Rice Polishings as a Supplement in Sugar Cane Diets: the Quantities of Starch ( -linked Glucose Polymers) Entering the Proximal Duodenum

3 Zebu cross steers each fitted with a permanent rumen fistula and a T piece cannula in the proximal duodenum, were used in a 3 x 3 Latin square design experiment to determine the quantities of alpha linked glucose polymers entering the small intestine, when fed a diet of chopped sugar cane plus 1 kg/d of molasses containing 30 g urea/ kg with levels of rice polishings of 0.4, 0.8 and 1.2 kg/d. Each experimental period lasted for 3 weeks, at the end of which rumen dilution rates and duodenal dry matter flows (kg/24 hr) were measured using polyethylene glycol and chromium-EDTA respectively. Rumen ammonia-N levels were low at all times throughout the experiment and there were no significant differences between treatments. There was a tendency to increase both rumen turnover and outflow with increased quantities of supplement in the diet. Values for rumen turnover were 1.36, 1.51 and 1.99, and rumen outflow (litres/ day) 82, 115 and 123, corresponding to levels or supplementation of 0.4, 0.8 and 1.2 kg/d. No significant differences were found in the quantities. of dry matter, organic matter and total nitrogen entering the small intestine (g/24 hr) due to the level of supplement in the feed. There were however significant between treatment differences in both the concentration (g/100 g DM) and quantity (g/24 hr) of alpha linked polymers entering the small intestine due to the level of rice polishings in the diet. Increasing the level of supplementation from 0.4, 0.8 to 1.2 kg/d resulted in increased concentration of the alpha linked polymers in the duodenal digesta viz 9.7, 13.1 and 20.0 (g/100 g DM). Corresponding quantities per 24 hr were 288, 464 and 765.