ILEAL AND TOTAL DIGESTIBILITY STUDIES IN PIGS FED MOLASSES TYPE-A OR STARCH DIETS SUPPLEMENTED WITH TORULA YEAST OR SOYBEAN-MEAL

A total of 48 pigs of -40 kg liveweight were used for digestibility studies with molasses Type A, molasses plus torula yeast or plus soybean meal, and cassava starch plus torula yeast. Half of the pigs were prepared with re-entrant cannulas in the terminal ileum and the other half were maintained intact for conventional digestibility studies. Nitrogen-free extract was found to be the main undigested fraction: 39% for molasses Type A and 52-67% for the remaining diets. The ileal digestibility of soluble carbohydrates in molasses diets was 96% which indicated that the undigested nitrogen-free extract fraction was mainly compounds of non-identified organic substances contained in molasses Type A. Energy disappearance in the large intestine accounted for 12% of that digested in the entire gastrointestinal tract in the case of molasses Type A and 18-20% in the other diets. Energy excretion in urine was significantly greater in molasses diets than in those containing starch, indicating a lower metabolizable to gross energy ratio in molasses diets than in starch diets (0.85 vs. 0.90). Digestible and metabolizable energy values for molasses Type A were 14.3 and 13.5 MJ kg-1 dry matter (DM) respectively, and for cassava starch diet 16.8 and 16.6 MJ kg- DM, respectively. According to the high ileal digestibility found in carbohydrates of molasses Type A, the low ileal and total digestibility of non-identified organic substances considerably reduced the dietary energy density, thus acting as an index for the nutritional value of molasses. © 1990.