Sulfur and methionine metabolism in sheep. IV. Metabolism and absorption in the intestines.

Twelve 18-month-old Merino wethers were fed a ground and pelleted diet of equal parts oaten chaff and lucerne chaff. Sulfur flows at the ileum and faecal excretion of sulfur were estimated for two levels of dry matter intake (500 and 1000 g/day) in sheep receiving intraruminal infusions of water or 4.5 g DL-methionine per day. Increasing dry matter intake from 500 to 1000 g/day resulted in greater flows of total sulfur from 660 to 1183 mg/day in the ileum; protein sulfate increased correspondingly from 312 to 585 mg and non-protein organic sulfur rose from 324 to 497 mg; DL-methionine infusions had no effect. The 1000-g level of intake increased the excretion of all faecal sulfur components compared to those of sheep receiving 500 g dry matter; the amino acid supplement increased total, neutral and total reducible sulfur excretion only at the 500-g level of dry matter intake. The apparent digestibility of sulfur in the small intestine ranged from 36 to 44%, while apparent digestibility between the proximal duodenum and anus ranged from 59 to 66%. Most of this digestion was due to a reduction in organic sulfur in digesta during flow through the intestines.