title: Some effects of sulphur intake on molybdenum metabolism in sheep.
abstract: 1. To investigate the effects of sulphur intake on molybdenum metabolism in sheep, ewes were given intakes of 0.3 or 3.5 mg Mo and 0.98, 1.33, 1.73 or 3.23 g S/d in a 2x4 factorial experiment with two replicates lasting 35 d. 99Mo with 0.1 mg carrier Mo was infused intravenously for the last 14 d and, when 99Mo concentrations in urine and faeces had attained plateaux (days 11-14), stable Mo and 99Mo balance trails were conducted; samples of blood and rumen contents were taken principally for studies of Mo distribution. 2. Increases in S intake caused the following changes in Mo metabolism; absorption decreased, urinary and faecal endogenous excretion decreased and retention increased; Mo concentrations in rumen contents decreased but the predominant association with the solid phase was unaffected; Mo concentrations in plasma decreased, but a higher proportion was associated with the protein fraction; Mo in protein-free plasma became apparently less ultrafiltrable at the glomerulus. 3. The pattern of response to S for each factor was generally curvilinear, the first increment in S intake having by far the greatest effect. The effect of S was generally greatest at the higher Mo intake. 4. It is suggested that the manifold effects of S on Mo metabolism are related to a common interaction in the rumen leading to the formation of Mo-complexes, possibly thiomolybdates, which are poorly absorbed but even more poorly excreted.
mesh_terms: D000818:Animals; D004032:Diet; D005243:Feces / Q000032:analysis; D005260:Female; D007408:Intestinal Absorption; D008982:Molybdenum / Q000378:metabolism*; D012417:Rumen / Q000378:metabolism; D012756:Sheep / Q000378:metabolism*; D013455:Sulfur / Q000378:metabolism*
chemical_list: D013455:Sulfur; D008982:Molybdenum