<![CDATA[Utilizing feed, as source of protein is generally expensive, therefore efforts are carried out over come this problem i.e. using non-protein nitrogen like urea. Urea as a source of nitrogen for rumen microbe. The contribution of microbial protein rumen to the amino acid require• ment of ruminant livestock can reach 40 to 80 %. The success in triggering the growth rate of ruminal microbe will have a great influence on the fulfillment of amino acid needs of livestock. The experiment was aimed to evaluate the effect of sweet potato-urea complex prod• uct properly to the ration of Holstein Friesian Bull Calves during the growth period on rumen metabolism parameters. The rumen metabolism parameters were pH, J\TH3, Total Volatile Fatty Acids (TVFA), Dry Matter Digestibility Coefficient (DMDC), Organic Matter Digestibility Coefficient (OMDC), and Microbial Protein Synthesis (MPS). Randomized block design was applied to arrange the experiment. The sweet potato-urea complex with the level of 0, 15, 30, and 45 % of the concentrate as treatments were used in this experiment. Sixteen growing Holstein Friesian Bull Calves of 6 months old were divided into four groups based on body weight. The results of the in vivo experiment showed that ruminal ammonia concen• tration and microbial protein synthesis were significantly (P<0.01) affected by treatment. Ammonia concentration were 7.99, 10.50, 14.75, a~d 18.67 mM, and microbial protein syn• thesis were 788.4, 896.7, I 087 .0, and 764.3 mg.hr , respectively for the sweet potato-urea complex level of 0, 15, 30, and 45 %. DMDC and OMDC were significantly (P<0.05) af• fected by the treatment, while the sweet potato-urea complex level did not significantly affect TVFA. The average DMDC and OMDC were 63.54, 68.56, 71.00, 74.28 and 64.86, 68.01. 70.38, 74.29, respectively, for 0, IS, 30 and 45 % level, whereas, TVFA between 129.20 - 147.70 mM.]]>
