THE EFFECT OF REPLACEMENT OF WHEAT BRAN BY GRADED-LEVELS OF MOLASSES ON FEED-INTAKE, ORGANIC-MATTER DIGESTION, RUMEN FERMENTATION AND NITROGEN-UTILIZATION IN CROSSBRED (BOS-TAURUS X BOS-INDICUS) STEERS FED NATIVE GRASS HAY

This 4 x 4 Latin square experiment evaluated the effect of replacement of wheat bran by graded levels of sugar cane molasses on feed intake, rumen fermentation and nitrogen utilization. Four ruminally fistulate d crossbred (Bos taurus x Bos indicus) steers were given a basal diet of grass hay ad libitum and 4.0 kg dry matter of wheat bran day-1 (Die t MO). In the other three diets wheat bran was replaced with 1.0 (Diet ML), 2.0 (Diet MM), or 3.0 kg dry matter of molasses (Diet MH). Urea supplementation was used to make the three diets (ML, MM and MH) isoni trogenous with the basal diet (MO). The voluntary dry matter intake of hay (mean 4.01 kg, standard error of the means 0.128) was not affecte d significantly (P > 0.05) by the treatments. The apparent digestibili ty of organic matter was similar between diets. Molasses did not depre ss significantly (P > 0.05) the average value of rumen pH. Increasing the level of molasses increased mainly the molar proportion of propion ate at the expense of acetate (P < 0.05). Apparent digestibility of ni trogen was similar between diets (P > 0.05). Daily excretion of allant oin in the urine was not affected (P > 0.05) by molasses. There was a quadratic (P < 0.05) effect caused by molasses so that with Diets ML a nd MM the daily excretion of uric acid was higher compared with the tw o other diets. Total microbial purine derivatives (allantoin plus uric acid) and microbial nitrogen were not significantly (P > 0.05) differ ent between diets.