Composition of Rumen Contents and Digestion as Related to the Type of Feed and Time of Sampling in Sheep

Ruminal digestion relative to the digestion in the remainder of the gastro-intestinal tract accounts for about 70 to 85% of the total digestion of dry matter (Annison, 1956). Phillipson (1958) showed that losses of digestible materials via absorption between the mouth and the duodenum were approximately 70% of that total. The interpretation of rumen composition and digestion data is complicated by several factors, such as dilution with materials remaining from previous feedings, inflow of saliva, variations in flow rate of the different nutrients and the time of sampling af ter feeding, (Yadava et al., 1964; Yadava and Bartley, 1964; Gray, Pilgrim and Weller, 1958a,b). The objectives of these experiments were to: 1. Determine the effects of the type of feed and the time of sampling after feeding on the concentration of selected nutrient fractions in the rumen; 2. Calculate the total digestion of the feed as determined by lignin vs. chromic oxide feed/feces ratios and; 3. Estimate the extent of total dry matter digestion accounted for by ruminal fermentation and absorption.