Sheep Stomach Research Articles

Digestion of a ground and pelleted diet in the stomach and intestines of young sheep from two breeds

Some aspects of digestion were studied in small groups of fistulated wether lambs from two breeds, Dorset Horn and Corriedale. The Iambs were given a ground and pelleted diet of equal parts hay and concentrates once daily at two levels of intake. At the same liveweight (25 kg), the higher intake was associated with reduced digestion of organic matter (OM) and fibre in the whole gastro-intestinal tract; rumen mean retention times were also reduced, as was the proportion of OM digestion which occurred in the rumen. An increase in the amount of protein entering the intestines appeared to be composed of both undegraded dietary protein and microbial protein. Despite a reduction in the digestibility of non-ammonia nitrogen in the intestines, more crude protein was digested there per unit of digestible OM intake (25.9 v..23.6%; P < 0.05). Differences between the breed groups were smaller than those associated with level of feeding. Nevertheless, particularly at lower relative intakes, rumen mean retention times were longer, rumen digesta content was greater, and rumen OM and fibre digestion tended to be greater in the Dorset Horn lambs; crude protein digestion in the intestines per unit of digestible OM intake also tended to be less at the low intakes. More than three-quarters of the cellulose digestion but less than half the hemicellulose digestion occurred in the rumen. The proportion of the urea synthesized that was degraded in the gastrointestinal tract (0.24-0.30) was consistently lower in these lambs than has been reported for adult sheep.

Simulation of the effects of rumen function on the flow of nutrients from the stomach of sheep: Part 1—Description of a computer program

A computer program to simulate rumen function in sheep is described. It predicts the degradation of dietary components within the rumen, products of fermentation, microbial growth yields and the flow of protein and other materials from the rumen. Input information includes: feed intake; modulus of fineness of the diet, chemical composition of the diet in terms of β-hexose, α-hexose, soluble carbohydrates, true protein, non-protein nitrogen, total fatty acids, inorganic sulphur and ash; potential degradability of β-hexose and protein; factors indicating the fractional reduction in maximum rate of degradation of β-hexose, α-hexose and protein due to chemical and physical properties of the diet; and time spent feeding and ruminating. Inflow to the rumen of protein, non-protein nitrogen and inorganic sulphur in saliva is predicted, and the amount of each salivary and dietary substrate degraded in the rumen, flowing intact from the rumen or accumulating within the rumen is assessed. Adenosine triphosphate (ATP) released during fermentation is used for maintenance of the existing microbial mass. If ATP release is insufficient a portion of the microbial mass is catabolised, otherwise microbial growth can occur and some degraded substrates are incorporated directly into microbial protoplasm. Possible limits to microbial growth from an insufficiency of amino acids, ammonia, total nitrogen or inorganic sulphur are assessed, and the change in rumen microbial population is determined from the difference between growth and outflow of micro-organisms. Predictions from the program are shown to be stable and to respond appropriately to changes in intake and composition of the diet.

Simulation of the effects of rumen function of the flow of nutrients from the stomach of sheep: Part 2—Assessment of computer predictions

The adequacy of the concepts and of the quantitative information incorporated into a computer program which simulates rumen function in sheep has been assessed by observing the sensitivity of the predictions to changes in variables requiring better numerical description and by comparing the predictions with observations made for different dietary situations. For all diets, the predicted amount of total protein flowing from the rumen was highly sensitive to changes in the potential degradability of dietary protein, the fractional outflow rates from the rumen of water and of microbes, and the energy required for maintenance of the microbial population. For diets in which nitrogen limited microbial growth, it was also highly sensitive to changes in salivary flow, which represents the recycling of nitrogen to the rumen, and to the proportion of rumen ammonia available for microbial growth. For all diets, the predicted outflow of total protein from the rumen showed medium sensitivity to changes in the composition of microbial organic matter; for high fibre diets, it showed medium sensitivity to changes in the potential degradability of β-hexose; and for diets high in starch, it showed medium sensitivity to changes in the fractional outflow rate of α-hexase. For diets in which inorganic sulphur availability limited microbial growth, the model predictions showed medium sensitivity to the proportion of rumen inorganic sulphur available to the microbes. Because these variables could not be set with confidence, it is clear that research is needed for their better definition. For many dietary situations the pattern of the response in model predictions closely followed that of experimental observations. However, the inability to predict the effects of increasing rumen solute load, grinding and pelleting of forages or the recycling of endogenous nitrogen when microbial growth was limited by nitrogen availability, emphasises the need for research in these areas.

The use of markers to measure digesta flow from the stomach of sheep fed once daily

SummaryTwo methods for calculating the flow of digesta and its constituents from the concentrations of two markers, 51Cr-labelled chromium EDTA (51Cr-EDTA) and 103Ru-labelled ruthenium phenanthroline (103Ru-P), and digesta composition were compared in fistulated sheep fed once daily and in other fistulated sheep fed continuously. One method uses the marker concentrations to calculate the flow of whole digesta directly (double-marker) whereas the other uses the markers to calculate separately the flow of fluid and non-filtrable particles, the sum of which is digesta flow (two-marker).When feed was given continuously, flow values calculated using the double-marker method and the two-marker method, which requires a correction to be made for nonideal behaviour of 51Cr-EDTA, did not differ. When feed was given once daily, the double-marker method consistently overestimated flow relative to the corrected twomarker method but the differences were extremely small (less than 0-8% for digesta flow and 0-5% for nitrogen flow). 51Cr-EDTA as a single marker slightly overestimated digesta flow (up to 2·3%) but grossly overestimated nitrogen flow (up to 22·5%); 103Ru-P as a single marker grossly underestimated both digesta flow (up to 30·5 %) and nitrogen flow (up to 23·1%).It was concluded that the double-marker method is to be preferred when the diet is given continuously or frequently at fixed intervals. When the diet is given once daily, the two- and double-marker methods can be expected to give similar values. Single markers should not be used for estimating the flow of digesta and its constituents when samples are taken from a simple cannula.

The digestion of nitrogen associated with plant cell wall in the stomach and small intestine of the sheep

The digestion of dietary cell wall constituents was estimated during measurements of the passage of digesta from the stomach and intestines of sheep. Two groups of four sheep were used, and they were fed on either mature wheaten hay at 600 g/d or immature dried ryegrass at 800 g/d. Cell wall constituents comprised c. 58.7% and 39.8% of the organic matter in the two diets, while the nitrogen associated with cell wall was equivalent respectively to 14.1 and 24.6 % of dietary nitrogen. With wheaten hay, 45 % of cell wall organic matter and 25 % of cell wall nitrogen were digested in the stomach. The corresponding values for ryegrass were, respectively, 81 and 89 %. The nitrogen in cell wall contributed about 9% of non-ammonia nitrogen in digesta leaving the stomach and 15 % in digesta leaving the ileum with wheaten hay, but only 4-5 % at each site with ryegrass. Although the release of amino acids from cell wall in the small intestine was less than from the remaining crude protein in digesta, it was concluded that the amounts involved were too small to have much effect on the apparent release of amino acids in digesta passing through the small intestine.

A radioimmunoassay for the measurement of blood group Ii activities: Its application to glycoconjugates, oligosaccharides and intact cells

A double antibody radioimmunoassay has been developed for the blood group Ii antigens using radioiodinated I-active sheep stomach glycoproteins, an Ii-active extract from human meconium, and sera from patients with cold agglutinin disease. The radioimmunoassay has been used to study the expression of Ii antigens in human ovarian cyst glycoproteins with and without blood group A, B, H and Lewis activities, and it has revealed the presence of I and i activities in several glycoproteins not previously detected by quantitative precipitation assays. Precursor-like glycoproteins from individuals who were non-secretors of ABH antigens showed the highest I and i activities. Certain of the ABH active glycoproteins from secretors showed no I or i activities, while others showed weak or moderate I and i activities, suggesting that they contained unsubstituted precursorlike oligosaccharide chains. Hapten inhibition studies with anti-I Ma have shown that the radioimmunoassay requires approximately 35 times less oligosaccharide inhibitors than inhibition of precipitation assay. The radioimmunoassay has been applied to the investigation of the I and i activities of very small quantities of glycosphingolipids. The assay has also been applied to the measurement of the Ii antigens on intact human erythrocytes and on erythrocytes after treatment with pepsin or neuraminidase.

The effects of nitrilotriacetic acid on solubilities of zinc, copper, manganese, and iron in the stomach of sheep.

Four sheep, each prepared with a rumen fistula and reetrant cannula in the proximal duodenum, were used to study the effects of ruminal administration of nitrilotriacetic acid on solubilities of zinc, copper, manganese, and iron in rumen and duodenal digesta. The sheep received a pelleted diet and were dosed with 0, 300, 600 and 1200 microgram of nitrilotriacetic acid per gram of diet via the rumen fistula. Higher concentration of soluble zinc, manganese, and iron but not copper, were found in the rumen of the sheep when they were dosed with nitrilotriacetic acid. The concentrations increased with increasing dose of the acid. However, only the solubilty of iron was increased in the duodenal digesta. Concentrations of soluble zinc and manganese in the rumen increased, whereas copper decreased, during the first 2 h after feeding. The pattern was reversed thereafter. Changes in the concentrations of soluble during 6 h afther feeding were comparatively small. It is concluded that the solubilty of iron in the stomach of sheep is increased by ruminal administration of nitrilotriacetic acid.

Sulfur and Methionine Metabolism in Sheep. II. Quantitative Estimates of Sulfur Metabolism in the Sheep's Stomach

The metabolism of dietary and supplemental DL-methionine sulfur in the stomach of sheep was studied in two experiments. In both experiments sheep were fed a 50 : 50 oaten chaff: lucerne chaff ration at two levels of intake, and some animals received intraruminal infusions of DL-methionine. In experiment 2 increasing dry matter intake (DMI) increased first approximations of total, neutral, protein and reducible sulfur flows and also sulfide sulfur flow from the reticulo-rumen. Increased DMI (from 500 to 1000 g/day) also resulted in greater true flows of total (2207 v. 1104 mg/day), neutral (1867 v. 1043 mg/day) and protein (893 v. 482 mg/day) sulfur at the duodenum. Two flow diagrams of sulfur metabolism in the compartments of the ruminant stomach were developed from the data of experiment 2. Fluid flows of sulfur in experiment 1 were used to supplement the data of experiment 2 in developing the balance models. The two models represent the extremes of dietary and supplemental sulfur metabolism in the sheep's stomach under the conditions of experiment 2, and they are discussed in relation to previous research on sulfur metabolism in the stomach.

Behaviour of solute and particle markers in the stomach of sheep given a concentrate diet.

1. Fistulated sheep given a concentrate diet were used to study the behaviour of solute ([51Cr]EDTA) and particle ([103Ru]phenanthroline) markers in the stomach under conditions of continuous feeding. 2. An injection of a mixed dose of [51Cr]EDTA and [103Ru]phenanthroline was given into the rumen and the time course of marker concentrations in the rumen and the abomasum was recorded. The curves were analysed on the assumption that the stomach of the sheep could be represented as two mixing compartments (reticulo-rumen and abomasum) and a time delay (omasum). This model provided a very good description of the data. 3. [103Ru]phenanthroline associated with small particles was retained in the rumen much longer than [Cr]EDTA. Although exchange of [103Ru]phenanthroline occurred between large and small particle fractions, the results suggested that small particles may have been retained somewhat longer in the rumen than solutes. However, it was clear from the results that the mean retention times for particulate matter in the rumen could not be simply obtained using adsorbable markers. 4. Cyclical fluctuations in the concentration of [51Cr]EDTA in the rumen indicated that there were daily variations in net water flux in the rumen. 5. The presence of protozoa was associated with much shorter retention times of both solutes and particles in the rumen. Protozoa were also associated with reduced rumen volumes.

Digestion in the stomach and intestines of sheep receiving diets of red clover silage with various supplements

AbstractThree castrated male sheep fitted with rumen and duodenal re‐entrant cannulae were used in a 3×3 Latin Square experiment to investigate the digestion of three diets of red clover silage with supplementary concentrates containing barley or barley and groundnut meal or barley and urea. The supplements were designed to be isocaloric and the groundnut meal and barley‐urea mixtures to be isonitrogenous.There were no significant (P >0.05) differences between treatments in the digestibility of organic matter (mean value 71.2%) or in the percentage of dietary organic matter digested in the stomach (mean value 53.6%) and diiferences between treatments in the concentrations of total and individual short‐chain fatty acids in the rumen were small. The nitrogen intake for the barley treatment was 19.41 g/d and that for the groundnut meal and barley‐urea treatments were 23.36 g/d and 23.05 g/d respectively. Corresponding figures for the duodenal flows of nitrogen were 21.97 g/d, 21.48 g/d and 21.14 g/d and for the faecal losses of nitrogen were 7.09 g/d, 6.98 g/d and 6.92 g/d. As a consequence, although the diets supplied quite different amounts of digestible crude protein they supplied similar amounts of crude protein digested in the intestines.

The absorption of magnesium from the forestomachs, stomach and small intestine of sheep

The passage of magnesium from the mouth to the proximal duodenum and from the proximal duodenum to the terminal ileum was measured continuously in two rams for 24 and 19 days. The results indicate a net disappearance of 25 per cent and 34 per cent of ingested magnesium from the forestomachs and stomach, and no set absorption from the small intestine.

Effect of high intakes of sodium chloride on the utilization of a protein concentrate by sheep. II.* Digestion and absorption of organic matter and electrolytes

The effects of the ingestion of large amounts of sodium chloride (c. 150 g/day) on digestion and absorption were examined in sheep offered a diet consisting of 89% linseed meal. Although water intake was increased by only 2 litres per day, the rate of flow of fluid from the rumen and digesta from the abomasum increased by 5–6 kg/day and the mean residence time of a soluble marker was reduced from 20 hr to 12 hr. Digestion of organic matter in the stomach was reduced by c. 24% but the reduction in protein digestion was only 10%. The concentrations of protozoa and selenomonads in the rumen were reduced by the salt treatment. Approximately 50% of the ingested sodium and chloride was absorbed from the stomach in sheep on the high salt diet, although levels of sodium and chloride in the rumen did not exceed those in the plasma. Osmotic pressures in the stomach fluids and in the plasma were elevated by the salt treatment, although levels of sodium in plasma were unaffected. Plasma chloride and potassium levels were both increased by the salt treatment. *Part I, Aust. J. Agric. Res., 26: 709 (1975)

The digestion of fatty acids in the stomach and intestines of sheep given widely different rations

SummaryThe amounts of total lipid and fatty acids consumed, leaving the stomach and excreted in the faeces were examined in 4 sheep fitted with rumen and re-entrant duodenal cannulas. Diets of high (HM1) and low (CM1) roughage content were given at 0·9 times maintenance and the low-roughage diet was also given at 1·7 and 2·3 times maintenance. With all the rations more fatty acid left the abomasum than was consumed in the food, the difference being greater on ration CM1 than on ration HM1 and increasing irregularly with the amount of the low-roughage ration fed. Of the fatty acid entering the duodenum in the chyme, 72–89% was digested in the intestine. About 80% of the increase in fatty acids in the stomach was stearic acid and most of the remainder was palmitic acid. Almost all the polyunsaturated C18acids ingested in the food were hydrogenated in the stomach, and the amounts of oleic acid were also greatly reduced, although more oleic acid entered the duodenum in the chyme with ration CM1 than with ration HM1. The possible origins of the increase in fatty acids in the stomach are discussed.

Production and absorption of ammonia in the sheep's stomach.

1. When rumen fluid together with small quantities of (15NH4)2S04[1-14C]sodium acetate and polyethylene glycol (PEG) was introduced into the emptied rumen of a sheep, no significan change occurred in the ratio15N:14C during a period of 30–60 min. The ratio15N:PEG, however, declined by 22–53%. when(15NH4)2SO4, [1-14C]sodium acetate and PEG were introduced into the normal rumen of a sheep fed on lucerne hay the ratio15N:14C in the whole rumen contents showed no appreciable change in a period of 1 h, but the ratio15N:PEG declined by 25–41%. It was therefore concluded that the rate constants for removal of ammonia nitrogen (NH2-N) and volatile fatty acid (VFA) from the rumen were very nearly equal.2. In sheep fed at 1 h intervals on lucerne hay chaff or lucerne hay pellets VFA production, VFA and NH3-N concentration in the rumen fluid and the volume of fluid passed from the rumen to the omasum were determined. From these results and the information previously gained on the relative rates of removal of NH2-N and VFA from the rumen, the amounts of NH3-N produced in the rumen and absorbed there or at lower levels of the digestive tract were calculated to be equivalent to 23–27% of the dietary N in lucerne hay chaff and 17% of that in lucerne hay pellets; 59–66% of the NH3-N was absorbed from the rumen and the remainder passed to the omasum.

The effect of diet composition and level of feeding on digestion in the stomach and intestines of sheep.

1. Four wether sheep, each fitted with re-entrant duodenal cannulas and a rumen cannula, were used to determine the relative quantitative importance of digestion in the stomach compared with that in the intestines when diets of low (HM1) and high starch (CM1) content were fed at 0.9 times maintenance and when the high-starch diet was fed at 1.7 (CM2) and 2.3 (CM3) times maintenance. Paper, impregnated with chromic oxide, and polyethylene glycol (PEG) were administered.2. An apparatus is described which allowed one operator to collect, record, sample and return the duodenal digesta from two sheep simultaneously.3. Total digestion was determined by faeces collections over 7–10 day periods, and digestion in the stomach by measuring the total flow of digesta from the abomasum to the duodenum over two 24 h periods with two or three sheep on each ration. Flow values were adjusted to give 100% recovery of chromic oxide.4. The recoveries of chromic oxide and PEG were similar and it was concluded that either marker was satisfactory for adjusting 24 h flow values. Disadvantages of using PEG are discussed.5. There was relatively little difference between rations HM1 and CM1 in the proportion of digestible organic matter and energy digested in the stomach. Only 57.1% of the total dry-matter digestion occurred in the stomach for ration HM1 compared with 65.0% for ration CM1 reflecting a smaller net gain in ash for ration CM1. Doubling the level of intake (ration CM2) resulted in a decrease in the proportion of digestible dry matter, organic matter and energy digested in the stomach. When the level was increased still further with ration CM3, the proportion continued to decrease with one sheep but increased with the other.6. All but 5–11% of the digestible starch (measured as α-linked glucose polymer) was fermented in the stomach, the lowest proportion being with ration HM1.7. The amount of nitrogen reaching the duodenum was approximately equal to the amount ingested with rations HM1 and CM1 but considerably greater with the other two rations. All rations contained approximately 2% nitrogen.8. Calculation of the estimated loss of energy as methane and heat of fermentation suggested that 50–54% of the digestible energy was absorbed as volatile fatty acids.

On the areas of the stomach of sheep that are sensitive to formic acid and histamine

1. The infusion into the rumen via a cannula of 11. of aqueous solutions containing formic acid and/or histamine had no influence on the time sheep took to eat their food offered immediately after the infusion.2. The infusion of formic acid solutions containing histamine into the rumen via stomach tube had variable effects when the length of stomach tube introduced was random. When they were introduced through 72 cm of stomach tube (measured from the incisor teeth), so that the end of the tube was at the cardia, one sheep consistently refused food or ate only a little but another sheep was only occasionally affected in this way.3. Solutions marked with phenol red passed rapidly to the abomasum when introduced into the region of the cardia via a stomach tube. Only insignificant quantities of phenol red were detected within the same time in the abomasum when the solution was introduced into the rumen via a rumen cannula.

The plants eaten by sheep and by Kangaroos grazing together in a paddock in South-western Queensland

It has been found possible to identify plants and to estimate their relative proportions by volume in the stomachs of sheep and kangaroos (both the red and the grey species). The method involves grinding stomach contents to a fine powder and isolation of particles of a given size range by differential sieving. It is shown that kangaroos are reasonably sedentary so that comparison of the botanical composition of the stomach of free-roving kangaroos with those of sheep restricted to one area, is valid. The three species of herbivore, during the study period of 1 yr and under the conditions described, were found to have food preferences. These preferences were specific enough to justify the conclusion that the plants of the habitat and the three species of animals constitute an ecosystem. There is no evidence, pound for pound body weight, that kangaroos eat more than sheep. Large numbers of kangaroos could have a detrimental effect on wool production since they eat considerable quantities of dicotyledons which are rich in protein and which constitute about 50% of the sheep's intake. Kangaroos, although ostensibly adapted for browsing, never ate mulga or berrigan. Sheep, however, browsed both these trees.

SOME IMMUNOLOGIC ASPECTS OF PARASITIC HELMINTH INFECTIONS.

Studies on the host-parasite relationship of the sheep stomach worm, Haemonchus contortus suggest that important antigens which are involved in the stimulation of immunologic resistance are released during growth and development of the parasite as it penetrates, molts, and matures in the host. These antigens seem to be released and made available to the host for only short periods of time and in some instances may be present for only a few minutes. Because nematodes do not undergo multiplication in host tissues and because the rate of acquisition of parasites and their subsequent development in the host is irregular, it is difficult regularly to elicit good levels of immunologic resistance by infection procedures which utilize normal or attenuated infective larvae. The recent development of techniques for in vitro maintenance and cultivation of various parasitic stages of the parasite provide a means for collecting antigens elaborated during growth and ecdysis. Results with these materials give hope that it might be feasible to induce an immune resistance response by vaccination which in some cases may be better than that resulting flora natural infection.

The Distribution of Histamine in the Sheep Stomach

SUMMARY The histamine content and distribution of mast cells in the tissues of the sheep's stomach has been studied. The abomasum contained more histamine than did any other compartment. There was no significant difference between the histamine content of reticulum, rumen and omasum. In the abomasum, histamine was mainly in the mucosa and in greater concentration in the body than at the pylorus. Histamine and mast cell ‘profiles’ have been constructed for the mucosa of body and pyloric regions of the abomasum. The distribution of histamine in the former region was closely related to the number of mast cells present. There was evidence of non-mast cell histamine in the pyloric mucosa. The concentration of histamine decreased progressively from duodenum to colon.

Differentiation of the Sheep Stomach Worms Teladorsagia davtiani (Andreeva and Satubaldin, 1954) and Ostertagia trifurcata (Ransom, 1907)

SUMMARY The sheep stomach worms Teladorsagia davtiani and Ostertagia trifurcata are briefly described. Illustrations are provided to facilitate differentiation of these 2 species.