Some effects of sulphur intake on molybdenum metabolism in sheep

Grace, N. D.; Suttle, N. F.

doi:10.1079/bjn19790019

Cited by 41 publications

(7 citation statements)

References 19 publications

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“…The results reported here demonstrate that the solid phase contributes a major part of the total amount of Cu, Mo, Zn and Fe in sheep rumen contents and this confirms similar findings by Durand & Kawashima (1979) and Grace & Suttle (1979). The association of these elements with the solid phase is due to their occurrence in plant material and adherent micro-organisms.…”

Section: Discussionsupporting

confidence: 79%

Involvement of the solid phase of rumen digesta in the interaction between copper, molybdenum and sulphur in sheep

Allen

Gawthorne

1987

Br J Nutr

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1. Merino sheep fed on a diet of chopped wheaten hay, chopped lucerne (Medicago saliva) hay and oat grain were the source of rumen contents for the study. The diet contained (mg/kg dry weight) 3.3 copper, 024 molybdenum and 2-8 sulphur. The effects of adding between 5 and 25 mg Mo/kg as ammonium molybdate (AM) or tetrathiomolybdate (TTM) on the distribution and forms of Cu and Mo in rumen contents were investigated in vivo and in vitro. 2.Approximately 88 YO of the Cu and 94% of the Mo in rumen contents were associated with the solid phase.When AM or TTM was added to rumen contents in vivo or in vitro the proportion of these elements in the solid phase was increased at the expense of the fluid phase.3. The addition of AM and TTM to rumen contents also decreased the proportion of Cu that was soluble in trichloroacetic acid (50 g/l ; TCA) and increased the proportion of Cu that was not extractable by sequential treatment with TCA and neutral detergent.4. Column chromatography of neutral-detergent extracts of rumen contents revealed that TTM treatment caused Cu to be strongly bound to proteins of high molecular weight.5. Addition of sulphide to rumen contents did not result in significant changes in the distribution of Cu between the fluid and solid phases, or in the solubility of Cu in TCA.6. It is postulated that constant removal of TTM from the fluid phase via reaction with proteins and other macromolecules in the solid phase results in greater formation of TTM in vivo than would be expected from solution chemistry. The molybdo-proteins so formed are strong chelators of Cu and may be the agents responsible for the decrease in Cu absorption in animals that consume diets containing high concentrations of Mo.When relatively high concentrations of molybdenum and sulphur are simultaneously present in the diet of ruminants the availability of copper to the animal is seriously compromised (Dick, 1956). The production of thiomolybdates in the rumen, and the subsequent decrease in the availability of Cu due to the formation of insoluble Cu thiomolybdates has been suggested as a hypothesis for the interaction (Dick et al. 1975). Confirmation of the hypothesis via spectrophotometric evidence of the presence of these compounds in rumen contents has been hampered by interference from other compounds, and by the low concentrations of Mo normally present. However, at moderately high molybdate concentrations, absorption spectra typical of thiomolybdates have been found in washed suspensions of rumen micro-organisms (Dick et al. 1975;El Gallad et al. 1983), in an artificial rumen apparatus (Bray et al. 1982), and in whole rumen contents (El Gallad et al. 1983), thereby indicating that the potential for thiomolybdate formation does exist .Interest has also centred on the particular species of thiomolybdates that may occur in vivo. Based on observations of solution chemistry, Clarke 8z Laurie (1980) concluded that tetrathiomolybdate (TTM) would not form unless the sulphide : Mo ratio was very high, and that at the lower ratios mor...

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Section: Discussionsupporting

confidence: 79%

Involvement of the solid phase of rumen digesta in the interaction between copper, molybdenum and sulphur in sheep

Allen

Gawthorne

1987

Br J Nutr

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“…2~ (Suttle, 1975) and probably due to the impairment of Mo absorption by S. The interaction may occur in the rumen or in the small intestine (Grace & Suttle, 1979). Provided that these soils released Mo in the rumen and not further down the alimentary tract, their inhibitory effects on Cu absorption from high S diets may have been due in part to a Cu x Mo x S antagonism in the rumen.…”

Section: Mechanisms For the Soil X Cu Antagonismmentioning

confidence: 99%

The role of a soil × dietary sulphur interaction in the impairment of copper absorption by ingested soil in sheep

1984

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SummaryFour repletion experiments were carried out to clarify the roles of molybdenum, sulphur and iron in the inhibition of copper absorption by ingested soils. In each experiment, groups of four to six hypocupraemic Scottish Blackface ewes were repleted for 21 days with diets containing CuSO4 and/or soil Cu and the responses in plasma Cu used to assess the availability of the Cu supplied.In Expts 1 and 2, three soils varying in Mo but high in Fe content and derived from Lower Lias Clay, Namurian Shale and Weald loam were added at 100 g/kg D.M. to diets of low (1·0) and high (4·1 g/kg D.M.) S contents: they provided 3·1, 2·8 and 0·1 mg Mo/kg D.M. respectively. When compared with groups given no soil, each soil increased plasma Cu repletion in the low S experiment and decreased it in the high S experiment. Inhibition was thus not completely dependent on soil Mo but dependent upon dietary S.Soils varying in Fe content were compared in the manner of the above experiments in Expts 3 and 4. Two Fe-rich soils, developed from the Upper Chalk and a Barton Clay and providing 2·8 and 1·5 g Fe/kg D.M., impaired Cu repletion on the high S diet but not on the low S diet. A soil, developed on a sand from the Bagshot Beds and providing only 0·15 g Fe/kg D.M., did not impair repletion but FeSO4, providing 0·8 g Fe/kg D.M. did so, irrespective of dietary S content. Ingestion of Fe-rich soils in a high S diet caused three-fold increases in rumen sulphide concentrations 5 and 24 h after feeding. It is suggested that soil ingestion impairs Cu absorption in sheep by trapping S as heavy metal sulphides such as FeS and releasing sulphide in the acid abomasum.

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“…Plasma samples were prepared by the method of Suttle (1974). The methods for determining Cu, Mo and S in diets are given by Grace and Suttle (1979). The methods for determining Cu, Mo and S in diets are given by Grace and Suttle (1979).…”

Section: Methodsmentioning

confidence: 99%

Retention of copper in the liver of sheep genetically selected for high and low concentrations of copper in plasma

et al. 1985

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The extent to which genetic selection to change the concentration of copper (Cu) in plasma also affected the retention of Cu in the liver was assessed in three experiments. In each, the concentration of Cu was measured in samples of liver (taken by biopsy) and of plasma from female sheep of lines selected from a Scottish Blackface x Welsh Mountain population (which had previously been interbred for several generations) for high and low plasma Cu levels (high line and low line) and from purebred Scottish Blackface and Welsh Mountain females.The concentration of Cu in the liver and plasma was found to be consistently greater in high-line and Welsh Mountain than in low-line and Scottish Blackface females (P < 0-01) in the first experiment in which grazing animals were sampled at both 6 and 10 months of age and in the second, where sampling' was at 6 months only. Mean Cu concentrations in the liver ranged from 13 to 115 mg/kg dry matter (DM) and the correlations with those in plasma varied from 0-28 to 0-53 (all P < 0-05) and was highest when the concentration of Cu in the liver was lowest. The correlation between the concentrations of Cu in liver at different ages was 0-57 (P < 0-05).In the third experiment, 10-month-old high-and low-line females were given complete diets containing either 5, 10, 22 or 28 mg Cu per kg DM for 12 weeks. Liver samples were obtained at the beginning and end of this period and blood samples were taken every 3 weeks. The concentration of Cu in the liver was greater in high-than in low-line sheep on all diets and increased linearly with the Cu concentration of the diet but at a greater rate in the high line. At the end, the high line had significantly greater concentrations of Cu in plasma on the 5 and 10 mg Cu per kg DM diets.The experiments showed that high-line females retained more Cu in the liver than low-line females. It is most likely that this was caused by a positive genetic correlation between concentration of Cu in plasma and the efficiency of absorption of Cu.

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Some effects of sulphur intake on molybdenum metabolism in sheep

Cited by 41 publications

References 19 publications

Involvement of the solid phase of rumen digesta in the interaction between copper, molybdenum and sulphur in sheep

Involvement of the solid phase of rumen digesta in the interaction between copper, molybdenum and sulphur in sheep

The role of a soil × dietary sulphur interaction in the impairment of copper absorption by ingested soil in sheep

Retention of copper in the liver of sheep genetically selected for high and low concentrations of copper in plasma

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