Sulphur metabolism in sheep. I. Preliminary investigations on the movement of sulphur in the sheep's body

Abstract

In a series of experiments with sheep maintained on high sulphur rations, measurements were made on the levels of 35S in urine, faeces, and various body fluids following single intravenous infusions of sodium [3%]sulphate and single infusions of sodium [35S]sulphate or sodium [353]sulphide into the gastrointestinal tract. Sulphide was rapidly absorbed from the duodenum and post-duodenal intestinal tract, an estimated 40–90% of the dose being absorbed within 60 min. Absorption of sulphate from the same region was much slower, 25% or less being absorbed over a 60-min interval. An attempt to use antibiotics to eliminate the effects of the intestinal bacteria on the metabolism of [35S]sulphate before absorption was not conclusive. Following intravenous administration of sodium [35S]sulphate, 12–19% of the dose was recovered in the faeces within 6 days. This activity appeared to be due to secretion into the post-ruminal tract rather than to return of 35S by salivary secretion or by passage across the rumen wall. Sodium [35S]sulphate was reduced to sulphide in the rumen and appreciable amounts appeared to be absorbed from this organ. The variations in total sulphur and sulphide of rumen digesta, urinary total sulphur, and blood inorganic sulphate levels during the day appeared to be related. Whole blood inorganic sulphate sulphur levels varied between 2 and 6 mg%. Urinary excretion following intravenous administration of 35S was extremely rapid, at least 70% of the dose being collected within 24 hr.