Measurement of the quantity and composition of digesta in the reticulo-rumen of sheep fed on a roughage diet

Abstract

In two experiments, estimates of the quantity and composition of digesta in the reticula-rumen of sheep given a roughage diet were made using a recently published marker technique. These estimates were compared with measurements made on the same sheep at slaughter. Estimates of digesta dry matter were influenced by the method of obtaining digesta samples from the rumen. When samples were withdrawn through a plastic tube, the resultant estimates underestimated the values obtained at slaughter by an average of 6%. An alternative sampling procedure is described which provided estimates within 1.5 % of values at slaughter. Values obtained for the organic matter, plant cell wall, and nitrogen content of digesta were similar for the slaughter method and the marker technique, irrespective of the method of sampling. In both experiments, the marker technique consistently underestimated the quantity of water in the rumen by 2-19 %. The importance of measures made on digesta load in the reticulo-rumen is illustrated by an examination of the variability between sheep in digestion of plant cell wall material.