The apparent retention of food in the reticulo-rumen at two levels of feeding by means of an hourly feeding technique.

I. Sheep fitted with rumen cannulas were fed at hourly intervals by an automatic feeder in a controlled environment and the contents of the reticulo-rumen were removed at intervals of 6 h, 30 min after the previous feed. 2. No diurnal variation was found in the total contents or in the quantity of dry matter, organic matter and nitrogen. 3. Nine dried pasture herbages containing 0.79-3‘69 yo N in dry matter were given automatically at a high and a low level of feeding. Feeding at the high level increased the total weight of the reticulo-rumen contents, total dry matter, organic matter and N and also the dry-matter percentage. 4. Apparent retention times were calculated by dividing the quantity of organic matter or N in the rumen by the quantity given each hour. Organic matter was retained for I O Z Z ~ . ~ h and N for 12.61.4 h. 5 . The apparent retention times for both organic matter and N were reduced when the level of feeding was raised.