Re-entrant Cannulas Research Articles

Comparison of ileorectal anastomosis and the conventional method for the measurement of ileal digestibility of protein sources and mixed diets in growing pigs

Apparent digestibility determined by collection of digesta at the terminal ileum has been shown to provide a reliable estimate of amino acid availability in pigs. As a routine technique for collecting ileal digesta, ileorectal anastomosis (IRA) has been proposed. In this trial, twelve Yorkshire × Chinese Black Pigs (45 kg) were used to compare IRA with the ileocaecal re-entrant cannula (IC) method, which was considered as a reference cannula technique. Three complex diets—a soyabean meal diet (SBMD), a rapeseed meal diet (RSMD), a Chinese common commercial diet (CCCD)—and three simple diets—a fish meal (Peru) diet (FM), a raw soyabean diet (RSB) and a single cell protein (SCP) diet—were used. The trial was conducted as a 6 × 6 Latin square design. The results show that, with the exception of the dry matter in SBMD and RSMD, organic matter in SBMD and CCCD, and valine, glutamic acid and analine in CCCD, similar values for dry matter, organic matter, energy, crude protein and amino acid digestibility were obtained in IRA and IC pigs on the six diets. Regression coefficients showed a close relationship between IRA and IC ( P < 0.01) of the apparent digestibility of nutrients, except for dry matter, organic matter and serine ( P < 0.05). There were no significant differences in growth and development between the IRA and intact pigs. In general, apparent digestibility of nutrients in FM was the highest and the complex diets had a higher digestibility of crude protein and amino acids than RSB and SCP. The digestibility of nutrients was almost equal between RSB and SCP.

Comparison of 0.9, 3.6, and 7.2% NaCl for correction of experimentally induced hypochloremic, hypokalemic metabolic alkalosis in sheep

Summary Nine adult female sheep were each surgically fitted with an Ivan and Johnston reentrant cannula in the cranial part of the duodenum just distal to the pylorus. By diversion (loss) of abomasal outflow, this model has been shown to consistently induce hypochloremic, hypokalemic metabolic alkalosis, accompanied by hyponatremia and dehydration. Each sheep was subjected to 3 treatment trials, each preceded by a 24-hour prediversion period, and a diversion period during which a syndrome of hypochloremia (68 ± 2 mEq/L), hypokalemia, hyponatremia, and metabolic alkalosis was induced. Development of this syndrome was attributable to losses of large amounts of acid and electrolytes in the abomasal effluent. Mean total electrolyte contents of the effluent were: Cl−, 650 ± 27 mEq; Na+, 388 ± 23 mEq; and K+, 123 ± 12 mEq, with total volume loss ranging from 3.6 to 10.0 L of gastric contents and pH ranging from 3 to 5. Decreases in plasma electrolyte concentrations also can be attributed to decreased intake, because anorexia developed shortly after the onset of diversion. Electrolyte losses in urine during diversion were minimal for Cl− (mean ± sem, 12.0 ± 5.1 mEq), but were greater for Na+ (124.2 ± 14.5 mEq) and K+ (185.1 ± 31.2 mEq). Treatments consisted of 0.9% NaCl (300 mosm/L), 3.6% NaCl (1,200 mosm/L), and 7.2% NaCl (2,400 mosm/L) administered over a 2-hour period, with the administered volume determined by the estimated total extracellular fluid Cl− deficit. Significant difference was not found among treatments, with all solutions resulting in return of clinicopathologic and physical variables to prediversion values within 12 hours of treatment. We concluded that rapid iv replacement of Cl−, with small volumes of hypertonic saline solution, is safe and effective for correction of experimentally induced hypochloremic, hypokalemic, metabolic alkalosis in sheep.

Whey protein digestion in the distal ileum of the preruminant calf

Ileal digestion of three milk replacers containing either total milk protein or a mixture (50 : 50 on a crude protein basis) of total milk protein and native or heated whey protein concentrate was studied in six preruminant calves fitted with ileo-caecal re-entrant cannulas. Ileal digesta were collected for 4 days. Apparent nitrogen digestibility was significantly lower for the diets containing native or heated whey proteins than for the control (0.89, 0.90 and 0.92, respectively). Digestibility was also lower for most amino acids (AA), and especially for glutamic acid, proline and glycine, but tended to be higher for cystine. Replacement of the control diet by the whey diets resulted in slight but significant changes in the proportions of aspartic acid, leucine, tyrosine, histidine and arginine in the digesta. In contrast, treatment of whey protein did not alter the AA composition of the digesta. Iterative comparisons of AA profiles suggested that the major part of the protein escaping digestion in the small intestine for all diets was of endogenous origin. However, for the whey diets, a small peptide resulting from whey protein hydrolysis could constitute an important part of the undigested protein present in the whey digesta in comparison with the control digesta. This suggested that some whey fractions were probably not totally digested in the intestine. In conclusion, moderate heat treatment had no pronounced effect on whey protein digestion, and whey protein seemed to be satisfactorily digested in the small intestine of the preruminant calf.

The digestion process of the sugar alcohol isomalt in the intestinal tract of the pig

In a study with ten pigs of 60-70 kg live weight, provided with a re-entrant cannula at the end of the ileum, and sixteen intact, non-cannulated pigs, the digestion and absorption of a dietary dose of 100 g isomalt/kg, and isomalt given between the meals as a 'sweet' on the basis of 50 and 100 g/kg feed consumption, were examined. In all three isomalt treatments slightly less than 0.40 of the isomalt consumed was digested in the small intestine when the calculations were based on ileal sugar passage. However, when basing the calculations on energy contents of ileal chyme, only approximately 0.10 was digested in the small intestine. The bacterial fermentation of the isomalt flowing into the large intestine was indicated by a decreased faecal energy digestibility and a slight reduction in faecal dry matter and nitrogen digestibility. The retention of the minerals sodium, potassium, magnesium, calcium and phosphorus was not influenced to any measurable extent when isomalt was fed.

The effect of starch sources barley, maize and potatoes and their ration portions on the nutrient digestibility and energy utilization in ruminants. 4. Nitrogen metabolism in the rumen

In 9 experimental periods on four adult bulls (LW 550 kg) fitted with re-entrant cannulae in the proximal duodenum isoenergetic rations were used on feeding level 1.7 with ground barley, ground maize or fresh potatoes as starch sources. The net energy parts of these concentrates in the ration amounted to 50, 25 and 10%. 50 to 80% of the ration DM consisted of dried grass and about 10% of sugar beet pulp. The dried grass supplied on an average 87, 79 and 62% of the feed crude protein. The intake of DM was 7.74 +/- 0.42 (mean +/- SD) kg/d. The energetic efficiency of microbial N synthesis in the rumen (g N/kg organic matter true fermented in the rumen, TFOM) was averaged 16.4 with a range of 10.6 to 21.4. The microbial efficiency achieved a maximum when the ratio of nitrogen-free extract to crude fibre in the diet was 1.7 and 2.1 with barley, 1.8 with potatoes and 2.1 and 3.3 with corn as starch source. Changes in the microbial efficiency were positively correlated with the rate of passage of non-microbial organic matter from the rumen (g/d) and with the duodenal flow rate (kg digesta/kg DM intake). The relation to the rate of carbohydrate fermentation in the rumen (in %) and to the amount of TFOM (g/d) was negative. The duodenal flow of microbial N and non-ammonia N (g/d) correlated negatively with the organic matter apparently fermented in the rumen (AFOM) and positively with the non AFOM. The amino acid (AA) profile of the duodenal protein was affected by the starch source. It was concluded that the metabolism of nitrogen in the forestomachs of cattle is affected by the source of starch and the ratio of forage to concentrate. There exists a relationship between both factors. The net synthesis of microbial protein in the rumen is not only the result of substrate fermentation. The passage of non-AFOM from the rumen significantly affects the energetic efficiency of microbial nitrogen synthesis and the duodenal supply of AA.

The effect of flavomycin on digestion in fattening bulls

Three friesian bulls (Genotype 31) were fitted with re-entrant cannulas at the duodenum to investigate the influence of a flavomycin supplement of the digestion in the forestomachs and the other parts of the digestive tract. The supplement of flavomycin increased the total digestibility of the organic matter. The digestibility of starch and sugar was between 97% and 98%. The balance of the nutrients in the digestive tract shows, that by flavomycin supplementation the degradation of organic matter and crude protein in the fore stomach was decreased and the amount of the organic matter and crude protein in the gut was increased. The balance of the amino acids in the gut showed that after flavomycin ca. 30 g more amino acids were found in the gut. The synthesis of bacterial protein in the forestomachs was, after flavomycin application, slightly reduced as was the degradation rate of the feed protein.

Ruminal nitrogen metabolism in calves and sheep. 3. Effect of hay-concentrate ratio in calves

During the milk feeding period (ca. 55th day of life) and 2 weeks after the milk feeding period (ca. 80th day of life) the influence of a hay quota in the ration (on DM basis) of 6, 10, 14 and 18% in the milk feeding period and of 16, 23, 31 and 37% in the period after milk feeding was tested as to ruminal N metabolization with calves supplied with duodenal re-entrant cannulae. The increase of the hay quota in the ration for ruminating calves reduced as a tendency duodenal NAN passage, its bacterial N-quota, post-ruminal NAN digestibility and, due to a worse utilization of available N for bacterial N-synthesis, bacterial N-synthesis rate. The apparent fermentation of organic matter was, as a tendency, increased with the growing hay quota in the ration.

Digestibility and amino acid composition of digesta at the end of the ileum in preruminant calves fed soyabean protein

The ileal digestion of 3 milk substitutes in which skim milk powder was either the only protein source (control diet) or was partially replaced (50%) by a heated soybean flour (SF diet) or an alcohol-treated soyabean protein concentrate (SC diet) was studied in 6 preruminant calves which were fitted with an ileo-caecal re-entrant cannula. The apparent digestibility of total nitrogen and amino acids was lower with the SF and SC diets than with the control diet (0.89, 0.89 and 0.94, respectively, for amino acid nitrogen). Assuming that true digestibility was complete with the control diet, the values were lower with the SF and SC diets, especially for cystine, threonine, valine, isoleucine, leucine and histidine. With the SF and SC diets, digesta contained more aspartic acid and glutamic acid but less threonine, sulfur amino acids, lysine, serine and alanine than with the control diet. The additional undigested fractions obtained with the SF and SC diets compared to the control diet were rich in aspartic and glutamic acids, and poor in arginine, suggesting that partially degraded dietary fractions different from the whole soyabean escaped digestion in the small intestine; these fractions probably originated mainly from glycinin. No significant differences were observed between the 2 soyabean diets.

Einfluss der stärkeherkünfte gerste, mais und kartoffeln und ihrer rationsanteile auf die nährstoffverdaulichkeit und die energieverwertung bei wiederkäuern

The investigations of this paper are part of a complex research project to develop energetic feed evaluation within the Net Energy Fat System. The aim was to obtain new results to estimate the relation between place as well as kind of nutrient digestion and energetic utilization of rations in cattle. The ruminal nutrient digestibility was measured in adult oxen on feeding level 1.7 by means of duodenal reentrant cannula for 9 rations including the starch sources barley, maize and potatoes and with their energy parts of 50, 25 and 10%. The intake of starch ranged from 484 to 2573 g/animal.d and the amounts of ruminal and postruminal digested starch from 444 to 2336 as well as 10 to 284 g/animal.d. For the organic matter, starch, water soluble carbohydrates and N free residual substances high relative parts of ruminal digested from apparent digested nutrients were measured with values between 78 and 88, 83 and 98, 93 and 97 as well as 88 and 100% respectively.

Effects of Raw Pea Flour on Nutrient Digestibility and Immune Responses in the Preruminant Calf

Two milk substitute diets for which the protein was provided either exclusively by skim milk powder (control) or partially (34%) by dehulled raw pea flour were given for 2 and 4 wk, respectively, to five preruminant calves, each fitted with a reentrant ileocecal cannula. Ileal apparent digestibility was lower with the pea diet during wk 1 than with the control diet. Four of the cannulated calves exhibited significant intolerance to the pea diet, resulting in lower digestibility during wk 4. In contrast, fecal digestibility of the pea diet, measured in four additional calves without reentrant cannulas, did not significantly decrease between wk 1 and 4. The AA composition of ileal digesta from the first group of calves did not vary greatly, suggesting that the differences observed in their apparent digestibility of proteins were due mainly to changes in the loss of endogenous proteins. However, pea legumin survived digestion in the small intestine in amounts generally equivalent to 1 to 3% of intake. Most of that undigested fraction was smaller than the native legumin: 40 to 200kDa instead of 360kDa. Also, a 45-kDa fragment was detected in the urine. Increased intestinal permeability could have favored the development of the high systemic anti-pea antibody titers that were observed in all of the calves.

Tracer studies of urea kinetics in growing pigs: I. The effect of intravenous infusion of urea on urea recycling and the site of urea secretion into the gastrointestinal tract

Four gilts (average BW 80 kg) were used in the first experiment to study the effect of i.v. infusion of urea on urea kinetics by means of a radioisotope dilution technique. The pigs were fed twice daily 600 g of a cornstarch-based diet formulated to contain 16% CP by supplementation with isolated soy protein. Infusion of urea, compared with saline, increased (P < .05) plasma urea concentration, urea pool size, urea entry, urea excretion, and urea degradation rates; urea turnover rate and urea space were not affected (P > .05). Expressed as a percentage of the total entry rate, a lower (P < .05) percentage of urea was recycled in pigs infused with urea. The urea infused was almost completely excreted in urine, so there were no differences (P > .05) in N balance. In the second experiment, four gilts (average BW 40 kg), fitted with ileocecal reentrant cannulas, were used to determine whether the upper or the lower digestive tract represents the preferential site of urea secretion in pigs. Two pigs were fed twice daily 600 g of a cornstarch-based diet, formulated to contain 16% CP from soybean meal. The other two pigs were fed the same diet in which 15% cornstarch was replaced by beet pulp. After labeling the body urea pool of one pig on each treatment with [15N]urea, the reentrant cannulas were disconnected to prevent the flow of digesta from the small into the large intestine.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of niacin supplementation on the concentration of niacin in rumen and duodenal digesta and in whole blood of sheep.

1. Niacin concentrations in rumen liquor, duodenal digesta and blood, and daily duodenal flow of niacin were measured in four wethers which were fed an oatstraw grain concentrate diet (with normal niacin content) or an oatstraw maize diet (with low niacin content). The effect of an intraruminal supplementation of 2 mmoles nicotinic acid (NIA) or nicotinamide (NAM) on concentrations of NIA and NAM in gastrointestinal contents and blood and on daily duodenal flow of NIA and NAM was studied. The animals were equipped with rumen fistula and duodenal re-entrant cannulae. 2. NIA concentration in strained rumen liquor was 384 and 264 nmol/ml and daily duodenal flow of niacin was 616 and 528 mumoles/d in animals fed normal or low niacin diet, respectively. Intraruminal administrations of 2 mmoles of NIA or NAM raised NIA concentration in strained rumen liquor for approximately 6 h. About 20% of the administered dose of NIA or NAM passed out of the rumen and resulted in a 41% increase in daily duodenal flow of niacin. The remaining 80% of the administered dose of NIA or NAM disappeared from rumen liquor without being washed out. 3. Supplemented NAM was rapidly hydrolyzed to NIA and ammonia when administered into the rumen. 4. NAM concentration in blood appeared to be unaffected by the dietary content of NIA or by niacin supplementation. 5. The NIA concentration in strained rumen liquor was positively related with niacin content of the diet. Increases in duodenal flow of niacin had no marked effect on concentration of NAM in blood. It appeared that feeding diets with different NIA content affected apparent niacin synthesis in the rumen.

Studies of the digestibility of pigs fed dietary sucrose, fructose or glucose.

Digestion of sucrose, fructose and glucose was studied in pigs with reentrant cannulas in the distal ileum or intact pigs fed diets formulated with sucrose, fructose and glucose as the major energy source and torula yeast. Sucrose and glucose were completely digested in the small intestine (apparent digestibility, 98.3 and 98.3%, respectively but a fraction of the dietary fructose escaped to the large intestine (adjusted value, 11.7%). There was no carbohydrate in rectal contents of the pigs. There was no carbohydrate influence on the pre-caecal or total digestibility of nitrogen.

The nitrogen metabolism in the large intestine of ruminants. 8. Metabolism of intracecally infused 15N-urea with a supplement of pectin in heifers

Three heifers with live weights of 255, 261 and 300 kg were supplied with ileo-caecal re-entrant cannulas, jugular vena catheters and bladder catheters. The ration consisted of 4 kg maize silage and 4 kg wheat straw pellets. In a previous period 50% of the digesta flow was collected over 12 h/d on 5 consecutive days and stored in a deep-freeze. During the main period the re-entrant cannulas were disrupted and the flowing digesta was quantitatively collected. Precollected digesta and pectin were infused into the distal part of cannula hourly for about 30 hours. During the first 24 hours the digesta was also supplemented with 15N-labelled urea. The amount of pectin corresponded to about 10% of digesta dry mater. An analysis of urine, faeces, digesta and blood plasma were carried out. The application of pectin increased the 15N-incorporation in the bacterial protein of faeces from 4.7% (without supplementation in an earlier experiment) to 10.5% of the introduced 15N. The ammonia-fraction of faeces was markedly higher than the bacterial fraction. The 15N-utilization of urea by the microbes of large intestine was lower in the actual trial evident than with supplementation of starch in the anterior experiment. During the pectin administration the amount of urine increased in comparison with earlier experiments and according to the literature to about the 4.5 fold. The amount of passage of 15N at the ileum cannula (recycled 15N) was 3.8% of the 15N intake. It is the same amount as in experiments in which starch was applied.

Replacement of chloride deficit by use of 1.8% NaCl to correct experimentally induced hypochloremic metabolic alkalosis in sheep

SUMMARY Five adult 40- to 50-kg female sheep were surgically fitted with a reentrant cannulae placed in the proximal part of the duodenum just distal to the pylorus. By diversion of abomasal outflow, this model has been shown to produce hypochloremic metabolic alkalosis accompanied by dehydration, hypokalemia, and hyponatremia. Each sheep was subjected to 3 separate, 12-hour iv treatment trials, in each case preceded by a control period of 48 hours, and a diversion period of 36 to 96 hours, during which a hypochloremic (Cl− ≤ 60 ± 2 mEq/L) metabolic alkalosis with hypokalemia and hyponatremia was produced. Treatment 1, consisting of 6 L of isotonic Na gluconate, was designed to replace volume without replenishing the Cl− deficit. Although hydration improved, plasma Cl− decreased further, and the sheep became increasingly weak and depressed. Treatment 2, consisting of 2 L of 1.8% NaCl, was designed to replace the Cl− deficit without replacing total volume. Plasma Na+ and Cl− concentrations returned to normal during the 12 hours of treatment; acid-base balance and plasma K+ concentrations returned to normal within 36 hours of treatment. During treatment 3 (control, no treatment), measured metabolic values changed minimally. We concluded that the iv replacement of Cl− without K+ is effective in the correction of experimentally induced hypochloremic metabolic alkalosis in sheep.

Influence of different cannulation techniques on the pre-caecal digestibility of protein, amino acids and cell wall constituents from diets, containing different protein meals, in pigs

A direct comparison of the ileal digestibility of protein, amino acids and cell wall constituents, measured using the simple cannula (spot sampling) and re-entrant cannula (quantitative sampling) techniques, was carried out with six pigs fitted with each type of cannula. During the experiment, the live weights of the animals ranged from 40 to 90 kg. Six diets were offered, including the following: a commercial ration commonly used in China which is based on maize, rice husk meal and fish meal (B); two diets in which part of Diet B was replaced by 15% oil-tea camellia cake (BTM) or rapeseed meal (BRM); two monodiets of maize with a high (MHL) or low (M) lysine content, plus Diet M with 15% of the maize replaced by peanut meal (MPM). Chromic oxide formed 2 g kg −1 of the diets to permit calculation of digestibility by spot sampling. With the exception of one maize diet and the MPM diet, the spot-sampling method gave higher digestibilily values for dry matter, protein and amino acids than the quantitative sampling method. Conversely, the digestibility values of neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) measured with the simple cannula technique were considerably lower than these measured with the re-entrant technique. This study indicated that the re-entrant cannula technique cannot be replaced by the simple cannula technique in the determination of pre-caecal digestibility in monogastrics, particularly the digestibility of cell wall constituents of compound feeds.

Nachweis einer Mikrobiellen Proteinsynthese im Dünndarm von Schafen mittels einer Intraduodenalen 15N-Harnstoffinfusion

Sheep (3 animals, 50 kg LW) with reentrant cannulas in duodenum and at the end of the ileum received 700 g hay and 800 g alfalfa pellets per animal and day. In a previous 1st period of three days duodenal digesta and in a 2nd period of four days ileal digesta were collected and stored deep frozen. In the main period the digesta flow was interrupted for 28 hours. The duodenal and ileal digesta were collected quantitatively. The previously collected duodenal and ileal digesta portions were introduced hourly. The duodenal digesta was supplemented with 15N-labelled urea for a 24 hour period. 4.5% of the introduced 15N-excess were detected at the end of the ileum in the 24 hour period. 5.6% of the 15N-excess at the end of the ileum were incorporated in bacterial protein. It was measured that the ileal digesta contained 4.62 g N in the TCE precipitable fraction and 24.4% of the TCE precipitable N-fraction was bacterial nitrogen.

Duodenal flow of nitrogen following protozoal inoculation of fauna-free sheep fed a diet supplemented with casein or soybean meal

Fauna-free sheep, equipped with a rumen cannula and a duodenal re-entrant cannula, were fed a corn silage diet supplemented with casein (CA diet) or soybean meal (SBM diet). Eighteen days later the sheep were inoculated via the rumen cannula with a mixed population of ciliate protozoa. Rumen fluid and duodenal digesta were sampled for 4 d before the inoculation and for 13 d following the inoculation. A stable protozoal population was established within 8 d. Protozoa increased (P &lt; 0.05) the digestion of organic matter in the stomach of sheep fed both the CA and the SBM diet, but the effects of supplemental protein and protein × protozoa interaction were not significant (P &gt; 0.05). The stomach digestion of acid detergent fibre was not affected (P &gt; 0.05) by protozoa or by the source of supplementary protein, but the protein × protozoa interaction was significant (P &lt; 0.05). The disappearance of nitrogen from the stomach was lower (P &lt; 0.01) for the SBM diet than for the CA diet and was increased (P &lt; 0.05) for both diets in the presence of protozoa, but the effect of protein × protozoa interaction was not significant (P &gt; 0.05). The ruminal presence of protozoa decreased the flow from the stomach of individual amino acids (from P &lt; 0.05 to P &lt; 0.001) and of nonammonia nitrogen (P &lt; 0.05). However, the decreases were greater (from P &lt; 0.05 to P &lt; 0.001) for the CA diet than for the SBM diet, but the effects of protein × protozoa interaction were not significant (P &gt; 0.05). The ruminal presence of protozoa increased (P &lt; 0.05) the flow from the stomach of ammonia-N for SBM diet but not for CA diet. The effects of protein and of protein × protozoa interaction were not significant (P &gt; 0.05). It was concluded that although ruminal protozoa do not metabolize casein, their effect of decreasing amino acid flow from the stomach can be greater for diets containing casein (soluble protein) as protein supplement than for those containing soybean meal (insoluble protein). Key words: Duodenal flow, nitrogen, protozoa, casein, soybean meal, sheep

Postileal nutrient digestibility in cattle

Four heifers of an average live weight of 301 kg supplied with ileocaecal re-entrant cannulae received rations consisting of 4 kg hay (variants A und B), 1 kg coarse wheat meal, 0.4 kg molasses, 100 g urea and 30 g mixed minerals per animal and day. After a 14-day preliminary feeding period the ileum digesta was quantitatively collected at the re-entrant cannula over 24 h. 10% of the digesta were used for analysis, the remainder was heated to 37 degrees C and returned. Under consideration of the digesta passage through the colon the 24-hour collection of faeces was started after a 6-hour delay after the first replacement of digesta. Losses of nutrients were calculated from the values analysed from digesta and faeces. No differences could be ascertained between the two hay variants. On an average of the two rations the nutrient losses of the scaffold substances-equivalent to the digestibility in the colon-showed the following values: crude fibre = 10.6%, NDF = 10.4%, ADF = 11.9% and hemicellulose = 7.4%. The losses of the other nutrients, corresponding to their apparent digestibility, had the following values: crude protein = 12.1%, crude fat = 10.7%, N-free extracts = 18.9%, ash = 31.2%, dry matter = 17.5%. The water balance showed that 8.2 l water of the 23.4 l supplied with the ileum digesta were excreted in faeces.

Urinary excretion of allantoin and allantoin precursors by sheep after different rates of purine infusion into the duodenum

SUMMARYTwo experiments were carried out to determine endogenous losses and the response of urinary purine derivatives to increased duodenal inputs of purine bases. Four ewes each fitted with a re-entrant cannula at the proximal duodenum, and conventionally fed, were subjected to full replacement of duodenal digesta followed by the administration of a solution either free of purines (Expt 1) or enriched with increasing amounts of purines, to supply 0·48–21·27 mmol/animal per day (Expt 2). Basal daily urinary excretions of allantoin, uric acid, hypoxanthine and xanthine were 11·5 ± 0·94, 9·9 ± 0·67, 6·9 ± 0·46 and 1·2 ±0·16 mg/kg W0·75. Allantoin was the only purine derivative which increased in response to incremental inputs of duodenal purines. The relationship between allantoin excretion and infused purines showed a urinary recovery of 0·8 for purines infused at &gt; 220 μmol/kg W0·76. Lower rates of infusion did not alter allantoin excretion. The results show urinary allantoin to be a useful index to estimate duodenal input of purines when animals are fed close to or above their energy maintenance requirements.