Digesta Flow Research Articles

The Use of a “Tt” Shaped Cannula for Collection of Duodenal Digesta in Sheep

Six sheep were equipped with both a rumen fistula and a duodenal cannula. The duodenal cannula was made of two ordinary T shape cannulas which were vulcanized into a double T cannula. Both the rumen and the duodenal cannulas were made of soft rubber. In two experiments six different diets were fed. In the first experiment the diets consisted mainly of ammonia-treated straw (NH3-straw) plus barley or sodium hydroxide-treated straw (NaOH-straw) plus concentrate containing different N-supplements. In the second experiment, the treated straw (either NH3-straw or NaOH-straw) was fed alone. The animals in the two experiments were fed at maintenance level. Duodenal digesta were collected for periods of 12 h by inflating a balloon in the distal flange of the cannula, using pieces of foam rubber. The volume of fluid leaving the rumen was measured using the marker Gr-EDTA. The effect of digesta removal on blood constituents was studied. Three to four observations on each ration were made. Digesta flow and dry matter entering the duodenum were higher with NH3-straw than NaOH-straw fed either alone or with concentrate. However, there was a considerable variation of which a large part was of individual nature. The volume of fluid reaching the duodenum was always lower than the volume leaving the rumen, indicating a net absorption of water in the omasum and abomasum. This was estimated to be from 10.1 to 11.6 1/24 h in Experiment 1 and from 0.3 to 1.4 1/24 h in Experiment 2 (51–59 and 5–31 % of the ruminai outflow, respectively). A significant increase in plasma K and Mg and decrease in Pi and a-amino N concentration were observed due to 12 h collection of duodenal digesta. However, plasma Na, Ca, glucose and urea nitrogen concentrations remained at their pre-collection levels. Post-mortem examination of duodenum in sheep slaughtered after six and 10 months revealed a normal gut with no sign of dilatation in the immediate vicinity of the cannula.

Utilization of low quality roughages: effects of urea and protein supplements of differing solubility on digesta flows, intake and growth rate of cattle eating oaten chaff.

1. Expt 1. Five 150 kg steers with ruminal, abomasal and ileal cannulas were given 3000 g oaten chaff daily plus pelleted supplement with no added nitrogen (diet A) of 50 g N/d as urea (diet B), casein (diet C), casein and formaldehyde-treated casein (HCHO-casein) (50:50 w/w; diet D) and HCHO-casein (diet E), in a 5 x 5 Latin square design. The basal diet and supplement were fed in eight equal increments at intervals of 3 h. Proportions of dry matter and organic matter digested in the stomach and whole tract were greater for diets B, C, D and E than for diet A. Total volatile fatty acid levels in the rumen and the proportion of acetic acid, were lower, and the proportion of propionic acid higher on diet A than on the other diets. Rumen ammonia levels were lower on diets A, D and E than on diets B and C. N flows at the abomasum, ileum and rectum were lower on diet A than on the other diets; abomasal flows and apparent intestinal absorptions of amino acids were higher on diets D and E than on diets A, B and C. Efficiencies of bacterial protein synthesis were 15, 15, 14, 13 and 12 g bacterial N/kg OM truly digested in the stomach on diets A, B, C, D and E respectively. 2. Expt 2. Forty 300 kg steers were fed oaten chaff ad lib. plus twice the amount of the same pelleted supplements as in Expt 1. Intake of oaten chaff was 23% higher with N supplements (diets B, C, D and E) than without (diet A). Live-weight gains were 356, 798, 843, 842 and 805 g/d on diets A, B, C, D and E respectively. 3. It was concluded that efficiency of bacterial protein synthesis was not limited by the supply of peptides and amino acids in the rumen, and that increases in amino acid availability in the intestines from feeding HCHO-casein did not increase food intake or live-weight gain.

Concurrent studies of the flow of digesta in the duodenum and of exocrine pancreatic secretion of calves. 7. Influence of milk substitutes on abomasal lipolysis and biliary secretion.

1. The abomasal hydrolysis of lipids and the flow of endogenous (biliary) lipids was studied in two Friesian calves given four milk-substitute diets, by sampling the duodenal digesta. The diets were: reconstituted, mildly preheated, spray-dried skim-milk powder with (SKF) or without (SK) margarine fat or with 500 g/kg skim-milk powder in diet SKF replaced by soy-beran flour (ASKF) or fish-protein concentrate (BSKF) together with dried whey. The diets were given ad lib. twice daily from 13 to 37 d of age, each diet being given for six consecutive days. Collections of duodenal digesta from the re-entrant cannula situated caudal to the bile duct were made for 12 h after feeding the 6th and 12th meals for each diet. Samples from one collection only were subjected to detailed analysis of the lipid classes. 2. The inclusion of non-milk protein (ASKF and BSKF) not only increased the rate of passage of lipid through the abomasum but also the proportion of the lipid present as triglyceride particularly, in the first 2 h after feeding. 3. In a 12 h period, 2.3-6.3 g 'polar' lipids (mainly biliary phospholipids) were estimated to have been secreted. The rate of flow was high during the first hour after feeding and constant thereafter. The quantity of 'polar' lipid was not related to the type of milk fed or the duodenal flow of lipid. 4. When diet SK was fed, the small amounts of lipid present were extensively hydrolysed so that free fatty acids represented 700 g/kg lipid of dietary origin passing through the duodenum. When margarine fat was included in the diets (SKF, ASKF and BSKF), the free fatty acids represented only 210 g/kg lipid of dietary origin. 5. The quantities of lipid and nitrogen passing through the duodenum were poorly related to the quantities ingested at the beginning of the 12 h experimental period but were closely related to each other.

Apparatus for Measuring and Subsampling Digesta in Ruminants Equipped with Reentrant Intestinal Cannulas2

A completely automated device for quantitatively measuring and sampling digesta entering the proximal duodenum of cattle is described. The system operates according to volume of flow from intestinal reentry cannulas. Size of subsample, frequency of sampling and rate of digesta return may be varied according to experimental objectives. The apparatus has the following features: (1) digesta temperature control, (2) a rotary sample collector to obtain individual subsamples, and (3) an event recorder to indicate flow cycle time parameters. The system described was constructed for cattle and may be used with animals standing or lying in the special holding crate. The apparatus has logged in excess of 1,900 hr of continuous collection (53 periods of 36 hr each) with only minor malfunction. Repetitive sampling of pooled digesta has produced coefficients of variation for volume, dry matter flow and percentage dry matter in digesta samples of 2.68, 2.81 and 1.81%, respectively. On the basis of incomplete recovery (range 71 to 97%) of chromic oxide from animals during collection periods (24 hr fed vs 24 hr recovery at duodenum), it is suspected that some inhibition to normal flow through the cannula occurs during sampling. Experiments have been conducted in which several parameters of interest were measured and total collection of digesta was compared via spot sampling (500 ml digesta at 6-hr intervals for 48 hr). When corrected to 100% chromic oxide recovery, differences between techniques for estimates of total digesta flow, organic matter and nitrogen entering the duodenum were small and not significant.

Effect of Sampling Intervals and Digesta Markers on Abomasal Flow Determinations

Four sampling schedules and three digesta markers were investigated with abomasally-cannulated steers. Nonammonia nitrogen flow through the abomasum was used as the criterion for comparison. A single diet, consisting of ground corn cobs and cane molasses and supplemented with soybean meal to 11.5% crude protein, was used. Each steer was fed hourly to maintain a constant digesta flow. Digesta markers used were: polyethylene glycol (PEG) and chromic oxide (Cr2O3), as external markers for the liquid fraction and the particulate fraction, respectively; and indigestible neutral detergent fiber (INDF) and indigestible acid detergent fiber (IADF), as internal markers for the particulate fraction. Treatments were sampling intervals of 24 hr, 48 hr, 48 hr (sampled twice) and 72 hours. Sampling interval did not alter digesta flow through the abomasum. Extending sampling intervals beyond 24 hr or taking more than one sample per day did not appear advantageous. IADF and Cr2O3 appear to be suitable markers for the particulate fraction. However, IADF is an integral part of the particulate fraction and meets the criteria of an ideal marker.

Rumen bacterial protein synthesis and the proportion of dietary protein escaping degradation in the rumen of sheep.

1. The effect of supplementing barley diets with urea (U), extracted, decorticated groundnut meal (GNM) or Peruvian fish meal (PFM) on rumen bacterial protein synthesis and the proportion of undegraded food protein passing to the duodenum of sheep has been examined. 2. Three wethers were given isonitrogenous, isoenergetic diets containing (g/kg dry matter (DM)): U 20, GNM 106 or PFM 78, the crude protein (nitrogen x 6.25) contents being 139, 145 and 148 respectively. The sheep were fed hourly, the mean daily intake of DM being 0.634 kg. 3. Rumen bacterial protein synthesis was determined using 35S and diaminopimelic acid (DAPA) as bacterial markers and polyethylene glycol (PEG) and chromic oxide as markers of digesta flow. Rumen volatile fatty acid (VFA) production rate was determined by a continuous infusion of [1-14C]acetate. 4. 35S and DAPA gave similar estimates of the proportion of bacterial N in the trichloroacetic acid-precipitable nitrogen of the rumen digesta, the mean value being 0.86. The VFA production rate did not vary significantly between diets, the mean being 5.8 mol/24 h. The flow of bacterial N from the rumen was calculated from the PEG and CR2O3 estimates of flow and the 35S and DAPA estimates of the proportion of bacterial N in the rumen. 35S and DAPA gave similar values (mean 12.5 g/24 h) and Cr2O3 gave a slightly lower value (11.5 g/24 h) than PEG (13.5 g/24 h). Dietary effects, averaged over the four methods, were not significant; the values were 13.0, 13.4 and 11.0 g/24 h for the U, GNM and PFM diets respectively. 5. Duodenal samples were taken from two 12 h continuous collections from re-entrant cannulas and the DM flow adjusted to total recovery of Cr2O3. The mean recovery Cr2O3 at the duodenum was 0.798. The rates of flow of DM were 0.296, 0.311 and 0.334 kg/24 h and of non-ammonia-N (NAN) 13.5, 15.2 and 15.4 g/24 h on the U, GNM and PFM diets respectively. 6. The concentrations of the essential amino acids in duodenal digesta were generally higher with the PFM diet than with either of the other two diets. The flow of most amino acids through the duodenum was generally higher on the PFM and GNM diets than on the U diet. 7. The energetic efficiency of bacterial protein synthesis was calculated to be 2.1 g bacterial N/mol VFA or 28 g bacterial N/kg organic matter fermented in the rumen. 8. From the estimates of bacterial N flow the rumen and NAN flow through the duodenum it was calculated that 0.22 and 0.69 of the supplemental N from GNM and PFM respectively passed through the rumen undegraded.

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.

In vivo measurement of rumen microbial growth using 35S

SummaryA method for the measurement of the net rate of synthesis of rumen microbes, entailing separate infusions of 35S-sulphate into the blood and rumen, is described and compared with estimates derived using digesta flow markers. Measurements were made on seven occasions with sheep and on eight occasions with cattle given chopped hay or pelleted hay diets at intervals of 60 or 90 min. Additional measurements were made on two sheep and two cattle given lucerne hay at intervals of 6 or 12 h. Estimates of microbial synthesis using the proposed method for animals fed at intervals of 60 or 90 min were 0·95–1·23 (mean 1·05) that derived using flow markers. For animals fed at intervals of 6 or 12 h the ratio was more variable, 0·91–1·35 (mean 1·17). The agreement between methods tended to be poor in animals with a low rate of irreversible loss of serum sulphate. The proposed method can be accomplished with a low analytical load, and appears to have potential for application in animals fitted with rumen fistulae only, and fed at infrequent intervals.

The utilization of spear grass (Heteropogon contortus). IV. The nature and flow of digesta in cattle fed on spear grass alone and with protein or nitrogen or sulfur

Digestion studies were carried out with steers fed on low quality spear grass (Heteropogon contortus) alone and supplemented with either urea and sulfur or cottonseed meal. Urea and sulfur were administered by continuous infusion and cottonseed meal by direct addition to the rumen once daily. Supplementation with either non-protein nitrogen or true protein resulted in a significant increase in digestible organic matter intake without any apparent change in the apparent digestibility of the diet. Digestible organic matter intakes were 1.48, 1.88 and 2.28 kg day for spear grass, spear grass plus urea and sulfur and spear grass plus cottonseed meal respectively. On all diets there was a net gain of nitrogen in the stomach, highlighting the role of recycled nitrogen in the digestion of low quality feedstuffs. Thirty-five g of non-amonia nitrogen per day (2.7 g/100 g organic matter digested in the stomach) reached the intestine when the diet was spear grass alone, 46 g (3.0 g/100 g dry organic matter) when the supplement was urea and 72 g (3.8 g/100 g) when the supplement was cottonseed meal. The result demonstrates the limitations of supplements of urea in improving the nitrogen status of animals fed on a basal diet of low quality (low energy) roughage.

自然哺乳子牛の十二脂腸を通過する消化管内容物の流れについて

自然哺乳子牛の十二脂腸を通過する消化管内容物の流れについて

Gastrointestinal allergy to soyabean protein in preruminant calves. Antibody production and digestive disturbances in calves fed heated soyabean flour

Preruminant calves were fed heated soyabean flour as a constituent of a milk based diet. Within two weeks IgG and IgE antibodies specific for soyabean proteins appeared in their serum. To measure the rate of flow of digesta through the small intestine, other calves were cannulated in the abomasum and distal ileum. They were given single experimental feeds containing heated soyabean flour as the sole source of protein. The production of similar antibodies in these animals coincided with an increase in the rate of flow of digesta produced from an experimental feed. These results suggest the development of a gastrointestinal allergy to soyabean proteins.

Corn Particle Size and Site and Extent of Digestion by Steers

The site and extent of starch digestion by steers as influenced by corn particle size was studied in a 4 × 4 Latin square design. Steers (272 kg) fitted with permanent rumen cannulae were fed approximately 3.5 kg dry matter in eight portions daily (3-hr intervals). Site of digestion was estimated by withdrawing rumen samples and assuming such samples would be equivalent to abomasal samples if a constant flow of digesta was maintained by frequent feeding. Ruminal digestion of dry matter (DMD), organic matter (OMD) and starch was estimated by the ratio of permanganate lignin in feed to lignin in rumen digesta. Corn was fed whole or following grinding through 3.18, 4.76 or 7.94mm screens and comprised 72% of the diets. Geometric mean diameters (micrometers) of the four grains were as follows: whole (5978 $#x03BC;m), 3.18mm (509 μm), 4.76mm (588 μm) and 7.94mm (832 μm). In view of high and variable lignin digestibilities, ruminal digestibility estimates indicate trends rather than absolute values. Ruminal DMD was lower (P<.05) for whole corn (44.9%) than for that ground through 3.18mm (62.3%), 4.76mm (63.6%) and 7.94mm (60.8%) screens. This permitted intestinal DMD to be greater (P<.05) for whole corn and suggests increased quantitative importance of intestinal digestion for whole corn. Whole corn also had a lower (P<.05) ruminal starch digestibility (70.8%) than ground corn treatments (avg 91.7%). Moreover, total tract starch digestion was lower for whole 88.2%) than for 3.18mm (94.5%), 4.76mm (93.7%) and 7.94mm (93.5%) treatments. Intestinal starch digestion was generally low, particularly on ground corn treatments. Alteration of the whole kernel beyond mastication appears necessary to maximize total starch digestion. Rumen pH and liquid outflow rate were not greatly influenced by corn particle size, but tended to increase with particle size. Fecal pH was not related to starch content of feces and ruminal liquid dilution rate was not related to molar percentage acetate, propionate or butyrate.

Digesta flow and mineral absorption in lambs before and after weaning

SummaryFour young lambs fitted with cannulas at the pylorus and at the ileo-caecal junction were used to study the effects of weaning on digesta flow and mineral absorption. Prior to weaning when milk alone was fed the small intestine was the major site for dry matter disappearance and for the absorption of Ca, P, Na and K. Both the small and the large intestine were, however, important sites for Mg absorption at this time.After weaning, when the lambs were fed a concentrate diet, at least two-thirds of the digested dry matter disappeared within the reticulo-rumen. The small intestine, however, still remained the major site for the absorption of Ca, P, Na and K. Most Mg absorption, in contrast, now occurred anterior to the pylorus and it would appear that the move from hindgut to foregut as a site for Mg absorption was directly associated with the introduction of dry feed and the development of fermentative digestion within the reticulo-rumen.Both before and after weaning the faeces was the major route for the excretion of Ca surplus to requirement and the faeces also became increasingly important as a pathway for P and Mg excretion once dry feed was given. The urine, in contrast, was consistently the major pathway for the excretion of Na and K.

Artificial rearing of pigs

1. Half (diet M) or total replacement (diet N) of dried skim-milk by fish-protein concentrate and dried whey was compared with a diet containing dried skim-milk (710 g/kg) as the only source of protein (diet A). All three diets were prepared as spray-dried powders, and contained 20 g starch and 270 g soya-bean oil/kg. The diets were calculated to be isonitrogenous, but upon analysis had crude protein (nitrogen × 6.25) contents (g/kg) of 230, 270 and 291 in diets A, M and N respectively.2. The diets were reconstituted as liquids containing 200 g dry matter (DM)/l and given to pigs weaned at 2 d of age during a 26 d experiment. The diets were fed at hourly intervals to a scale based on live weight. Protein digestion was studied in pigs, 6 d of age, and killed 1 h after a feed.3. Live-weight gain was slightly improved when half the dried skim-milk was replaced, but the feed: gain ratio (g DM consumed/g live weight gain) was unaltered. Total replacement of dried skim-milk, markedly reduced performance and increased the incidence of scouring and mortality.4. Increasing the proportion of fish protein reduced the apparant digestibility (AD) and the retention of N (g/d per kg live weight). N retention, but not AD, decreased with age.5. Total replacement of dried skim-milk decreased the amount of digesta in the stomach, its pH value, and the proportion of DM and total N in the digesta, but non-protein N as a proportion of total N was increased.6. The total pepsin activity in the stomach digesta was decreased by the substitution with fish protein, but there was no change in the activity of the stomach tissue. Trypsin and chymotrypsin activities in the pancreas were not affected by the source of dietary protein, but in the digesta of the small intestine the activity of these two enzymes was markedly reduced when the diet contained fish protein.7. Total replacement of dried skim-milk with fish-protein concentrate and dried whey may increase the rate of flow of digesta through the small intestine, which together with the reductions in the apparent digestibility of N and amounts of trypsin and chymotrypsin in the digesta could reduce the efficiency of protein digestion and adversely affect performance.

Herbage digestion in the stomach and intestines of weaner lambs at different stages of their maturity

Various parameters relating to digestion of a clover diet in the stomach and intestines were measured by marker techniques in the same weaner lambs at 15, 24 and 40 weeks of age when body weights averaged 18, 29 and 44 kg respectively. Significant small changes were observed with increasing age and body size in the values of several of the parameters measured. Thus at 40 weeks relative to 15 weeks values were higher for (i) crude protein digested in the intestines per unit feed intake (+ 10%), (ii) sodium content of rumen liquor and sodium flow from the rumen per unit feed intake (+ 9%, + 14%), (iii) potassium and chloride contents of abomasal liquor (+ 9%, + 7%) and (iv) pH of abomasal digesta (+ 0.3 pH unit). Values were lower for (v) digestibility of organic matter and cell wall constituents in the whole alimentary tract (c. – 1.8%), (vi) ammonia content of rumen liquor and ammonia flow from the rumen and abomasum per unit feed intake (– 15% to – 20%) and (vii) potassium content of rumen liquor (– 9%). No changes attributable to age or body size were observed with several paramefers, including (i) rate of production of volatile fatty acids in the rumen per unit feed intake, (ii) rate of absorption of volatile fatty acids from the rumen, (iii) rate of flow of digesta through the stomach per unit feed intake, and (iv) mean residence time of water-soluble marker in the rumen. The results indicate that care needs to be exercised in applying digestion data obtained with adult sheep to the nutrition of the growing weaner lamb.

Studies on digestion and absorption in the intestines of growing pigs

1. Digesta were collected from seventeen pigs initially of 30 kg live weight fitted with single re-entrant cannulas in either the duodenum, jejunum or ileum. A further twenty-four pigs were used in a conventional digestibility trial. 2. The pigs received three types of diet containing: barley, fine wheat offal, white fish meal, minerals and vitamins (diet BWF); starch, sucrose, maize, oil, cellulose, minerals and vitamins and either groundnut (diet SSG) or casein (diet SSC). 3. Amino acids were measured in samples representative of the digesta flow in 24 h periods and in the faeces collected in 5 d periods. 4. For each diet the total flow in 24 h periods in the duodenum for aspartic acid, threonine, serine and glycine exceeded or equalled intake, while the amounts of the other amino acids were usually rather less than intake. 5. For each diet in the jejunum, the amounts of glycine and cystine exceeded intake in 24 h periods, while methionine, arginine and tyrosine were the most rapidly absorbed amino acids anterior to the cannula site. On average 0.22, 0.25 and 0.31 of the dietary amino acids were absorbed anterior to the cannula site for diets BWF, SSG and SSC, respectively. 6. For each diet in the ileum, the least apparently absorbed dietary amino acids were glycine and cystine. On average 0.81, 0.83 and 0.95 of the dietary amino acids were absorbed anterior to the cannula site for diets BWF, SSG and SSC, respectively. 7. There was net disappearance of most amino acids in the large intestine, but some net accumulation occurred in this region. 8. The results are discussed in relation to the amino acid composition of endogenous secretions (particularly glycine in bile), protease and peptidase specificity, free amino acid absorption and the role of the microflora in the large intestine.

Concurrent studies of the flow of digesta in the duodenum and of exocrine pancreatic secretion in calves. 6. The effect of feeding warm or cold milk by bucket or teat.

1. The effects of bucket- v. teat-feeding and warm- v. cold-milk feeding on the flow of duodenal digesta and the concurrent pancreatic secretion were studied in two experiments in preruminant Ayrshire calves (28–43 d of age), fitted with duodenal re-entrant and pancreatic sac cannulas.2. As measured by the time interval taken for total recovery of the polyethylene glycol fed in the milk, the whey fluids had a more rapid passage through the abomasum when the calves were given warm milk by teat rather than by bucket (Expts 1 and 2). The duodenal digesta contained less sodium ions and more ‘Cl-Na+’ when the calves were fed by teat even though the volumes of milk drunk and duodenal flow were similar. It was concluded that more abomasal acid was secreted when calves were fed by teat.3. When the calves were fed by teat rather than by bucket, the protein-nitrogen : N (PN : N) in the duodenal digesta was lower, especially during the first 6 h after feeding and there was a tendency for more pancreatic proteases to be secreted.4. In Expt 1, when the calves were given warm milk the total flow of N and lipid in the duodenal digesta was 22 and 19% greater than that ingested. This was considered to be due to the coagulum from the penultimate meal plus the experimental meal passing more readily through the duodenum when sampling and to endogenous secretion of N and lipid.5. When four Ayrshire calves were bucket-fed cold, rather than warm milk there was a reduced secretion of abomasal and pancreatic fluids and abomasal acid. There were no differences in the time interval required for the whey fluids to leave the abomasum or the PN : N value.6. There was a positive correlation between the total duodenal flow of non-whey fluids and the pancreatic secretion regardless of the method of feeding.7. The completeness of digestion and susceptibility of calves to diarrhoea when fed by teat and bucket is discussed.

Measurement of flow and sampling of digesta in the preruminant calf.

1. Methods of measuring and sampling the flow of digesta passing through intestinal cannulas in preruminant calves were studied and compared. 2. The effect of collecting digesta from a duodenal cannula on abomasal emptying in a calf given whole milk was determined. When digesta were collected and returned to the duodenum manually in large amounts (about 200 g) the outflow of abomasal contents was intermittent. When digesta were returned to the animal either manually or automatically in amounts of less than about 50 g abomasal emptying was smooth. 3. An automatic apparatus for measuring and sampling the flow of digesta continuously was developed. The device allowed effluent to be returned smoothly to an ingoing cannula at the same rate that digesta left the outgoing cannula. After a feed of whole milk abomasal contents were observed to enter the duodenum in an orderly series of gushes. Each gush consisted of about 5--30 g of digesta. 4. The apparatus was rearranged to measure the effects of composition of duodenal digesta on abomasal emptying. Replacement of duodenal digesta with a suspension containing heated soyabean flour slowed the abomasal outflow of a feed containing casein. 5. Automatic apparatus was used to collect digesta arriving at the distal ileum. Withholding effluent from the large intestine did not affect the movement of digesta from the ileum.

The digestion of dry-matter, organic matter and nitrogen in calves fed diets containing broiler-house litter

SummaryFour diets were fed to two Friesian bull calves fitted with re-entrant duodenal cannulae. The diets contained no poultry litter (diet 0); 30% poultry litter (diet 30 D); 50% poultry litter (diet 50 D) or 30% poultry litter which had been ensiled at 45% moisture content for 3 weeks (diet 30 W). The total flow of digesta from the abomasum was measured over four 24 h periods for each diet.The flow of dry matter and organic matter to the duodenum was similar on all four diets but the percentage of apparent digestion occurring in the stomach was higher when the diets containing poultry litter were fed.Less nitrogen was digested in the hind gut on diet 30 W than the other three diets. Greater amounts of the nitrogen ingested and also of the nitrogen flowing to the duodenum were apparently digested in the hind gut on the diet containing no poultry litter. Microbial protein synthesized/100 g organic matter apparently digested in the stomachs was lowest when the calves were fed the 30 W diet.The results obtained in these experiments were then used to evaluate the results of growth trials previously reported.

A comparison of two non-radioactive digesta marker systems for the measurement of nutrient flow at the proximal duodenum of calves

SUMMARYThe use of non-radioactive ruthenium phenanthroline (Ru-P) and chromium EDTA (Cr-EDTA) as dual phase markers of digesta flow was examined and compared with chromium sesquioxide (Cr2O3) in conjunction with spot samples of digesta collected from T-shaped cannulae situated in the proximal duodenum of weaned calves.In vitro estimates of organic matter digestibility indicated that on a cubed barley diet, Ru-P exhibited toxic effects at concentrations on 2·2 × 10–5 M and above. No such effects were noted with Cr-EDTA. Subsequently satisfactory infusion rates of 12 mg Ru and 280 mg Cr/kg dry-matter intake were established.Daily flows of organic matter, starch, nitrogen, fibre, sodium and potassium at the proximal duodenum were calculated by the dual phase marker system and by Cr2O3, and regression equations relating these two for each dietary component were calculated. Examination of the intercepts revealed that they all differed significantly from zero (P &lt; 0·05) whilst all the regression coefficients were significantly different from unity (P &lt; 0·05), thus indicating that Cr2O3 underestimated nutrient flows at low flow rates and overestimated them at high flow rates relative to the corresponding estimates based on Ru-P plus Cr-EDTA.