The Role Of Volatile Fatty Acids and The Antibiotics in Improving Sheep Utilization of Urea Nitrogen

The successful use NPN in stimulating the consumption of poor quality roughges by ruminants is evident especially when coupled with a source for readily available carbohydrates . Therefore, it enables ruminants to retain more nitrogen which used for growth,foetus development and milk production . Efficient utilization of dietary urea depends primarily upon the rate of its hydrolysis as well as the rate of ammonia uptake by rumen microbes of that released from the hydrolysed urea . Usually the rate of ammnia release exceeds considerably the rate of uptake (Bloomfield et. al., 1960) resulting in laryo losses of nitrogen in the urine . Much efforts were concentrated on controlling the rate of urea ingestion to the rumen to avoid ammonia accummlation . The most effective methods are either to add high level of salt in a block containing urea (Messenger et al, 1971) or molasses when urea presented in the drinking water ( Abou El- Nasr, 1979). Of the other dietary addatives which seemed to improve urea utilization, trace elements, antibiotics and branched chain volatile fatty acids occupied on advanced position .The present study was carried out to evaluate two methods for urea suppl ementationthese were urea - salt mixlure or urea dissolved in the drinking water.