Comparative effects of three phytases on the phosphorus and calcium use in the weaned piglet.

The addition of phytase to swine diets has generally increased P digestibility and consequently reduced fecal excretion of P. The comparative effects on P and Ca digestibility of dietary inclusion of 5 different phytases were evaluated in the weaned piglet. RONOZYME HiPhos is a microbial 6-phytase produced by synthetic genes, mimicking a gene from Citrobacter braakii, and was compared to the Escherichia coli-derived phytases Phyzyme and OptiPhos. In total, 112 weaned piglets (28 d old) were allocated to 8 equal groups of 14 animals. Pigs were fed for 29 d a vegetable-based diet without addition of mineral P [Co(-)] or this diet supplemented with 12 g/kg feed of CaHPO(4) [Co(+)] or with HiPhos at 1000 units/kg (H1000) or 1500 units/kg (H1500), Phyzyme at 500 units/kg (P500) or 750 units/kg (P750), or OptiPhos at 500 units/kg (O500) or 750 units/kg (O750). All phytases reduced (P < 0.05) fecal P concentration and excretion and increased (P < 0.05) P digestibility and apparent P absorption. The digestible P equivalences of H1000, H1500, P500, P750, O500, and O750 were 0.94, 1.50, 0.67, 0.92, 0.58, and 1.11 g of full available P/kg of feed, respectively. Calcium digestibility was increased (P < 0.05) and Ca excretion reduced (P < 0.05) by the phytases. The 3 phytase preparations increased digestibility and apparent absorption of P and Ca in weaned piglets fed a diet containing P exclusively from plant origin.

Effects of a 6-phytase on the apparent ileal digestibility of minerals and amino acids in ileorectal anastomosed pigs fed on a corn-soybean meal-barley diet.

Phosphorus of plant-based feedstuffs for monogastric animals is mainly in the form of phytic P, which has a very low bioavailability. The nondigested phytic P may contribute to P pollution. Furthermore, phytic acid may reduce digestibility of other minerals and protein. This study evaluated effects of the microbial 6-phytase RONOZYME HiPhos on apparent ileal digestibility of P, phytic acid, Ca, CP, energy, and AA in six 60-d-old ileorectal anastomosed pigs. In a duplicated 3 × 3 Latin square design, pigs had free access to alternatively a corn (Zea mays)-soybean (Glycine max) meal-barley (Hordeum vulgare)-based diet or this diet supplemented with RONOZYME HiPhos at either 500 units/kg (RH500) or 1000 units/kg (RH1000). Pigs fed diets supplemented with RH500 or RH1000 increased (P < 0.05) digestibility of P, Ca, and Lys. Pigs fed diet RH1000 increased (P < 0.05) digestibility of CP, total AA, indispensable AA, Glu + Gln, His, Gly, Ala, Tyr, Leu, Phe, and Met. Similar to growth trials with increased total tract digestibility of P and Ca, phytase increased apparent ileal digestibility of these indispensable minerals and phytate. The phytase increased digestibility of CP and indispensable AA indicating a better availability of plant-based proteins.

Characteristics of fungal phytases from Aspergillus fumigatus and Sartorya fumigata.

Aspergillus fumigatus phytase has previously been identified as a phytase with a series of favourable properties that may be relevant in animal and human nutrition, both for maximising phytic acid degradation and for increasing mineral and amino acid availability. To study the natural variability in amino acid sequence and its impact on the catalytic properties of the enzyme, we cloned and overexpressed the phytase genes and proteins from six new purported A. fumigatus isolates. Five of these phytases displayed < or= 2 amino acid substitutions and had virtually identical stability and catalytic properties when compared with the previously described A. fumigatus ATCC 13073 phytase. In contrast, the phytase from isolate ATCC 32239 ( Sartorya fumigata, the anamorph of which was identified as A. fumigatus) was more divergent (only 86% amino acid sequence identity), had a higher specific activity with phytic acid, and displayed distinct differences in substrate specificity and pH-activity profile. Finally, comparative experiments confirmed the favourable stability and catalytic properties of A. fumigatus phytase.

Effects of Aspergillus fumigatus phytase on phosphorus digestibility, phosphorus excretion, bone strength and performance in pigs.

Phytic-phosphorus has a very low bioavailability for monogastric animals and the non-utilized mineral contributes to the phosphorus (P) pollution problems. Phytases may ameliorate phytic-P antinutritive properties. However, phytases are very sensitive to the pelleting temperature commonly used for compound feed production and thus the challenge to produce a more thermostable phytase is very important. Pure Aspergillus fumigatus phytase (AFP) has the ability to refold into a native-like fully active structure after heat denaturation (20 min at 90 degrees C). The aim of the present work was to evaluate in vitro (in feed) and in vivo in young and in growing-finishing pigs the effects of AFP included in the feed at a level of 500 U/kg. Feed supplementation with AFP resulted in an in vitro phosphorus release of about three times higher than that obtained from the basal diets, irrespective of the pH value used for the determination (5.5 or 7). When the supplemented feed was steam pelleted at about 84 degrees C, the free P obtained after incubation at pH 5.5 represented 53% on an average of that obtained from the corresponding mash diets. The phytic-P-rich diets systematically induced hypophosphataemia, hypercalcaemia and hyperphosphatasaemia. The normal blood levels of P, Ca and alkaline phosphatase were restored by AFP. P apparent digestibility was significantly higher for the AFP diet (52.8 versus 30.8%). The improvement in Ca digestibility was not statistically significant. In all three in vivo experiments, AFP significantly decreased the P concentration in faeces (between 13 and 33%) as well as increased the growth rate and decreased the feed conversion ratio. Bone strength was significantly higher in the growing-fattening pigs fed on the AFP diet.

Effects of a microbial probiotic (Sporolactobacillus P 44) on postprandial porto-arterial concentration differences of glucose, galactose and amino-nitrogen in the growing pig.

Postprandial kinetics of porto-arterial concentration differences of glucose (G), galactose (Gal), L-lactic acid (LA), amino-nitrogen (AN) and urea (U) were studied in the pig after the ingestion of 10(7) colony-forming units (cfu) of Sporolactobacillus P 44 per g of feed. Eight fistulated pigs (portal vein and brachiocephalic trunk; mean body weight 70 +/- 4 kg) were used. The diet was based on skimmed milk (32%), barley (30%), maize (10%) and lactose (7%). The postprandial blood kinetics, 4 conducted per animal at 1-wk intervals, were studied during the 3 h following the ingestion of test meals of 1,000 g basal diet (BD) or the same diet supplemented by the bacteria (SD). The apparent absorption was estimated from the area between the portal and arterial concentrations. The areas of porto-arterial differences of G, Gal and AN of SD for the first 3 h after the meal were significantly higher after SD ingestion than those measured after BD intake. Plasma concentrations of U and porto-arterial differences of U and LA were not modified by the probiotic. These effects disappeared immediately after dietary supplement interruption, suggesting that added bacteria presence in the intestinal lumen was fundamental to the modifications observed in apparent absorption.

Splanchnic fluxes of amino acids after duodenal infusion of carbohydrate solutions containing free amino acids or oligopeptides in the non-anaesthetized pig.

Seven non-anaesthetized pigs (mean body-weight 64.6 kg) were used to study the intestinal absorption and hepatic metabolism of glucose and amino acids (AA) using carbohydrate solutions (maltose dextrin; 440 g/2 I), containing 110 g of either an enzymic milk-protein hydrolysate (PEP) with a large percentage of small peptides (about 50% with less than five AA residues) and very few free AA (8%) or a mixture of free AA (AAL) with an identical pattern, infused intraduodenally. Each pig was previously fitted under anaesthesia with electromagnetic flow probes around the portal vein and the hepatic artery, and with permanent catheters in the portal vein, carotid artery, one hepatic vein and the duodenum. Each solution was infused for 1 h after a fasting period (18 h) and each pig received both solutions at 8 d intervals. The observation period lasted 8 h. For most AA (his, lys, phe, thr, arg, tyr, pro) the absorption rate after infusion of PEP was significantly higher than after that of AAL during the 1st hour, but the differences quickly disappeared. After 8 h, the only differences concerned his and tyr (PEP > AAL) and met, glu and asp (AAL > PEP). There was a large uptake of blood AA by gut-wall cells, higher after AAL infusion than after PEP infusion, particularly for branched-chain AA (BCAA). The absorption of ammonia-nitrogen after both infusions was equivalent to two-thirds of urea-N passing from blood to intestinal tissues and lumen. Glucose absorbed within 8 h represented only 76% (PEP) or 69% (AAL) of the infused amounts. The cumulative hepatic total AA (TAA) uptake increased from 13 to 27% of the infused amounts between the 1st and the 8th hour after PEP infusion, and from 8 to 31% after AAL infusion. Most essential AA were largely taken up by the liver, with the exception of met (PEP) and thr and of BCAA, which were poorly retained for both solutions; there was a high uptake of ala and gly, and a release of asp, glu, and gln. Urea-N released by the liver within 8 h was equivalent to 23-25% absorbed amino-N and to around 1.5 times ammonia-N taken up by the liver within 8 h. Glucose was highly taken up by the liver during the first hours then released, the total uptake within 8 h representing about half the absorbed amount.(ABSTRACT TRUNCATED AT 400 WORDS)

The effects of intravenous urea infusions on portal and arterial plasma ammonia and urea enrichment of jejunal and colonic infusions. Acute experiments with growing pigs.

Six pigs (49-69 kg) were anaesthetized and fitted with cannulas in the brachiocephalic artery and portal and jugular veins. In addition, inlet-outlet perfusion cannulas were placed in segments of the small and large intestine. Intravenous infusion of urea for 2 h increased arterial plasma urea from a base-line level of 176 (SE, 51) mg/l up to 292 (SE, 67) mg/l after 5 h. During this rise portal ammonia levels remained fairly constant, with minimum and maximum values of 1.2 (SE, 0.3) and 1.7 (SE, 0.6) mg/l, respectively. The average amount of urea recovered in perfusates from small- and large-intestinal segments were 141.4 and 43.8, respectively (p less than 0.001), when expressed as micrograms/g tissue/30 min. It thus appears as if the portal blood is not an important carrier of ammonia liberated from the hydrolysis of urea and that the gastrointestinal tract is differentially permeable to urea at different levels.

Glucose absorption, hormonal release and hepatic metabolism after guar gum ingestion.

Six non-anaesthetized Large White pigs (mean body weight 59 +/- 1.7 kg) were fitted with permanent catheters in the portal vein, the brachiocephalic artery and the right hepatic vein and with electromagnetic flow probes around the portal vein and the hepatic artery. The animals were provided a basal none-fibre diet (diet A) alone or together with 6% guar gum (diet B) or 15% purified cellulose (diet C). The diets were given for 1 week and according to a replicated 3 x 3 latin-square design. On the last day of each adaptation period test meals of 800 g were given prior to blood sampling. The sampling was continued for 8 h. Guar gum strongly reduced the glucose absorption as well as the insulin, gastric inhibitory polypeptide (GIP) and insulin-like growth factor-1 (IGF-1) production. However, the reduction in peripheral blood insulin levels caused by guar gum was not associated with a change in hepatic insulin extraction. IGF-1 appeared to be strongly produced by the gut. The liver had a net uptake of the peptide. Ingestion of guar gum increased the hepatic extraction coefficient of gut produced IGF-1. Guar gum ingestion also appeared to decrease pancreatic glucagon secretion. Cellulose at the level consumed had very little effect on the parameters considered. It is suggested that the modulation of intestinal mechanisms by guar gum was sufficient to mediate the latter internal metabolic effects.

Interorgan movements of amino acid in the pig: effects of dietary fibres.

Six non-anaesthetized Large White pigs (mean body weight 59 ± 1.7 kg) were fitted with permanent catheters in the portal vein, the brachiocephalic artery and the right hepatic vein as well as with electromagnetic flow probes around the portal vein and around the hepatic artery. The animals were given a basal none-fibre diet (diet A) alone or together with 6% guar gum (diet B) or 15% purified cellulose (diet C). The diets were given for one week and according to a replicated 3 × 3 latin square design. On the last day of each such adaptation period test meals of 800 g were given prior to blood samplings. These samplings were continued for 8 h. Guar gum strongly reduced the amino acids (aa) and urea absorption as well as the hepatic production of urea. The aa profile of the absorbed mixture was not strongly modified by guar gum ingestion as well as the profile of the hepatic aa uptake. Cellulose at the consumed level had very few effects on the considered parameters.It is suggested that the modulation of intestinal mechanisms by guar gum was sufficient to mediate the latter internal metabolic effects.

Hepatic and portal-drained viscera balances of amino acids, insulin, glucagon and gastrin in the pig after ingestion of casein or rapeseed proteins.

Hepatic and intestinal balances of amino acids, insulin, glucagon and gastrin were studied in 6 non-anaesthetized Large White pigs (mean body weight 64 +/- 4.8 kg) after ingestion of casein or rapeseed proteins. The animals were fitted with permanent catheters in the portal vein, the brachiocephalic artery and the right hepatic vein. In addition, 2 electromagnetic flow probes were implanted, one around the portal vein and the other around the hepatic artery. After a preliminary adaptation to each diet the animals received at 1-wk intervals and according to a double latin square design, 3 test meals of 800 g each, one containing 23.2% of rapeseed concentrate (diet RA 12) and the others 13.9 or 27.8% of hydrochloric casein (diets CA 12 and CA 24). Each observation period lasted 12 h. Amino acids from all diets were very well absorbed. In 12 h, the absorption of total amino acids as a percentage of the ingested quantities was 99% for CA 12, 102% for CA 24 and 104% for RA 12. Hepatic uptake of total amino acids in 12 h expressed as a percentage of the absorbed quantities was 13% for CA 12, 66% for CA 24 and 25% for RA 12. Differences in the hepatic extraction rate of essential amino acids appeared between the 2 levels of casein ingestion and for Arg between the 2 protein sources. Whatever the nature of the ingested protein or the level of casein, the liver showed a net production of Asp and Glu. The production and hepatic balance of insulin were the lowest after ingestion of RA 12. No differences were noted in the same parameters for glucagon and gastrin. Independently of the nutritional situation, the hepatic extraction rate of insulin appeared to be higher than those of glucagon and gastrin. Our results showed that the nature as well as the level of dietary proteins have large effects on the sequence and volume of absorptive phenomena, the hepatic metabolism of nutrients, the production of gastrointestinal hormones and the non-hepatic tissue disposal of absorbed nutrients.

Net appearance of amino acids in portal blood during the digestion of casein or rapeseed proteins in the pig.

The kinetics of appearance of amino acids (AA) in portal blood following the ingestion of casein or rapeseed protein were compared. Six pigs, fitted with permanent catheters in the portal vein and in the carotid artery, as well as with an electromagnetic flow probe around the portal vein, received three 800 g test meals, one containing 12% rapeseed proteins (RA12) and the others containing 12% and 24% casein (CA12 and CA24), at 1-week intervals and according to a double Latin square design. Portal and arterial blood samples were collected and portal blood flow rate was recorded for 8 h after the test meals. At the end of measurement, an average of 76.1 +/- 5.6% (mean +/- SEM) of total AA from the CA24 diet had appeared in portal blood, compared with 94.3 +/- 10.4% for the CA12 diet and 103.5 +/- 12.6% for the RA12 diet. Similar results were obtained for essential AA. Differences were found in the kinetics of appearance of individual AA. Eight hours after the meal, 79% of lysine, 84% of methionine, and 73% of valine from the CA24 diet had appeared in portal blood compared, respectively, with 100, 89, and 83% from the CA12 diet and 99, 86, and 106% from the RA12 diet. Arginine from rapeseed had a net appearance level lower (82%) than the overall mixture of essential AA. With casein diets, the net appearance of arginine reached 97% (CA12) and 82% (CA24). Following the ingestion of rapeseed proteins, there seemed to be a significant appearance of endogenous AA in portal blood.(ABSTRACT TRUNCATED AT 250 WORDS)

Total pancreatic insufficiency in pigs: a model to study intestinal enzymes and plasma levels of digestive hormones after pancreatic supplementation by a whole pancreas preparation.

Oral pancreatic enzyme replacement therapy generally benefits patients with severe pancreatic deficiency. However, the fate of oral pancreatic supplements in the digestive lumen and their possible effects on circulating gut hormones are only partially known. The purpose of this article is to validate an experimental model that produces total pancreatic insufficiency in pigs, and to study the fate of orally administered Eurobiol, a whole pancreas lyophilized preparation, and its effects on circulating plasma levels of five digestive hormones. Pancreatic insufficiency was created by pancreatic duct ligation, and the duodenal, jejunal and ileal contents were sampled through cannulas before a normal meal and 0.5-24 h later. Blood samples were taken at the same times, and plasma neurotensin, pancreatic polypeptide, secretin, cholecystokinin (CCK), and gastrin were measured. In pigs with pancreatic insufficiency, Eurobiol, given during the meal, induced a significant increase in all enzyme activities in the duodenum and the jejunum, and in the levels of amylase, trypsin, and chymotrypsin in the ileum, relative to placebo. In the duodenum, the peak concentrations of enzyme activities were 19, 11, 17, and 29% (p less than 0.001) of the postprandial peak activities measured in control pigs with an intact pancreas for lipase, amylase, trypsin, and chymotrypsin, respectively. In the jejunum, the same activities were, respectively, 30, 11, 25, and 36% (p less than 0.01-0.001) of normal peaks. In pigs with pancreatic insufficiency, basal and integrated meal-stimulated neurotensin levels were increased; basal, peak, and integrated meal-stimulated pancreatic polypeptide and secretin levels were increased, whereas gastrin and CCK were not different from controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Relation between in vitro and in vivo assessment of amino acid availability.

Even though the availability of dietary amino acids is the result of integrated phenomena of digestion, absorption and transport, it may be mainly affected by the stage of luminal digestion. In this case, amino acid availability could be predicted by an in vitro method designed to reproduce in vivo proteolysis conditions. In order to check this hypothesis, the essential amino acid (EAA) profiles of digesta collected at 8 intervals during a 24-h in vitro enzymatic proteolysis of casein and rapeseed proteins were compared to the pattern of appearance of dietary EAA in portal vein of pigs fed the same proteins, determined at each hour over a 8-h postprandial period by coupling blood flow rate with porto-arterial differences in plasma EAA concentrations. Comparisons of in vitro and in vivo data first bore on overall EAA profiles measured at each interval, and then on the individual kinetics of each EAA. Regarding total profiles, the highest correlations for casein (r: 0.80-0.98) were found when comparing EAA patterns determined during the first half of in vitro digestion and in vivo absorption periods. Similar r values were obtained with rapeseed proteins, but over longer periods of measurement. Concerning individual kinetics, the highest correspondences were found with rapeseed proteins, with 5 out of 9 EAA (methionine, isoleucine, leucine, phenylalanine and arginine) having their in vitro sequence of release significantly correlated with their in vivo sequence of absorption. With casein, correlations were significant for threonine, valine, isoleucine and leucine. These results suggest that sequential hydrolysis in the digestive tract, as reproduced by the in vitro technique, is a key determinant of amino acid appearance in the portal blood to a degree varying with the protein source and with the nature of the amino acid.

Uterine metabolism of the conscious gilt during late pregnancy.

The present study provides some metabolic features of the gravid uterus in the nonanesthetized gilt during the last fourth portion of pregnancy. Substrate and oxygen arteriovenous differences across the uterus were determined in eight gilts with chronically implanted arterial and uterine venous catheters. Glucose represents the main substrate taken up by the conceptus and glucose extraction amounts to 8.3 +/- 0.5%. By contrast, there is a constant release of lactate from the pregnant uterus. The coefficient of extraction of oxygen is 20.2 +/- 1.9%. Glucose plus lactate/oxygen quotient is high (1.3 +/- 0.2), suggesting that glucose alone is sufficient to account for the oxidative metabolism of the pig uterus. Nonesterified fatty acid and ketone body are not significantly extracted by the pig uterus whereas a significant amino acid extraction occurs in late pregnancy. Uterine uptake of amino acids depends on maternal arterial concentrations and a great part (78%) of this uterine uptake is represented by neutral amino acids and especially glutamine.

Effect of feed intake level in late gestation on arterial blood concentrations of energy substrates, insulin and glucagon in the chronically catheterized gilt.

The aim of the present work was to study, in the unstressed catheterized gilt, the effect of pregnancy on arterial substrate and pancreatic hormone concentrations in relation to the feed intake level. The experiments were performed on 14 pregnant gilts during the last month of gestation and 5 non pregnant gilts after cannulation of one carotid artery. Blood samples have been collected regularly after an overnight fast. After catheterization of the pregnant gilt, a 4 day-period is required to obtain steady-state conditions. As compared with non-pregnant animals fed on the same standard conditions (i.e. 2 kg/d: crude protein: 130 g/kg; digestible energy: 12.8 MJDE/kg), pregnant gilts exhibit similar and constant blood glucose, lactate, ketone body and plasma free fatty acid concentrations. By contrast, blood alanine concentrations progressively increases. A reduction of the feed intake level by 40% does not modify the blood glucose concentrations but leads to reduce blood lactate and alanine concentrations. On the contrary, plasma free fatty acid levels rise progressively with a limited increase in blood ketone body concentrations. While plasma glucagon concentrations are constant whatever the physiological state or the feed intake level, plasma insulin levels progressively decrease in the pregnant gilt. These data are discussed to display some aspects of the adaptation of the maternal metabolism in the gilt in late gestation.

[Comparison of 2 technics (ninhydrin vs. TNSB) for estimating circulating amino acid nitrogen, applied to the study of the intestinal absorption of solutions of free amino acids or small peptides]. / Comparaison de deux techniques d'estimation (ninhydrine vs TNBS) de l'azote des acides aminés circulants, appliquées à l'étude de l'absorption intestinale de solutions d'acides aminés libres ou de petits peptides.

The intestinal absorption of nitrogen from amino acids present in a solution of small peptides or of free amino acids with the same pattern, perfused intraduodenally, has been studied using two analytical techniques [2, 4, 6 trinitrobenzene-1-sulfonic acid (TNBS) after dialysis of the blood vs ninhydrine after chromatography] to determine post-perfusion porto arterial differences and to measure blood flow rate in the portal vein. The results obtained on blood nitrogen level with the chromatographic method were always higher than those obtained using the TNBS method. The differences in the values varied from 8 to 24% according to post-perfusion time and to blood sample origin (arterial or portal). On the contrary, the absorbed amounts of nitrogen measured by either analytical technique were not very much different: no significant and systematic deviation was found between the two. The TNBS method is thus useful as a preliminary approach to very elaborate studies on intestinal absorption. In these conditions, the nitrogen of amino acids from duodenally-perfused small peptides was absorbed earlier and more rapidly than that from a perfusion of a solution of free amino acids. The amount of nitrogen appearing in the portal vein five hours after perfusion exceeded the perfused amount owing to considerable recycling of endogenous nitrogen.

Adaptation of pancreatic lipase to the amount and nature of dietary lipids in the growing pig.

The purpose of the present study was to examine the adaptation of pancreatic lipase to the amount and nature of dietary lipids in the growing pig. Thirty pigs were distributed into three groups of 10 animals each. They were fed the same amount (1.5 kg/pig/day) of either diet C (3.5% lard, 3.5% sunflower oil, 67.7% starch), diet L (21% lard, 33.2% starch) or diet SO (21% sunflower oil, 33.2% starch) for 12 days. The diets were isoenergetic and isonitrogenous. Pancreas weight relative to live-weight was highest in group L. The pancreatic lipid content of the latter group exceeded that of groups C and SO by 53 and 39%, respectively. The pancreatic protein content was similar in the three groups. The specific lipase activity of pancreatic tissue (U per mg of protein) in group SO was about 1.6-fold higher than that of group L and about 3-fold higher than that of group C (31.9, 19 and 11.6, respectively). Specific amylase activity was higher in animals of group C than in those of the other two groups (C : 1689; L : 1112; SO : 984), whereas no difference was observed in chymotrypsin activity. Specific trypsin activity was lowest in group L. These results confirm the adaptation of pancreatic lipase and amylase to their respective substrates. Furthermore, it appears that lipase activity was more or less affected by the degree of unsaturation of lipids and that it was much higher for the same amount of triacylglycerols when the latter were rich in unsaturated fatty acids. The mechanisms involved have not been determined yet, but the possible physiopathological consequences of the increased pancreatic lipid content observed in pigs receiving triacylglycerol-rich diets (including especially saturated fatty acids) should be considered.

Effect of intragastric triglyceride administration on glucose homeostasis in newborn pigs.

The fasting hypoglycemia (1.78 +/- 0.29 mmol/l) which develops in 48-h-old pigs is partially reversed (3.85 +/- 0.55 mmol/l) after gastric administration of long-chain triglycerides (LCT). The increase in blood glucose induced by LCT feeding was not secondary to a decreased glucose utilization because glucose disappearance rate increased in LCT-fed piglets but resulted from a twofold increase in glucose appearance. By using the crossover-plot technique, the stimulation of hepatic gluconeogenesis induced by LCT feeding has been localized at 1) the level of pyruvate carboxylase owing to the twofold increase in hepatic acetyl-CoA concentration and 2) the level of glyceraldehyde-3-phosphate dehydrogenase secondary to the increase in reducing equivalents (NADH), which displaces this equilibrium reaction in the direction of gluconeogenesis. As blood lactate, pyruvate, and alanine concentrations increased after LCT feeding, the possible effects of LCT on pyruvate dehydrogenase in peripheral tissues are discussed. These data demonstrate that fatty acids stimulate hepatic gluconeogenesis in 48-h-old fasting piglets and underline the role of fat provision in the regulation of glucose homeostasis during the neonatal period in the pig.

[Regulation of pancreatic secretion by negative feedback and blood gastrointestinal hormones in the pig]. / Régulation de la sécrétion pancréatique par rétroaction négativehormones gastro-intestinales plasmatiques chez le porc.

The aim of this study was to determine the rate of circulating gastrointestinal hormones in pigs when pancreatic secretion was re-introduced or removed from the duodenal lumen. Permanent fistulas were fitted into the pancreatic duct and duodenum of 16 pigs, and catheters were introduced into the portal vein and a jugular vein as well. Plasma hormone content was determined at different times during two periods of 30 and 60 min each, when the juice was returned to the pigs; these two periods included a 120-min interval when the juice was not reintroduced into the intestinal lumen. When the pancreatic juice was not returned to the pigs, plasma secretin content rose significantly in the portal blood (+ 42.8% at min 15; +52.5% at min 30; +31% at min 60 and +27% at min 120) and in the peripheral blood (+36.4% at min 30; +18.9% at min 120) compared to the mean values recorded during intraduodenal re-introduction of the secretion. In parallel, the volume of juice secreted and protein output increased significantly but their concentration did not. When the pancreatic juice was removed the mean cholecystokinin level in the portal vein did not change significantly, except at min 30 when its value was 32% higher than the mean during the periods of restitution. Cholecystokinin in the peripheral blood was not affected by removing the pancreatic juice from the intestinal lumen. The mean plasma levels of gastrin, somatostatin, VIP and PP in the portal and peripheric blood were unaltered. These results suggest that in pigs secretin may have an important role in the regulation of pancreatic secretion by negative feedback.

[Comparative kinetics of appearance in the portal vein of alpha-aminated nitrogen from mixtures of small peptides of free amino acids of the same composition introduced in the duodenum of conscious pigs]. / Cinétique comparée d'apparition dans la veine porte de l'azote alpha-aminé provenant de mélanges de petits peptides ou d'acides aminés libres de même composition introduits dans le duodenum chez le porc éveillé.

The quantitative kinetics of appearance of amino acids (a.a.) in the pig portal vein was studied in 6 animals for 5 hrs. after duodenal perfusion of an enzymatic hydrolysate of milk proteins or a solution of free a.a. of the same composition. Each product was given in two quantities (55 and 110 g). The quantities of a.a. appearing in the portal vein were higher after perfusion of the hydrolysate than after that of the free a.a., independently of the time after the perfusion. Thus, nitrogen present in the small intestine as small peptides is absorbed more quickly than when it is present as free amino acids.