Effects of zinc, copper, and manganese supplementation of high-concentrate ration on gastrointestinal absorption of copper and manganese in Holstein calves

Sixteen Holstein bull calves were fed a high-concentrate ratio supplemented with zinc, copper, and manganese, alone or in combination, for 10 wk. After 6 days of preliminary feeding of chromic oxide, fecal grab-samples were collected for 6 days. Calves were slaughtered, and samples of the contents of the reticulo-rumen, omasum, abomasum, small intestine, cecum, and large intestine were analyzed for chromic oxide, copper, and manganese. Absorption along the gastrointestinal tract, measured by comparison of one segment with the previous segment, indicated net secretion of copper in the abomasum but net absorption from the rest of the tract. The exception was that net secretion into the reticulo-rumen was associated with low dietary copper. Net secretion of manganese was mainly in the small intestine and cecum in all treatments. A higher proportion of copper apparently was absorbed when this mineral was supplemented in the ration. However, absorption of manganese was decreased slightly when manganese was supplemented in the ration. Reabsorption of manganese in the large intestine was probably greater than that of copper.     

Purification of six neurotoxins from the venom of Dendroaspis viridis. Primary structure of two long toxins

1. In the conscious calf it is possible to use duodenal re-entrant cannulae to measure the output of a gastric test meal directly from the proximal cannula placed near the pylorus. At the same time the duodenum can be isolated from the stomach and maintained under constant stimulus by a continual infusion at regulated pressure, volume and temperature into the distal cannula. 2. Under these experimental conditions the pattern of gastric emptying is exponential in form. Thus direct recording of gastric emptying validates indirect methods, such as the serial test meal, where volume markers are used. It appears likely that the exponential pattern of gastric emptying is common to man, dog, cat and calf. 3. When the isolated duodenum was infused with water, the exponential pattern of gastric emptying was maintained even when the volume of meal instilled was increased substantially from 1 to 41. 4. Distension of the stomach by larger test meals did not affect the relative rate of emptying so that the half-time of emptying of all meals was about the same. 5. When the isolated duodenum was infused with 0-06 M-HCl gastric emptying of the smaller meals was almost completely inhibited. The inhibition of gastric evacuation was accompanied by inhibition of the gastric e.m.g. 6. Infusion of the duodenum with acid also produced marked, but not complete, inhibition of emptying the larger test meals but the distension produced by the larger meals appeared to partially overcome the inhibitory effect of the acid duodenal infusate so that a small efflux occurred from the stomach. This small efflux was usually associated with some slight degree of gastric e.m.g. activity. 7. We are still investigating the mechanisms whereby the duodenum affects gastric emptying, but it is clearly demonstrable from our present results that the inhibitory effects of acid duodenal infusate are sufficiently powerful to overcome the forces, both physical and reflex, which normally aid gastric evacuation.     

Effects of varying levels of duodenal or midjejunal glucose and 2-deoxyglucose infusion on small intestinal disappearance and net portal glucose flux in steers

Six crossbred steers (261 +/- 18 kg BW) fitted with hepatic portal, mesenteric venous and arterial catheters, and duodenal, midjejunal, and ileal cannulas were used in a replicated 3 x 3 Latin square design to determine the effect of varying levels and site of glucose plus 2-deoxyglucose (2DG) infusion on net portal-drained visceral flux. Steers were fed chopped alfalfa in six equal portions daily at 1.5% of BW. Glucose (0, 9, or 18 g/h) and 2DG (0, 1, or 2 g/h) were infused continuously through the duodenal or midjejunal cannula (two infusion sites) at total glucose plus 2DG infusion rates of 0, 10, or 20 g/h. Arterial and portal blood samples were taken simultaneously at 20-min intervals from 5 to 9 h of infusion. Portal blood flow was determined by continuous infusion of p-aminohippurate and net flux was calculated as venous-arterial concentration (PA) difference times blood flow. Arterial concentration of glucose was not affected (P > .10) by glucose plus 2DG infusion, whereas arterial concentration of 2DG was greater (P < .05) when glucose plus 2DG was infused into the duodenum and increased (linear, P < .10) as amount of glucose plus 2DG infused into both the duodenum and midjejunum increased. Net portal flux and PA difference of glucose and 2DG were greater (P < .05) when glucose plus 2DG was infused into the duodenum. Although 2DG was infused at 10% of the total glucose plus 2DG infusion, it accounted for only 1.7 and .7% of the glucose plus 2DG appearing in portal blood when glucose plus 2DG was infused at 10 and 20 g/h, respectively. We conclude that glucose is more readily absorbed across the proximal-half than the distal-half of the small intestine, and that passive diffusion is a minor route of glucose absorption.     

Effect of enteric nonnutrient infusions on motor patterns in neurally intact and neurally isolated canine jejunum

Previous work in our laboratory has shown that nonnutrient mechanical factors initiate changes in motility patterns in local and remote regions of the small intestine. Our aims were to determine how isolated duodenal and jejunoileal nonnutrient infusions alter interdigestive motor patterns locally and distantly and whether these effects are neurally mediated. Ten dogs were prepared with duodenal and proximal jejunal infusion and manometry catheters and a proximal jejunal diverting cannula. Five of these dogs served as neurally intact controls (Group 1) and five also underwent in situ neural isolation of the entire jejunoileum (Group 2: extrinsic denervation; disruption of enteric myoneural continuity with duodenum). After recovery, nonnutrient infusions at 0-15 ml/min for 5 hr into proximal duodenum or jejunum did not consistently affect cycling of the migrating motor complex (MMC). The period and duration of individual phases of the MMC and time to first phase III after the start of infusion were similar in both groups. In Group 2, duodenal characteristics (period and duration of phase II, time to first phase III) increased slightly with increasing rates of jejunal but not duodenal infusion. Motility indices, although greater in Group 2, were not altered by enteric infusions. Differing rates of nonnutrient enteric flow limited to duodenum or jejunoileum did not affect markedly local or distant motor patterns. Alterations in interdigestive motility patterns by postprandial nonnutrient intraluminal content are not mediated directly by intraluminal flow.     

Effects of supplemental protein source on intraruminal fermentation, protein degradation, and amino acid absorption

Cannulated steers were used to determine the effects of supplemental soybean meal, heated soybean meal, fish meal, and a combination of fish meal, heated soybean meal, and corn gluten meal on intraruminal protein degradation and absorption of AA from the small intestine. Organic matter digestion in the reticulo-rumen was greater in steers fed diets supplemented with soybean meal, but whole tract digestibility was not affected by protein source. Total and bacterial CP flows to the abomasum were lower in steers fed diets supplemented with fish meal than in steers fed diets supplemented with heated soybean meal or the combination supplement. Dietary CP flow was 33.5% higher in steers fed diets supplemented with heated soybean meal than in steers fed diets supplemented with soybean meal, fish meal, or the combination supplement. Less essential and nonessential AA flowed to the abomasum and were absorbed from the small intestine of steers receiving diets supplemented with soybean meal. Digestibility of small intestine AA was 21.9% lower in steers receiving the soybean meal treatment. Abomasal flows of Met and Thr and absorption of Lys, Met, and Thr were increased in steers fed diets containing heated soybean meal, fish meal, and the combination supplement. These results suggest that the supply of AA deficient in microbial CP (Lys, Met, and Thr) can be increased and that absorbed AA balance can be changed markedly by selection of rumen escape protein supplements.     

Excretion of purine derivatives by Holstein cows abomasally infused with incremental amounts of purines

Five multiparous, ruminally cannulated Holstein cows (two lactating and three dry) weighing (X +/- SD) 667 +/- 35 kg were used to study the effect of abomasal purine infusion on the excretion of purine derivatives. Cows were fed corn silage four times daily at 90% of ad libitum intake (X = 9.16 kg of dry matter/d). Purines were infused into the abomasum as brewer's yeast suspensions in five incremental amounts (0 to 380 mmol/d) during five experimental periods according to a 5 x 5 Latin square design. Periods were 7 d; purine infusions were conducted during the last 4 d, and urine was collected during the last 3 d of each period. Ruminal purine outflow in all cows was measured during an experimental period immediately preceding and immediately following the five infusion periods and in each cow during the 0-mmol/d infusion period of the experiment. The relationship between total (milk plus urine) daily excretion of purine derivatives (allantoin plus uric acid) and total (abomasal infusion plus ruminal outflow) daily purine flow was quantified by linear regression analysis and was described by the relationship: Y = 0.856X + 103 (r2 = 0.93). The slope (0.856) indicated that 86% of purines that reached the omasum were excreted as purine derivatives. In the two lactating cows, urinary purine derivatives accounted for 98.4% of the total purine derivatives that were excreted. Ruminal flow of microbial CP can be estimated from the CP:purine ratio of ruminal microorganisms and the excretion of purine derivatives.     

PACAP stimulates pancreatic exocrine secretion via the vagal cholinergic nerves in sheep

The present study evaluates the possible role of the vagus nerves in mediating the stimulatory effect of PACAP-27, PACAP-38 and VIP on the exocrine pancreas, especially on enzyme secretion which is atropine sensitive in sheep. The animals were equipped with two cannulae into the common bile duct, a duodenal cannula, and a ruminal cannula under anesthesia. The bilateral cervical vagus nerves were coiled with a cooling device. In conscious animals, the peptides were infused intravenously for 10 min at 10 pmol kg(-1)min(-1) in phase II of the duodenal migrating motor complexes and the same peptide infusion was repeated in the reversible cooling blockade of the vagus nerves. Increment in fluid secretion was not significantly altered by the vagal blockade in all the peptide infusions, while increment in bicarbonate ion by only PACAP-27 was inhibited by the vagal blockade. Increments in protein and amylase output decreased significantly to 32.0+/-5.0 and 23.2+/-2.6% in PACAP27, and to 26.1+/-7.7 and 20.8+/-6.4% in PACAP-38 in the vagal blockade, but the increments by VIP did not decrease. These results demonstrate that circulating PACAP stimulates pancreatic enzyme secretion via the vagal cholinergic preganglionic neurons in sheep, suggesting the central action of PACAP.     

Normal abomasal electromyography and emptying in sheep and the effects of intraabomasal volatile fatty acid infusion

Electromyographic activity and emptying of the abomasum were studied in 3 sheep. Pacesetter potentials (PP), with a frequency of 6.06 +/- 0.05 (X +/- SEM) cycles/minute and propagated distally with an increased conduction velocity approaching the pylorus, were recorded from the distal 11 cm of the antrum. Spike burst and fused action potentials (AP) were superimposed on a variable percentage of PP. The aborad propagation of both types of AP was associated with abomasal emptying at the net rate of 12.61 +/- 1.38 (X +/- SEM) ml/minute. Intraabomasal infusion of 50 ml of a 300 mM solution of either acetic, propionic, or butyric acid was associated with a marked decrease in abomasal AP activity and in the emptying rate. Butyric acid was most effective, followed by propionic and acetic acids. The importance of the results in relation to the pathogenesis of left displaced abomasum (LDA) in dairy cows was noted.     

Duodenum as a immediate brake to gastric outflow: a videofluoroscopic and manometric assessment

BACKGROUND & AIMS: Duodenal infusion of HCl or lipid delays gastric emptying. The aim of this study was to assess whether this delay was in part caused by mechanical activity of the duodenum. METHODS: Synchronized videofluoroscopy and manometry was used in 8 volunteers (5 men and 3 women) to examine contractile and flow patterns during duodenal infusion of 0.9% NaCl, HCl, 5% NaCl, bile, and sodium oleate, each mixed with 20% (wt/vol) barium sulfate. RESULTS: Within 15-30 seconds of infusion, HCl and 5% NaCl induced frequent large-amplitude contractions greater tha those induced by 0.9% NaCl. Initially, there was rapid dispersion of HCl followed by prolonged, tonic occlusion of the duodenum. The duodenal diameter decreased compared with that observed during 0.9% NaCl or oleate infusion. In contrast, after infusion of oleate or bile, duodenal diameter increased and there were fewer, smaller-amplitude, nonpropagating contractions with prolonged retention of solutions. Barium (20%; wt/vol) did not influence the motility index of any solution. CONCLUSIONS: HCl and 5% NaCl may restrict gastric outflow by inducing tonic occlusion of the duodenum, whereas bile and lipid may delay clearance by decreasing duodenal tone and contractility. Thus, the duodenum may serve as an immediate brake to gastric outflow either by delaying clearance or by offering rapid tonic resistance.     

Gastroduodenal resistance and neural mechanisms involved in saline flow decrease elicited by acute blood volume expansion in anesthetized rats

We have previously demonstrated that blood volume (BV) expansion decreases saline flow through the gastroduodenal (GD) segment in anesthetized rats (Xavier-Neto J, dos Santos AA & Rola FH (1990) Gut, 31: 1006-1010). The present study attempts to identify the site(s) of resistance and neural mechanisms involved in this phenomenon. Male Wistar rats (N = 97, 200-300 g) were surgically manipulated to create four gut circuits: GD, gastric, pyloric and duodenal. These circuits were perfused under barostatically controlled pressure (4 cmH2O). Steady-state changes in flow were taken to reflect modifications in circuit resistances during three periods of time: normovolemic control (20 min), expansion (10-15 min), and expanded (30 min). Perfusion flow rates did not change in normovolemic control animals over a period of 60 min. BV expansion (Ringer bicarbonate, 1 ml/min up to 5% body weight) significantly (P < 0.05) reduced perfusion flow in the GD (10.3 +/- 0.5 to 7.6 +/- 0.6 ml/min), pyloric (9.0 +/- 0.6 to 5.6 +/- 1.2 ml/min) and duodenal (10.8 +/- 0.4 to 9.0 +/- 0.6 ml/min) circuits, but not in the gastric circuit (11.9 +/- 0.4 to 10.4 +/- 0.6 ml/min). Prazosin (1 mg/kg) and yohimbine (3 mg/kg) prevented the expansion effect on the duodenal but not on the pyloric circuit. Bilateral cervical vagotomy prevented the expansion effect on the pylorus during the expansion but not during the expanded period and had no effect on the duodenum. Atropine (0.5 mg/kg), hexamethonium (10 mg/kg) and propranolol (2 mg/kg) were ineffective on both circuits. These results indicate that 1) BV expansion increases the GD resistance to liquid flow, 2) pylorus and duodenum are important sites of resistance, and, 3) yohimbine and prazosin prevented the increase in duodenal resistance and vagotomy prevented it partially in the pylorus.     

Intestinal uptake and biliary excretion of the isoflavone genistein in rats

The intestinal absorption, biliary excretion and metabolism of genistein, a potent and specific protein tyrosine kinase inhibitor that occurs naturally in soy foods, was examined in anesthetized, adult female rats fitted with indwelling biliary cannulas. 4-14C-Genistein, when infused into the duodenum, was rapidly absorbed from the intestine, taken up by the liver and excreted into the bile as its 7-O-beta-glucuronide conjugate. Cumulative recovery of 14C-radioactivity in the bile over a 4-h period was 70-75% of the dose. When genistein was infused into the portal vein, it was also taken up efficiently by the liver, conjugated with glucuronic acid and transported into bile. However, portal blood collected after duodenal infusions of genistein contained mostly genistein 7-O-beta-glucuronide, suggesting that in vivo glucuronidation occurred in the intestinal wall rather than the liver. This was confirmed using everted intestinal sac preparations. Reinfusion of genistein 7-O-beta-glucuronide into the duodenum or into the mid small intestine resulted in its reappearance in the bile, albeit more slowly than when genistein was infused. Over a 4-h collection period, the cumulative recovery of 14C-radioactivity in bile was 27 and 70-75% of the administered dose for duodenal and ileal infusions, respectively. These data indicate that genistein is highly bioavailable in rats and because of its enterohepatic circulation may accumulate within the gastrointestinal tract.     

The contribution of serum phosphatidylcholine and lysophosphatidylcholine to lymph phosphatidylcholine

1. The contribution of serum phosphatidylcholine and 1-acyl lysophosphatidylcholine to chylomicron and mesenteric lymph lipoproteins of heavier buoyant density was studied in rats with catheters placed in the jugular vein, duodenum, common bile duct and mesenteric lymph duct. The effect of including 10 mM phosphatidylcholine in the triolein emulsion infused into the duodenum was also studied. 2. The intravenous infusion of phosphatidylcholine did not affect delivery of phosphatidylcholine into the lymph when phosphatidylcholine was included in the duodenal infusion. However, on intravenous lysophosphatidylcholine infusion, phosphatidylcholine transport into the lymph was increased both in chylomicrons and the other lipoproteins found in the lymph when phosphatidylcholine was included in the duodenal infusion. 3. The incorporation of serum phosphatidylcholine into chylomicron phosphatidylcholine was minimal and decreased further by intraduodenal phosphatidylcholine infusion. Incorporation into the heavier lymph lipoproteins was less than 20%. 4. The incorporation of serum lysophosphatidylcholine into chylomicrons was 17% at 4--6 h of infusion which was decreased by intraduodenal phosphatidylcholine as was the incorporation into the heavier lipoproteins of lymph. 5. It is concluded that serum phosphatidylcholine is a poor precursor of chylomicron phosphatidylcholine and that while lysophosphatidylcholine is a somewhat better precursor, its contribution to chylomicron phosphatidylcholine is limited by its serum concentration.     

Influence of duodenal slaframine infusion on site of nutrient disappearance from the digestive tract of steers fed a high-concentrate diet

The effect of duodenal slaframine (SF) infusion on site and extent of digestion was determined using four steers equipped with ruminal, duodenal, and ileal cannulas in a 4 x 4 Latin square. A 77% dry-rolled corn diet was provided in 12 equal portions daily at a DMI of 2.26% BW. Slaframine in a .9% saline excipient was infused into the duodenum every 12 h with total daily dose of 0, 30, 60, or 90 micrograms /kg of BW. Slaframine infusion had no effect on ruminal pH, ruminal NH3 N, or solids and liquids passage rate. Slaframine increased (linear, P < .10) total tract OM and starch disappearance and digestibility and tended to increase (linear, P = .14) total tract N digestibility. Ruminal starch disappearance tended to be decreased (quadratic, P = .16) by SF. Small intestinal OM digestibility was increased (linear, P < .10) but starch digestibility in the small intestine was not affected by SF. Increased total tract starch digestibility was caused by increased (quadratic, P < .10) starch fermentation in the large intestine. Ruminal feed N digestibility decreased at the intermediate doses of SF (quadratic, P < .10). Total N digestibility in the small intestine tended to be increased (cubic, P = .13) with 30 and 90 micrograms of SF/kg of BW. Decreased ruminal feed N digestion was compensated for by increased (quadratic, P < .10) small intestinal feed N disappearance for steers treated with intermediate doses of SF. The potential of SF to increase starch digestion in the rumen and small intestine seems to be limited.     

Development of a shortened version of the Breathing Problems Questionnaire suitable for use in a pulmonary rehabilitation clinic: a purpose-specific, disease-specific questionnaire

MMC-related retroperistalsis is a cyclical phenomenon in the duodenum linked to phase III. The aim of this study was to elucidate the direction of propagation of juxtapyloric duodenal pressure waves in the postprandial state in healthy humans and to compare with the contractions in the interdigestive phase II. Antroduodenal manometry was performed in 11 healthy subjects. Individual pressure waves propagating along a 6-cm duodenal segment were analysed with respect to the proportions of antegrade and retrograde propagation in the four duodenal subsegments (D1-D2) to (D4-D5), each subsegment being 15 mm. A test meal was given 30 min after a phase III had passed and motility recording continued for 60 min after the meal. During both the first and the second 30-min period of postprandial recording the proportion of retrograde pressure waves was larger just distal to the pylorus, (D1-D2), 40% (23-68) and 50% (23-68), respectively, compared to the distal part, (D4-D5), of the duodenal segment, 29% (12-30) and 10% (10-24), respectively (P < 0.05 and 0.01). In contrast, during late phase II of the interdigestive state antegrade pressure waves predominated in all four duodenal subsegments. We conclude that in the postprandial state a high proportion of the duodenal pressure waves (40-50%) is retrograde in the immediate juxtapyloric area while antegrade contractions predominate at a distance 5-6 cm distal to the pylorus. These manometric data together with recent observations of postprandial transpyloric liquid flow, indicate that retrograde duodenogastric propelling of contents may be an important determinant for the gastric emptying rate.     

In vitro metabolism of aniline by sheep intestine

1. The major metabolite after incubating aniline with sheep intestine was acetanilide. 2. Other metabolites detected in smaller amounts were 2-aminophenol, 4-aminophenol, 2-acetamidophenol and 4-acetamidophenol. 3. The rumen, abomasum duodenum, jejunum, ileum and colon were all able to acetylate aniline. 4. 4-Aminophenol, 4-aminobenzoic acid, 4-anisidine and 4-nitroaniline were also acetylated.     

Ultrasonography of the reticulum in cows

The reticulum and adjacent organs were examined ultrasonographically in 51 cows by use of a 3.5-MHz linear transducer applied to the ventral aspect of the thorax over the sixth and seventh intercostal spaces. Examination included assessment of the contour of the reticulum, of reticular contractions, and of the organs adjacent to the reticulum. The normal reticulum appeared as a half-moon-shaped structure with a smooth contour; it contracted at regular intervals and was situated immediately adjacent to the diaphragm and ventral portion of the abdominal wall when relaxed. Contents of the reticulum could not normally be imaged because of its partly gaseous composition. The ruminoreticular groove, craniodorsal blind sac of the rumen, and the ventral sac of the rumen were observed caudally. The distal aspect of the spleen and parts of the omasum, abomasum, and liver could be imaged. Reticular motility was characterized by a biphasic contraction pattern. Four biphasic reticular contractions usually were observed during a 4-minute period. During the first (incomplete) contraction, the reticulum contracted by a mean of 7.2 +/- 2.30 cm. There was then low-grade, incomplete relaxation of the reticulum, followed immediately by the second reticular contraction, during which the reticulum usually disappeared from the 17.5-cm-deep screen. The reticulum then reappeared in its normal position. The first reticular contraction lasted a mean of 2.6 +/- 0.33 seconds and the second contraction lasted 3.9 +/- 0.55 seconds. The mean interval between 2 biphasic contractions was 44.9 +/- 10.53 seconds. The speed of the first reticular contraction was 5.4 +/- 1.32 cm/s.(ABSTRACT TRUNCATED AT 250 WORDS)     

Vesicoureteral reflux following transurethral resection of bladder tumors

Duodeno-gastric reflux measured in 18 patients without gastrointestinal complaints showed a wide variation of regurgitation rates. Duodeno-gastric reflux was significantly diminished during duodenal acidification. The effect was more intense and lasted longer after olive oil infused intraduodenally, leading practically to a closed pylorus.     

Effects of intraduodenal air insufflation on sphincter of Oddi motility in conscious dogs

To investigate effects of intraduodenal air insufflation on sphincter of Oddi motility, manometric recordings were obtained during fasting from the sphincter and duodenum in four conscious dogs with duodenal cannula. At 40% of the mean cycle length of the migrating motor complex predetermined from baseline recording, 160 ml of air was injected into the duodenum. In both the sphincter and duodenum, air insufflation produced premature phase III-like activity in seven of 20 experiments (35%) or nonspecific excitatory reaction in eight (40%). In the remaining five experiments (25%), the sphincter exhibited a transient inhibitory response, while the duodenum showed the nonspecific excitatory reaction. Basal pressure of the sphincter increased immediately after air insufflation in 90% of the 20 experiments. The mean basal pressure increased from 12.3 +/- 1.6 mm Hg to 22.4 +/- 2.1 mm Hg (P < 0.0001) and minimum basal pressure from 2.9 +/- 0.9 mm Hg to 4.7 +/- 0.8 mm Hg (P < 0.001). These results indicate that intraduodenal air insufflation does affect motility of the sphincter of Oddi and duodenum in conscious dogs.     

Effect of duodenal glucose infusion on blood glucose concentration in endotoxin-treated calves

The effect of endotoxemia on the intestinal absorption of glucose was evaluated in nine experiments performed on seven 3- to 5-week-old calves fitted with a duodenal cannula. An intraduodenal glucose load trial (infusion of 2 g glucose/kg b.w. as a 10% aqueous solution through the cannula over 60 min) was conducted in a group of 5 calves three times during the 4-day period: 48 h before and at 2 and 24 h after i.v. injection of E. coli 0111:B4 endotoxin (LPS) at a dose of 0.1 microgram/kg b.w. Control calves were treated similarly but instead of glucose they were infused intraduodenally with deionised water at a volume of 20 ml/kg b.w. In trial with glucose load performed 48 h before LPS administration, blood glucose concentration increased during the absorptive phase from 4.32 +/- 0.32 mmol/l to 11.45 +/- 0.87 mmol/l at 60 min and then decreased to a minimum value of 3.16 +/- 0.51 mmol/l at 240 min. During the initial phase of endotoxemia, blood glucose concentration did not change from baseline values in both groups of calves. Glucose concentration in control calves started to decrease at 165 min reaching a minimum value of 1.39 +/- 0.17 mmol/l at 210 min and then increased to 2.44 +/- 0.11 mmol/l at 480 min after LPS administration. The intraduodenal infusion of glucose at 2 h after LPS administration resulted in an increase in blood glucose concentration during the absorptive phase only in one calf. Blood glucose concentration in this calf increased between 30 and 90 min reaching a maximum value of 7.19 mmol/l at 60 min, and then decreased to a minimal value of 0.94 mmol/l at 180 min after glucose load. In the remaining four calves in this group, blood glucose concentration ranged from 3.89 +/- 0.37 mmol/l to 4.48 +/- 0.45 mmol/l up to 120 min, and then steadily decreased to a minimal value of 2.41 +/- 0.41 mmol/l at 300 min. In trial with glucose load performed 24 h after LPS administration, the rate of entry of glucose into the circulation during the absorptive phase was similar to that observed in the trial performed 48 h before LPS administration. In conclusion, these results indicate that endotoxemia impairs the intestinal absorption of glucose in calves. The magnitude of the absorption disturbance may vary in individual calves, and the inhibitory effect of LPS on the intestinal glucose absorption lasts less than 24 h.     

Nonstructural carbohydrate and protein effects on rumen fermentation, nutrient flow, and performance of dairy cows

Four multiparous Holstein cows fitted with rumen and duodenal cannulas were used in a 4 x 4 Latin square with 20-d periods. Four diets were formulated for high and low rumen availabilities of nonstructural carbohydrate and protein. Cows were milked and fed three times daily. Milk production averaged 39 kg/d and was unaffected by treatment. Dry matter intake and 4% FCM production were increased by 1 kg/d for cows fed the low rumen-available nonstructural carbohydrate diets. Milk protein percentage was elevated when either the high rumen-available nonstructural carbohydrate or high rumen-available protein diets were fed. Low rumen-available protein diets increased duodenal passage of total essential AA but did not increase passage of Arg, Ile, and Met. Passage of bacterial N was highest (262 g/d) when high rumen-available nonstructural carbohydrate was combined with high rumen-available protein and was lowest when high rumen-available nonstructural carbohydrate was combined with low rumen-available protein (214 g/d). Diets with low rumen availabilities of protein were not advantageous, possibly because duodenal passage of one or more of the limiting AA was not increased. Passage of bacterial N to the duodenum was highest when rumen availabilities of both nonstructural carbohydrate and protein were high.