Digestion of concentrate and of hay diets in the stomach and intestines of ruminants

Abstract

I. The flow of digesta to the abomasum and through the duodenum and terminal ileum was measured over 24 h periods in sheep. Pelleted diets of concentrates, principally composed of barley, and of poor-quality hay were given. The seven Scottish Blackface ewes studied were all fitted with rumen cannulas, and in addition two had simple abomasal cannulas, one a re-entrant abomasal cannula, two re-entrant duodenal cannulas, and two re-entrant ileal cannulas.2. Paper impregnated with chromium sesquioxide was given twice daily by rumen fistula. The amounts of dry matter, starch, cellulose, total nitrogen and energy passing through the abomasum, duodenum and ileum and the amounts excreted in the faeces were measured.Thc flows of digesta were adjusted to give 100 % recovery of chromium sesquioxide and the extent of digestion in various parts of the alimentary tract was calculated using these adjusted values. Concentrations of glucose in the blood and of volatile fatty acids (VFA) in the rumen were also measured.3. For the concentrate diet, 69 yo of the digestible dry matter disappeared in the stomach (reticulo-rumen, omasum and abomasum), 17 % in the small intestine and 14 % in the large intestine. Values for disappearance of digestible energy were 7 2 % in the stomach, 23 Yo in the small intestine and 5 % in the large intestine. Of the 298 g starch fed daily only 6-35 g passed through the abomasum or duodenum and only 1-4 g reached the terminal ileum. The cellulose in the diet was poorly digested. 4.For the hay diet, 67 % of the digestible dry matter disappeared in the stomach, 7.2 % in the small intestine and I I yo in the large intestine. Values for disappearance of digestible energy were 81 yo in the stomach, 7 yo in the small intestine and 12 yo in the large intestine.Of the 33 g of starch consumed daily, from 5 to 13 g passed through the abomasum or duodenum. The cellulose in the hay was 59 % digestible and virtually all this digestion took place in the stomach.5. The concentration of VFA and the proportion of propionate in the rumen fluid, 2.5 h after feeding, were considerably greater on the concentrate diet than on the hay diet, but diet had little influence on the concentration of blood glucose.6 . The importance of the small amount of starch passing to the sheep's small intestine is discussed.The volume and composition of the digesta passing through various sections of the digestive tract of sheep can be measured directly by causing the digesta to flow through re-entrant cannulas inserted into either the duodenum or terminal ileum (

Polysaccharide synthesis and degradation by rumen micro-organismsin vitro

“…Assuming a 10 1. turnover of rumen fluid in 24 h, less than 7 g of microbial starch would pass into the abomasum and intestines. This is in broad agreement with the estimates of Heald (1951), Weller & Gray (1954), MacRae & Armstrong (1969) and Topps, Kay & Goodall (1968). A small portion of this, about 10 %, could be contributed by the protozoa.…”

The effect of cold exposure of sheep on digestion, rumen turnover time and efficiency of microbial synthesis

“…For pelleted diets, the digestion of readily fermentable dietary material may be essentially complete in the rumen (Topps, Kay & Goodall, 1968). However, the extent of digestion of structural material may be dependent on the rate of passage of digesta through the rumen (Thomson, 1972).…”

Quantitative microbial protein synthesis in the bovine rumen

“…Similar results were obtained by Harris and Phillipson (1962); Bruce e^ al. (1966); and Topp, Kay and Goodall (1968). This indicates that collection procedures used in these experiments tended to depress flow rate slightly.…”