;Ben-Ghedalia et al 1975). Consequently, the flow of magnesium has been evaluated from the magnesium concentration multiplied by the liquid flow rate of the abomasum.…”

Section: Flow Of Digestasupporting

confidence: 85%

Effects of low sodium intake on magnesium metabolism of sheep

Martens¹,

Kubel²,

Gäbel³

et al. 1987

J. Agric. Sci.

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Three sheep, equipped with cannulae in the dorsal rumen sac, abomasum and ileum, were fed a low sodium diet of artifically dried young grass. Mean daily intake of sodium was 310 mg. The sheep were given daily supplements of 0 or 2'3 g sodium by an intraruminal infusion.The concentration of K in mixed saliva and ruminal fluid from the sheep not given sodium supplements increased and the concentration of Na decreased markedly. The changes in the ion concentrations were associated with an increase of the transmural potential difference across the ruminal epithelium.The altered ion concentrations of Na and K in the ruminal fluid and the increased potential difference were accompanied by a decrease in Mg absorption from the forestomachs. The apparent availability of Mg from the gastrointestinal tract decreased from 34-5 (sodium supplementation) to 22-3 (low sodium intake).It is suggested that a daily intake of Na of 310 mg did not cover the sodium requirement of these sheep and that a low sodium intake influences the absorption of Mg in a similar manner as it has been observed with a high K intake.The results are discussed in context of grass tetany in ruminants. It is suggested that an inadequate intake of sodium is an overlooked factor of the pathogenesis of this disease.

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Section: Flow Of Digestasupporting

confidence: 85%

Effects of low sodium intake on magnesium metabolism of sheep

Martens¹,

Kubel²,

Gäbel³

et al. 1987

J. Agric. Sci.

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“…Conversely, as more dietary Mg is absorbed in the forestomachs the concentration of Mg in colonic digesta is reduced and the quantity of Mg absorbed in the hindgut decreases. This hypothesis suggested by these model results is consistent with the experimental observations of McLean et al (1984) and Dalley et al (1997). In fact, an inspection of the model results presented in Table 8 of the current'paper compare favourably with the experimental resuits of Table 2 of Dalley et al (1997).…”

Section: Model Challengesupporting

confidence: 90%

“…The results of the model including absorption from the hindgut, with kHgPl set at 2-5, are represented in Table 8 in the same format as previously, and indicate much closer agreement between the model and the unpublished results of Dingwall and Field. That absorption occurs in the hindgut has been observed by several other workers (Tomas & Potter, 1976b;McLean et al 1984) whose data are not shown by Grace (1983).…”

Section: Model Challengementioning

confidence: 50%

“…Other workers have observed at least 0.4 g Mg/d being absorbed from the rumen alone. McLean et al (1984) measured up to 0.6 g/d being absorbed proximal to the pylorus in a balance trial and Martens & Blume (1986) observed 0-7 1 mmoVh (0.4 g/d) being absorbed from a rumen using the washed rumen technique where the observed potential difference was 26.1 mV.…”

Section: Effect Of Changes In Vkp (Moum2 Per D ) On Faecal and Urimentioning

confidence: 96%

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A model of magnesium metabolism in young sheep. Magnesium absorption and excretion

et al. 1997

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A model of Mg metabolism in sheep is proposed. It is based on standard Michaelis-Menten enzyme kinetics to describe the transport of Mg across the rumen wall and passive diffusion to describe the absorption of Mg in the hindgut. Factors known to have an effect on Mg metabolism in farm animals, namely the concentrations of K and Mg in the diet, and the physico-chemical conditions within the rumen as determined by the type of diet, are incorporated into the model. Consideration of the rumen as the only site of Mg absorption provided an inadequate mechanistic description of Mg metabolism in sheep. To ensure compatibility between predicted Mg absorption and recent independent data sets for Mg balances, it was necessary to include in the model aspects of Mg absorption that operate in the hindgut. The results from this model suggest that there is a need for a series of experiments to determine the important aspects of Mg transport in the hindgut of sheep.Mechanisms pf homeostasis are discussed.

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Impaired absorption of magnesium in theaetiology of grass tetany

Dua

Care

1995

British Veterinary Journal

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Magnesium absorption in mature ewes infused intrarumenally with magnesium chloride

Cited by 7 publications

References 12 publications

Effects of low sodium intake on magnesium metabolism of sheep

Effects of low sodium intake on magnesium metabolism of sheep

A model of magnesium metabolism in young sheep. Magnesium absorption and excretion

Impaired absorption of magnesium in theaetiology of grass tetany

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