author(s)
Mamata Joysowal, AK Tyagi, Nitin Tyagi, Sachin Kumar, Anchal Keshri and Digvijay Singh

abstract
Ruminant have an unique physiological ability to utilize Nonprotein nitrogen substance in diet. Dietary protein is required to provide amino acid and nitrogen sources for microbial protein synthesis and body requirement. During sacristy period and to reduce the cost of diet the use of NPN substances (urea & their products) is helpful for dairy farmers. The use of urea in the ruminant diet is most accepted because of its low cost compared with other NPN source and availability; mostly protein feeds such as soybean meal are highly rumen degradable. There are many factors which need to be understood before approaching to utilize NPN substance in animal feeding. Addition of urea in diets is limited due to its rapid hydrolysis to ammonia-nitrogen in the rumen by urease enzyme resulting in rapid accumulation and escape of ammonia- nitrogen from the rumen. Slow rumen released nitrogen compound primary stem because of its potentiality for slow ammonia release just after post feeding thereby decreasing peak ammonia concentrations in the rumen that lead to its inefficient utilization by ruminal microorganisms and increased absorption from the rumen, which would also reduce the metabolic cost and ammonia poisoning. This review describes the utilization of slow release urea for a dairy animal in favor of ruminal fermentation and lactation performance.