The development of products that slow the ruminal release of NH3-N without limiting the extent of urea
degradation in the rumen has been challenging. Owens et al. (1980) reported that ruminal NH3-N release was
slower for slow release urea product than for uncoated urea, thereby increasing diet acceptability and improving
rumen fermentation in ruminants. As reported that, supplementation of sugar cane tops (Saccharum offcinarum),
corn stubble (Zea mays) and King grass (Pennisetum purpureum) (high fiber diets) with controlled- release urea
supplement (CRUS) did improve fermentation in sheep (Puga et al., 2001) (Table 2). Adding 10, 20 or 30%
CRUS showed improved NH3-N and VFA production. This is strategies to improve the utilization of those
feeds, suggesting providing supplements to correct the nutrient imbalances for rumen bacteria (Nocek and
Russell, 1988). CRUS could have provided continuous NH3-N for microbial growth, superior the minimum of
15-30 mg NH3-N/100 ml rumen fluid for maximizing microbial growth previously suggested (Leng and Nolan,
1984).
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