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Biomedical subjects

M Ivan

Publications and source records attributed to M Ivan.

At least 55 records · Page 3Linked to original sources
PubMed1990

Kinetics of intravenously administered vitamin E in sheep and its biliary excretion.

This report describes studies of vitamin E kinetics and biliary excretions of vitamin E in 7 sheep administered [3H]-d-alpha-tocopherol (2 microCi/kg body weight) intravenously. Blood samples were periodically withdrawn from the jugular vein and bile samples from a biliary fistula for 56 h after intravenous administration of the [3H]-d-alpha-tocopherol. The kinetic data were modelled as 2-exchanging compartments. Radiovitamin E was rapidly distributed into the peripheral compartment and was widely distributed throughout the body. A high level of radioactivity was recorded in the lung, liver, spleen and renals. The concentrations of d-alpha-tocopherol in bile and plasma did not run parallel. The pattern of biliary radioactivity concentration suggests a rapid biliary clearance.

Animals↗
PubMed1989

Effects of faunation and type of dietary protein on gastric solubility and liver content of copper in sheep.

Three experiments were conducted to determine the influence of the presence of protozoa on copper (Cu) metabolism in sheep fed corn silage or corn silage supplemented with casein, fish meal or soybean meal. For each diet, eight rams were kept fauna-free; eight additional rams were faunated and housed separately from them. The faunated rams in all treatments grew faster and consumed more feed and, consequently, more Cu. However, they had a lower (P less than .01) ruminal Cu solubility and accumulated less Cu in their livers than the fauna-free rams when fed corn silage alone or in combination with soybean meal (insoluble, ruminally degraded protein). Such effects were not significant when corn silage was supplemented with fish meal (protein resistant to ruminal degradation). The presence of ciliate protozoa in the rumen had no effect on the accumulation of Cu in the liver of sheep fed corn silage supplemented with casein (soluble, ruminally degraded protein) and produced conflicting results on ruminal Cu solubility. Hence, the effect of protozoa on Cu metabolism is indirect and depends on the type of protein present in the diet.

Animal Feed↗
PubMed1989

Digestibility measured by fecal and ileal collection in preruminant calves fed a clotting or a nonclotting milk replacer.

Eight Holstein male calves, each fitted with an ileal reentrant cannula at 7 to 10 d of age, were fed a milk replacer based on low heat skim milk powder with or without an oxalate-NaOH buffer known to prevent curd formation in the abomasum. The calves were used to study the effects of milk clotting on digesta flow at the ileum and apparent digestibility measured by fecal and ileal collection. Patterns of ileal flow of total digesta, DM, N, and fat were similar for the clotting and the nonclotting milk replacers. The apparent digestibility of DM and N was higher when measured by fecal than ileal collection for both milk replacers. Digestibility of DM was higher for the clotting than for the nonclotting milk replacer when measured by ileal collection. Clotting did not affect N digestibility measured by either fecal or ileal collection. The concentration of amino acids differed generally in the ileal digesta compared with concentration in feces. In the ileal digesta, some amino acids showed lower concentrations in the clotting milk replacer fed calves compared with those fed the nonclotting milk replacer. The coefficients of digestibility of each amino acid were similar when measured by either fecal or ileal collection. Clotting had no effect on amino acid digestibility measured by both fecal and ileal collection. The data suggest that fecal collection might indicate higher digestibility as compared with ileal collection and that the absence of milk replacer clotting does not affect ileal flow and digestibility of milk replacer N and fat.

Animals↗
PubMed1988

Digestibility and blood parameters in the preruminant calf fed a clotting or a nonclotting milk replacer.

Eight male Holstein calves 7 to 10 d of age were fed a milk replacer containing a skim milk powder subjected to low-temperature drying either with or without addition of an oxalate-NaOH buffer known to prevent curd formation. The calves were used in a completely randomized design to study the effect of milk clotting on digestibility and blood parameters. Plasma glucose and plasma insulin were similar (P greater than .05) for the clotting and the nonclotting milk replacers. For both treatments, concentrations of glucose and insulin reached a peak 2 h postfeeding (P less than .01). Plasma triglycerides were higher (P less than .01) postfeeding for the nonclotting than for the clotting milk replacer. Plasma essential amino acids and plasma urea were higher, whereas plasma calcium was lower, for the nonclotting milk (P less than .01). Digestibility of dry matter, protein and fat was similar (P greater than .05) between clotting and nonclotting milk. The dry matter content of feces was not affected by clotting (P greater than .05). The data are interpreted to indicate that clotting of the milk replacer modifies blood concentrations of triglycerides, essential amino acids and urea without changing the digestibility of the diet.

Amino Acids, Essential↗
PubMed1988

Effect of faunation on ruminal solubility and liver content of copper in sheep fed low or high copper diets.

Naturally fauna-free crossbred rams approximately 5 mo old, 49.3 +/- 1.88 kg live weight, were allotted to four groups. Two groups remained fauna-free, whereas the other two groups were faunated. A diet based on corn silage-soybean meal containing either a low or a high Cu concentration (7 or 15 micrograms/g dry matter) was fed ad libitum to the two groups for 197 d. The rams were killed at the end of the experiment and livers and ruminal contents were analyzed for Cu. Faunated sheep grew faster (P less than .01) and as a group consumed 1.53 kg diet dry matter daily compared with 1.34 for the fauna-free sheep. Faunated sheep had lower final liver Cu concentrations (P less than .01), total liver Cu per unit of Cu intake and ruminal Cu solubilities (P less than .01) when fed both low and high Cu diets. The relative hepatic Cu uptake was higher by rams fed the low Cu than by those fed the high Cu diet. The results are interpreted to show that faunation decreased the availability of Cu in sheep fed a corn silage-soybean meal diet. The magnitude of the effect was independent of the Cu concentration in the diet.

Animals↗
PubMed1987

Diethylsuccinate carboxylesterase activity in sheep poisoned by copper.

Plasma diethylsuccinate carboxylesterase activity in plasma was elevated within 7 days in 4 sheep which received 4 mg Cu per kg body weight in gelatin capsules daily for 100 days followed by the same amount of Cu as a drench until the haemolytic crisis commenced. Plasma aspartate amino-transferase and sorbitol dehydrogenase activities in plasma were not elevated in these animals until sixty days after the Cu treatment began. Activities of all 3 enzymes in the liver homogenates from copper-treated sheep were lower (P less than 0.01) than in control animals.

Animals↗
PubMed1987

Absorption and secretion of 65Zn in the stomach and intestinal tract of sheep exchanging digesta via duodenal re-entrant cannulas.

The absorption and secretion of 65Zn in the stomach and intestinal tract regions was studied in sets of two and three sheep which were exchanging digesta via re-entrant cannulas in the proximal duodenum. One sheep from each of the three three-sheep sets was dosed intraruminally with the radioisotope. One sheep from the three two-sheep sets received an intravenous dose. Measurements of 65Zn in blood plasma from intraruminally dosed sheep showed that there was no apparent absorption from the stomach region. Measurements from sheep receiving radioactive digesta intraduodenally showed that mean apparent absorption of 65Zn was 0.07 and mean true absorption was 0.103. There was a large variation in endogenous recycling of 65Zn into the stomach region. Secretion of 65Zn into the stomach and intestinal regions in the intravenously dosed sheep of the two-sheep sets was calculated on the basis of total recovery over 10 d in the digesta and faeces. The present study showed that for every 1 molecule Zn secreted into the stomach region, 2.1 molecules were secreted into the intestinal tract region.

Animals↗
PubMed1987

An oxalate-sodium hydroxide buffer to study the role of milk replacer coagulation in preruminant calves.

An oxalate-NaOH buffer, which prevents coagulation in the abomasum of young calves, was added to a nonclotting milk replacer based on high heat skim milk powder, to investigate effects of this buffer on digestibility and metabolism of dietary components. Twelve Holstein male calves were allotted at random in two groups of six animals each and fed the experimental milk replacers from 3 to 17 d of age. Digestibility of dry matter, protein, and fat was similar for both control and buffered milk replacers. Concentrations of plasma glucose, triglycerides, alpha-amino nitrogen, and urea were the same in animals receiving buffer treated milk replacer and control diets. The data suggests that this oxalate-NaOH buffer would be suitable to prevent milk clotting in studies dealing with the importance of coagulation in digestion and metabolism in preruminant calves.

Abomasum↗
PubMed1987

Duodenal flow of digesta in preruminant calves fed clotting or nonclotting milk replacer.

Four Holstein male calves each were fitted with a reentrant duodenal cannula and fed a low heat milk replacer with or without an oxalate-NaOH buffer known to prevent curd formation in the abomasum. Animals were used in a crossover design to study the effect of milk clotting on duodenal flow of DM, fat, protein, lactose, and Ca. Clotting affected the flow of DM, protein N, total N, and fat as shown by the more uniform gastric emptying of the clotting milk replacer compared with the nonclotting one. For both treatments, the flow rate of these components reached a peak 2 h after feeding. Clotting did not alter the flow rate of free amino N, lactose, and Ca. The cumulative flow of DM, lactose, and Ca was similar for the clotting and nonclotting milk replacers rising gradually during the first 4 h postfeeding and tending to plateau thereafter. The clotting milk replacer resulted in a more linear cumulative flow of fat, protein N, and total N than the nonclotting one. Proteolysis of milk protein in the abomasum was the same for the two milk replacers as indicated by the total flow of free amino N measured over 24 h. Data suggest that milk clotting modifies abomasal flow of milk constituents retained in the abomasal clot but does not alter the flow of constituents in the whey fraction.

Abomasum↗
PubMed1986

The alleviation of chronic copper toxicity in sheep by ciliate protozoa.

1. Rams, fauna-free from birth and initially of 48-65 kg live weight, were allocated to two groups of ten each and given a diet containing 14 micrograms copper/g dry matter; five additional rams were killed and their livers were analysed for Cu. 2. One group (faunated) was inoculated with a mixed population of ciliate protozoa, and contained between 60 x 10(5) and 195 x 10(5) protozoa/ml rumen fluid throughout the 184 d experiment. The other group remained fauna-free. Following blood sampling, three rams in each group were killed on day 63, two on day 125 and four on day 184. One sheep in each group died during the experiment. 3. Faunated rams showed higher weight gains and feed consumption than fauna-free rams. 4. Plasma Cu concentration (microgram/ml) increased from an initial 0.82 to a final 1.00 in faunated and 1.36 in fauna-free rams. Liver Cu concentration (micrograms/g dry matter) increased from an initial 745 to a final 962 and 1684 in faunated and in fauna-free sheep respectively, representing a 4.3-fold greater increase in the fauna-free than in the faunated group. The absorption and retention of Cu was 38-50% higher in the fauna-free than in the faunated rams. 5. It was suggested that rumen ciliate protozoa increased rumen production of sulphide (through increased breakdown of soluble proteins) which complexed part of the Cu, making it unavailable for absorption and utilization. Therefore, ciliate protozoa could determine susceptibility to chronic Cu toxicity in sheep.

Animals↗
PubMed1985

Effects of copper sulfate supplement on growth, tissue concentration, and ruminal solubilities of molybdenum and copper in sheep fed low and high molybdenum diets.

Each of four groups of six wethers were fed one of a low molybdenum, high molybdenum, low molybdenum plus copper sulfate, or high molybdenum plus copper sulfate corn silage-based diet for ad libitum intake for 221 days. Average daily gains and ratios of feed/gain were depressed for the high molybdenum diet as compared with the low molybdenum diet suggesting molybdenum toxicity in sheep fed the high molybdenum diet. This was alleviated partly by the copper sulfate supplement. The supplement also decreased solubility of both copper and molybdenum in the rumen but had no effect on copper concentration in blood plasma. Concentration of molybdenum was higher in both liver and kidney in sheep fed high-molybdenum diets as compared with low-molybdenum diets. Copper concentration was higher in kidneys of sheep fed high-molybdenum diets, but no difference was significant in liver copper between sheep fed diets high or low in molybdenum.

Animals↗
PubMed1983

The absorption of labelled molybdenum compounds in sheep fitted with re-entrant cannulae in the ascending duodenum.

The absorption of labelled molybdenum compounds was studied in pairs of sheep exchanging digesta via re-entrant duodenal cannulae. Tri- and tetrathiomolybdate 99Mo were rapidly absorbed from the rumen to circulate in plasma in a protein-bound and in a TCA-insoluble form. The compounds were also absorbed from the small intestine although some breakdown was evident. Initially, molybdate was poorly absorbed from the rumen but after several hours the concentration of protein-bound, TCA-insoluble 99Mo increased in plasma. This provides evidence of rumen thiomolybdate synthesis. The results indicate that thiomolybdates are absorbed directly from the rumen and despite the sensitivity of the compounds to acid, some absorption from the small intestine occurs after passage through the abomasum. Rumen absorption could be a contributory factor to ruminant sensitivity to the effects of Mo compounds.

Absorption↗
PubMed1983

Rumen ciliate protozoa: effects on digestion in the stomach of sheep.

Six wethers, each fitted with a rumen cannula and duodenal reentrant cannula, were used to study effects of ciliate protozoa on rumen digestion and metabolism. A corn: corn silage (1:1) diet was fed for two periods. During the first period, defaunation was attempted with nonyl phenol ethylene oxide. Defaunation was complete in three sheep and partial in the other three sheep in which a reduced population of a small Entodinium sp. was observed. During the second period the sheep were inoculated with ciliate protozoa, which established a large population in all animals. Apparent digestion in the stomach of organic matter and starch was higher when a large protozoal population was present. Amino acid flow through the duodenum was greater in defaunated animals. A large population of ciliates was associated with increases in both rumen ammonia and plasma urea but had a stabilizing effect on ruminal pH. Volatile fatty acids were higher in the defaunation period, but there were only small differences of molar proportions of the acids between the two periods. Effects of ciliate protozoa are related to animal performance.

Amino Acids↗
PubMed1982

Electromagnetic measurements of duodenal digesta flow in cannulated sheep.

Studies of duodenal digesta flow were made in sheep implanted with an electromagnetic flowmeter probe on the ascending and transverse duodenum and in sheep equipped in the ascending duodenum with a 'Y'-type or 'Ash'-type reentrant cannula or with a 'special simple' cannula. The flow of digesta was recorded between one week and 5 months after surgery. Patterns of the digesta flow through the individual systems of cannulation were compared with that of an implanted probe used as a reference. The order of similarity was Ash reentrant cannula less than Y reentrant cannula less than special simple cannula. The rate of digesta flow was similar for the probe, the Ash reentrant cannula with a one-way valve and the special simple cannula, but it was lower for the Y reentrant cannula due to frequent oscillation of the digesta. It was concluded that accurate quantitative electromagnetic measurements of duodenal digesta flow can now be performed in sheep fitted with the Ash-type reentrant cannula equipped with a one-way valve.

Animals↗
PubMed1982

The effects of thiosalicylic and hydroxyethylethylenediaminetriacetic acids on the absorption and excretion of 54Mn and 65Zn in the duodenally dosed sheep.

Nine sheep, each prepared with a single cannula in the ascending duodenum and a reentrant cannula in the terminal ileum were fed a purified diet deficient in manganese and zinc for a period of 1 month. The sheep were then divided into three equal groups and duodenally dosed with a mixture containing MnSO4, ZnSO4, 54Mn, 65Zn, and water (control), thiosalicylic acid (TSA), or hydroxyethylethylenediaminetriacetic acid (HEDTA). Blood and ileal digesta were sampled for 24 h and total urine and feces were collected for 14 days after dosing. Plasma uptake of 54Mn 1 h after dosing was more than threefold higher in the HEDTA-dosed sheep than in other sheep, indicating higher absorption of 54Mn. This was accompanied by a lower flow of 54Mn through the terminal ileum during the first 12 h after dosing. However, total 14-day urinary and fecal excretion of 54Mn and 65Zn were apparently higher in the HEDTA-dosed sheep than in other sheep, each approaching 100% of the dose. Excretion of 54Mn and 65Zn in TSA-dosed sheep was apparently higher than in control sheep. Plasma uptake 65Zn was higher in TSA-dosed sheep and lower in HEDTA-dosed sheep than in control sheep. However, total 14-day excretion of 65Zn in feces and urine was slightly higher in TSA-dosed than in control sheep. It was concluded that chelation of Mn and Zn with HEDTA or TSA would aggravate rather than alleviate a Mn or Zn deficiency in sheep.

Animals↗