EFFECTS OF VARIATION IN SOLUBLE CARBOHYDRATE INTAKE ON SULFUR DYNAMICS IN THE SHEEP RUMEN

Two groups of experiments were conducted (named the 15 % starch and 30 % starch intake experiments) to examine the effects of dietary energy levels on the synthesis of ruminal microbial protein and the absorption of sulfur from the rumen. The level of energy intake affected the absorption rate of sulfide from the rumen, the net microbial protein flow rate, the amount of microbial protein synthesized per kg organic matter 'truly digested' in the rumen and the daily flow of recycled sulfur. For the 15 % starch and 30 % starch intake experiments the absorption of sulfur from the rumen was 1.207 and 1.278 g day-1 absorbed from 2.298 and 2.212 g intake, respectively, the flow of microbial protein was 80.2 and 92.1 g day-1, respectively, and the estimated recycled sulfur was 0.357 and 0-670 g day-1, respectively. It was estimated that 18.1 and 20.1 g of microbial protein was synthesized per 100 g of organic matter 'truly digested' in the rumen for 15 % starch and 30 % starch diets, respectively.