Biomedical subjects

R E Austic

Publications and source records attributed to R E Austic.

At least 19 recordsLinked to original sources

PubMed1998

Transamination of 2-oxo-4-[methylthio]butanoic acid in chicken tissues.

The keto acid 2-oxo-4[methylthio]butanoic acid (OMTB) is an intermediate in the conversion of synthetic feed grade methionine sources to L-methionine in vivo in poultry and other animals. Because methionine sources are utilized by the chick with considerably less than 100% efficiency as sources of L-methionine, it is important to determine what metabolic process may limit the utilization of these sources. Because OMTB is converted to L-methionine by transamination, a study was conducted to determine which amino acids might serve as nitrogen donors in the conversion of OMTB to L-methionine in the chicken. Dialyzed tissue homogenates, mitochondria, and cytosol from liver, kidney, intestine, and skeletal muscle were incubated with OMTB and individual L-amino acids (isoleucine, leucine, valine, glutamic acid, aspartic acid, alanine, glutamine, asparagine, and phenylalanine) and the methionine that accumulated was determined by ion exchange chromatography. Tissues differed in the conversion of OMTB to methionine: kidney was most active, liver and intestinal mucosa were intermediate, and skeletal muscle had lowest activity. All amino acids supported methionine synthesis. Branched-chain amino acids and glutamic acid were the most effective substrates in tissue cytosols except in intestinal mucosa, in which asparagine was also effective. The preferred substrates in mitochondria were glutamate in liver mitochondria, isoleucine and alanine in kidney mitochondria, and branched-chain amino acids and glutamic acid in skeletal muscle mitochondria. All amino acids except alanine supported methionine synthesis from OMTB in mitochondria of intestinal mucosa. We conclude that a wide variety of amino acids can serve as substrates for transamination of OMTB in the chicken, and that the availability of nitrogen donors is unlikely to be a limiting factor in the conversion of OMTB to methionine.

Amino Acids↗

PubMed1997

Dietary protein and amino acid levels alter threonine dehydrogenase activity in hepatic mitochondria of Gallus domesticus.

Experiments were conducted to determine if hepatic threonine dehydrogenase (TDH) activity is influenced by dietary protein or specific amino acid concentrations. In an initial experiment, young chicks were deprived of feed for 60 h or had access for 72 h to a 22% protein basal diet, a protein-free diet or a 51% high protein diet. TDH activity was determined as aminoacetone and glycine accumulation during incubation of liver mitochondria. TDH activity was significantly (P < 0.01) lower in chicks fed the protein-free diet and significantly greater in chicks fed the high protein diet compared with chicks fed the basal diet. Food deprivation had no effect on TDH activity. A second experiment was conducted using the 22 and 51% protein diets, the 22% protein diet plus 1.14 g/100 g diet threonine (equivalent to the free plus protein-bound threonine content of the high protein diet), and the 51% protein diet containing 0.15 g/100 g diet less threonine. TDH was increased in chicks fed either high protein diet (P < 0.05). There were no significant differences in TDH activity, however, between chicks fed the basal diet and the threonine-supplemented diet or between chicks fed the two high protein diets. In two other experiments, the activity of TDH was investigated in chicks fed for 9 d dietary supplements of either serine or glycine (5.5 or 4 g/100 g basal diet, respectively). The supplements were added to the basal diet or the basal diet imbalanced by the addition of 6% branched-chain amino acids. Neither the serine nor the glycine supplement significantly altered TDH activity or the increased activity associated with a branched-chain amino acid-induced threonine imbalance. The results suggest that hepatic TDH activity is influenced by protein level or other amino acids more than by threonine itself.

Alcohol Oxidoreductases↗

PubMed1994

Dietary threonine imbalance alters threonine dehydrogenase activity in isolated hepatic mitochondria of chicks and rats.

Experiments were conducted on chicks and rats to determine whether hepatic threonine dehydrogenase activity is modified by the consumption of a threonine-imbalanced diet and to determine the tissue distribution of this enzyme. Threonine imbalances were created by supplementing basal diets with branched-chain amino acids (6 g/100 g diet for chicks) or a mixture of indispensable amino acid (5.6 g/100 g diet for chicks and 5.4 g/100 g diet for rats). Chicks fed threonine-imbalanced diets consistently had twice the hepatic threonine dehydrogenase activity of those fed the basal diet when measured in one experiment at 24 h and in two experiments at 216 h (P < 0.05). Rats received the experimental diets for 12 or 24 h in one experiment and for 12, 24, 72 or 168 h in another experiment. In the first experiment, rats fed the threonine-imbalanced diet had significantly greater hepatic threonine dehydrogenase activity (P < 0.05) at 12 h but not at 24 h. In the other rat experiment, threonine dehydrogenase activity in the rats fed the threonine-imbalanced diet was significantly greater than in controls at 72 h, but tended to be lower at 168 h, which coincided with the adaptation of the rats to the imbalanced diet. Threonine dehydrogenase activity was widespread in tissues of both species. The results indicate that alterations in hepatic threonine dehydrogenase activity occur in chicks and rats subjected to threonine imbalance.

Acetone↗

PubMed1994

Threonine requirement and threonine imbalance in broiler chickens.

Three experiments were conducted to determine the effect of excess dietary protein on threonine requirement of broiler chicks to 14 d of age (Experiments 1 and 2) and to determine the threonine requirement from 16 to 28 d of age (Experiment 3). Two dietary protein levels were used in Experiments 1 and 2:20% CP in a threonine-limiting basal diet containing wheat, peanut meal, and selected amino acids and 25% CP in the same basal diet supplemented with a mixture of amino acids lacking threonine. A threonine-limiting 25% CP diet based on corn, soybean meal, and amino acids was also included in Experiment 2. The threonine requirement of chicks from 16 to 28 d of age was determined using a single CP level (20%) in Experiment 3. Threonine requirements were estimated by broken line regression analysis of weight gain and feed efficiency. Threonine requirements based on weight gain were 7.7 and 6.7 g/kg of diet in Experiments 1 and 2, respectively, for chicks receiving the 20% CP diets. The requirements increased to 8.6 and 8.2 g/kg, respectively, for chicks fed the 25% CP diets based on wheat, peanut meal, and amino acids. The requirement for maximum weight gain of chicks fed 25% CP based on corn, soybean meal, and amino acids was 7.7 g/kg of diet. However, chicks ate more of this diet, and on an intake basis, the requirement of the chicks fed the 25% CP diets based on wheat and peanut meal or corn and soybean meal did not differ. Requirements based on feed efficiency were equal to, or less than, those based on weight gain in Experiments 1 and 2. Body moisture and fat contents were affected by dietary CP level (P < .01), ingredient composition (P < .01), and threonine content (P < .05). Estimates of threonine requirements based on regression analysis of plasma threonine concentrations were higher than those based on weight gain or feed efficiency. The threonine requirements of chicks fed a 20% CP diet from 16 to 28 d of age were 6.3 and 6.9 g/kg of diet based on weight gain and feed efficiency, respectively.

Animal Feed↗

PubMed1994

Environment-immune interactions.

The need for effective immune function for the maintenance of health has been clearly established in both agriculturally significant animal species and humans. Intensive agricultural practices present production species with numerous disease challenges during the rearing period. Environmental factors represent a ubiquitous, yet frequently manageable, category of immunomodulators that can influence immune performance and ultimately disease susceptibility or resistance. However, strategies for assessing overall immune potential have not been widely implemented for agricultural species. This is in contrast to the use of immune evaluation for human health considerations. Immune assessment relative to environmental-immune interactions can produce benefits in two areas. First, the efficiency of the production operation can be enhanced. Second, the welfare of the animals during the production cycle can be optimized. This paper presents an overview of environmental factors known to influence the immune function of poultry and the opportunities to manage environmental factors to benefit the health of the animals. In addition, the paper discusses the status of immunological assessment for humans and laboratory animals and proposes potential immune assessment panels that could serve as a tool to optimize the environmental management of poultry populations.

Animal Husbandry↗

PubMed1993

Effects of selected minerals on acid-base balance and tibial dyschondroplasia in broiler chickens.

Experiments were conducted to determine the relative acidogenicities of several anions, including chloride, sulfate, and mono-, di-, and tribasic phosphate in commercial broiler chickens. Graded levels (80 and 160 meq/kg of diet in two experiments; 50, 100, and 150 meq/kg in a third experiment) of all anions were substituted as calcium salts on a molar equivalent basis for calcium carbonate in a semipurified diet. All diets contained equivalent amounts of calcium. The occurrence of tibial dyschondroplasia was determined by visual scoring of the epiphyseal growth plate in the distal end of the tibiotarsus. None of the anions added to the diet at levels of 160 meq/kg or less affected body weight or feed consumption. A higher level of chloride (240 meq/kg) that was utilized in some experiments decreased weight gain by 16 to 22%. All anions except tribasic phosphate resulted in reduced blood pH or bicarbonate concentrations or both. Monobasic phosphate was more acidogenic than dibasic phosphate and sulfate and chloride was the most acidogenic of all mineral anions. All anions including tribasic phosphate increased the severity of tibial dyschondroplasia. There was no consistent relationship between blood pH, bicarbonate concentration, or partial pressure of CO2 and the severity of tibial dyschondroplasia.

Acid-Base Equilibrium↗

PubMed1992

Direct measurement of nitric oxide in headspace gas produced by a chicken macrophage cell line in a closed culture system.

A simple and rapid method was applied for direct measurement of nitric oxide (NO) gas produced by cultured macrophages using a modified chemiluminescence detector, the thermal energy analyzer (TEA). HD11 chicken macrophages (1-3 x 10(6)/ml) were cultured on microcarrier beads (100 mg/ml) in 140 ml air-tight glass jars (5 ml cell suspension per jar) containing 0.5 micrograms/ml of LPS and different concentrations of L-arginine. Headspace gas was sampled at 24 hours of culture via a rubber septum and directly injected into a TEA with a liquid nitrogen trap set at -130 to -140 degrees C. The concentration of NO in the gas sample was quantified using a standard gas mixture of NO (2 microliters/L) in nitrogen. Gas samples from L-arginine-supplemented cultures contained NO (0.028-0.066 pl/microliter), whereas NO was not detected in samples from controls. These results suggest that chicken macrophages synthesize NO gas in a dose-dependent manner relative to L-arginine concentration.

Animals↗

PubMed1992

Dietary arginine influences Rous sarcoma growth in a major histocompatibility B complex progressor genotype.

L-Arginine (L-Arg) can serve as a substrate for the production of reactive nitrogen intermediates. One of these metabolites, nitric oxide, has been shown to possess significant antitumor properties in vitro. To investigate the importance of this system in vivo, we have examined the dietary L-Arg host tumor interaction in the chicken. Since chickens are incapable of de novo L-Arg synthesis, concentration of this amino acid is readily controlled by diet. Line UNH 105 New Hampshire chickens having the major histocompatibility complex genotype, B24/B24, were used to study in vivo effects of dietary L-Arg on Rous sarcoma growth. After 5 weeks on a standard diet, 119 chicks were fed either a basal (0.92% L-Arg) diet or a high arginine (2.40% L-Arg) diet. One week later, chicks were wing-web inoculated with subgroup A Rous sarcoma virus. Tumor growth was monitored weekly for 12 weeks after inoculation. Plasma L-Arg levels and body weights from birds on each dietary treatment were analyzed. Neither body weight gains nor latent period for tumor development was affected by diet. However, plasma L-Arg levels were significantly different between dietary treatments (basal, 0.245 +/- 0.01 mumol/ml; high, 0.738 +/- 0.03 mumol/ml). In addition, mean tumor size scores were significantly (P less than 0.05) lower over time in chickens fed the high L-Arg diet. The results suggest that dietary L-Arg in excess of the amount required for growth reduces tumor load.

Animals↗

PubMed1991

L-arginine-dependent production of a reactive nitrogen intermediate by macrophages of a uricotelic species.

L-arginine-dependent production of reactive nitrogen intermediates (RNIs: nitric oxide, nitrite, and nitrate) by mammalian macrophages has been proposed to occur via an L-arginine oxidative deimination pathway and is known to be responsible for certain antineoplastic and antimicrobial effector functions. The present study represents the first examination of this pathway in a non-mammalian vertebrate. Because chickens, unlike mammals, lack a urea cycle and are incapable of de novo synthesis of L-arginine, the possible existence of an avian macrophage pathway for production of RNIs is questionable. We have defined conditions under which chicken macrophages are able to produce nitrite. Sephadex-elicited chicken peritoneal macrophages required a bacterial lipopolysaccharide (LPS from Escherichia coli) signal to produce nitrite during 24 hour cultures in the presence of L-arginine. As little as 5 ng/ml LPS resulted in significant nitrite production in culture. The relationship of nitrite production to both LPS and L-arginine levels was dose-dependent. D-arginine was unable to substitute for L-arginine but also produced no inhibitory effect. In contrast, L-NG-monomethyl arginine showed a significant inhibitory effect on nitrite production. A virus-transformed chicken macrophage cell line, HD11, also produced nitrite in a dose-dependent manner relative to both LPS and L-arginine concentration. Concentrations as low as 5 ng/ml LPS and 0.1 mM L-arginine resulted in significant nitrite production, while maximum levels of nitrite production were obtained using greater than or equal to 0.5 micrograms/ml LPS and greater than or equal to 0.4 mM L-arginine. These results indicate that chicken macrophages can produce RNIs. This production is dependent upon activation and is influenced by local L-arginine concentration. Moreover, because the chicken does not possess the ability to synthesize arginine and has an absolute nutritional requirement for this amino acid, the chicken represents a highly controllable system to examine the in vivo effects of L-arginine on macrophage-related immune functions.

Animals↗

PubMed1990

Effects of dietary minerals on acid-base balance and eggshell quality in chickens.

Three experiments were conducted in hens to determine the effects of high levels of dietary phosphorus (P, 1-1.5%), chloride (Cl, 0.8%) or both on acid-base balance and eggshell quality and to consider whether any adverse effects on eggshell quality can be attributed to alteration of blood acid-base balance. Eggshell quality and values for a blood indicator of acid-base balance were reduced by high levels of dietary P or Cl in all of the experiments. Eggshell quality and values for the blood acid-base indicator were further reduced by high dietary levels of the combination of minerals. The adverse effects associated with high levels of the combination were greater than the sum of adverse effects associated with high levels of each mineral. The effects of P and Cl on plasma levels of these minerals were inconsistent and varied among experiments. The use of pair-fed controls revealed that the adverse effects of combined P and Cl on eggshell quality and acid-base balance were independent of their effects on feed and calcium intake. Calcium excretion was increased by consumption of the high P, high Cl diet. The information obtained from these experiments suggests that the adverse effects of high levels of dietary P and/or Cl on eggshell quality may be due, at least in part, to increased Ca excretion. This, in turn, may be mediated by acidemia resulting from the dietary manipulations, although the present data were insufficient to provide a direct link between acidemia and Ca excretion.

Acid-Base Equilibrium↗

PubMed1989

Influence of dietary electrolytes on lysine and arginine absorption in chick intestine.

The intestinal absorption of lysine and arginine in the chick was characterized using an in situ-ligated intestinal segment technique, and the influence of dietary electrolytes on their absorption was examined. Each amino acid, labeled with 14C and provided at a concentration of .5 mM, was introduced into the lumen of the small intestine of young chicks. Absorption was defined as disappearance of label from the lumen after 4 min. Lysine absorption was greater than arginine absorption in the duodenum and in the middle and distal small intestine. The Jmax values for absorption of lysine and arginine were 315.0 nmol/min and 112.0 nmol/min, whereas the respective Kt values were 2.3 mM and 2.0 mM. Maximal transport of lysine and arginine occurred at pH 6.0. Lysine absorption was depressed (P less than .05) at pH 5.0 and pH 8.0, whereas arginine absorption was depressed (P less than .05) only at pH 8.0. High dietary chloride (.89%) produced higher (P less than .05) lysine absorption than a high dietary level of potassium (1.81%). No effect (P greater than .05) of dietary electrolytes on arginine absorption was detected. These results indicate that the dietary balance of monovalent electrolytes, and, hence, acid-base balance, may influence the intestinal absorption of lysine.

Analysis of Variance↗

PubMed1988

Interaction of dietary calcium and chloride and the influence of monovalent minerals on eggshell quality.

Two experiments were conducted to determine the influence of dietary sodium and chloride on eggshell quality of leghorn hens. In the first, hens were fed for 4 wk diets containing three levels of calcium (2.0, 2.8, and 3.5%) and two levels of chloride (.25 and .86%) in a factorial arrangement of treatments involving four replicates of five hens/treatment. Neither chloride nor calcium significantly affected hen-day egg production or egg weight (P greater than .05); however, chloride decreased feed consumption and calcium increased body weight gain (P less than .05). Interactions of calcium and chloride were significant for eggshell strength (P less than .06) and eggshell thickness (P less than .05). Chloride decreased these measures of eggshell quality only for hens receiving 2.0% calcium, and calcium improved both measures only for hens receiving .86% chloride. Chloride decreased blood bicarbonate concentration and base excess (P less than .05), but did not affect blood pH and pCO2 (P greater than .05). The effect of dietary sodium and chloride on eggshells of hens receiving 2.0% dietary calcium was determined in a second experiment. Seven diets ranging from .18% sodium and .94% chloride to .76% sodium and .24% chloride were provided for 4 wk to five replicates of five hens/treatment. Dietary sodium and chloride levels did not affect hen-day egg production or egg weight (P greater than .05). Increasing the proportions of sodium relative to chloride decreased food intake but increased eggshell strength and thickness (P less than .01) and increased blood pH (P less than .05), bicarbonate concentration (P less than .01), and base excess (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1987

Carrier-mediated transport of urate by chicken (Gallus domesticus) renal brush-border membrane vesicles.

1. Urate is transported by an anion exchange system in chicken renal brush-border membrane vesicles. An outward chloride gradient stimulates an overshoot in urate uptake. 2. The anion exchanger is similar to those described for the kidneys of rats and dogs except that the chicken exchanger has a higher specificity for urate. 3. p-Aminohippurate has only a weak affinity, if any, for the urate exchanger. 4. There were no apparent qualitative differences in urate transport between brush-border membrane vesicles from genetically normouricemic and hyperuricemic chickens.

Animals↗

PubMed1987

Urate and p-aminohippurate transport in isolated kidney tubules of normal and hyperuricemic chickens.

Urate and p-aminohippurate accumulations of kidney tubule fragments were studied in 5- to 6-week-old normal (LUA) and hyperuricemic (HUA) chickens. Tubules from LUA chicks consistently accumulated two to three-fold as much urate and p-aminohippurate as tubules from HUA chicks and thus confirmed the tubular origin of the urate transport defect in HUA chickens. A sodium gradient was required for optimal urate and p-aminohippurate accumulations and ouabain inhibited the accumulations of both compounds. Similar responses of urate and p-aminohippurate to treatments and reciprocal inhibitions between these compounds suggest that urate and p-aminohippurate are accumulated through a shared transport system.

Aminohippuric Acids↗

PubMed1987

Effect of dietary electrolyte balance on growth and acid-base status in swine.

The effect of dietary electrolyte balance on pigs fed lysine- or tryptophan-adequate or tryptophan-deficient diets was investigated in four experiments using 8- to 12-wk-old pigs. Electrolyte balance, expressed as Na+K-Cl in meq/kg of diet, was varied by altering dietary levels of Na and Cl while holding all other minerals constant. In two experiments in which the basal diet contained a balance of 135 meq/kg, simple lysine or tryptophan deficiences caused depressed growth, feed intake and efficiency of feed utilization, but none of these responses was altered by dietary supplementation with NaHCO3. In one experiment in which the electrolyte balance of the basal diet was 61 meq/kg and in which both lysine and tryptophan were limiting. NaHCO3 supplementation significantly increased growth and feed intake. This did not occur if the diet was also supplemented with tryptophan. A final experiment was conducted to determine the response of pigs to a range of electrolyte balance (-85 to 341 meq/kg) in a practical corn-soy diet containing adequate levels of all amino acids. Growth and feed intake appeared to be maximal for balances of 0 to 341 meq/kg Na+K-Cl, but were decreased at -85 meq/kg (P less than .05). Acid-base balance was adversely affected at 0 meq/kg. The results suggest that the response of lysine-deficient pigs to sodium bicarbonate is dependent upon the electrolyte balance of the diet, and also is influenced by other dietary amino acids.

Acid-Base Equilibrium↗

PubMed1987

Effect of dietary supplements of sodium or potassium bicarbonate on short-term macromineral balance in swine.

Four crossbred barrows, weighing an average of 26 kg each, were fitted with simple T-cannulas in the terminal ileum and placed in metabolism cages to evaluate the effect of dietary supplements of NaHCO3 or KHCO3 on the short-term metabolism of sodium (Na), potassium (K), calcium (Ca), magnesium (Mg) and chloride (Cl). A control diet containing 2.8 g/kg Na and 4.1 g/kg K was compared with similar diets supplemented with either 13 g/kg or 26 g/kg NaHCO3 or 30 g/kg KHCO3. All diets contained 4 g/kg Cr2O3 as an external marker and were offered twice daily (1,100 g X pig-1 X d-1) in a 4 X 4 Latin square arrangement. Feces and total urine output were collected for 24 h on the fifth day after introducing a new diet; digesta was collected for 12-h periods on d 6 and 7. Sodium and K concentrations at the terminal ileum were unaffected by dietary treatment. Apparent ileal digestibility of Na was increased by NaHCO3 supplements. Over the total gastrointestinal tract, diet had no affect on apparent Na digestibility. Urinary Na clearance was increased by NaHCO3 in the diet in a dose-dependent manner. Net Na retention (g/d) was increased by NaHCO3. Apparent ileal digestibility of K was increased by KHCO3. Apparent fecal digestibility of K was increased by KHCO3 and NaHCO3. Urinary K clearance was elevated by KHCO3, but not enough to overcome the increased K intake; net K balance (g/d) rose in response to dietary KHCO3 supplements. Sodium bicarbonate or KHCO3 had no effect on short-term digestibility or balance of Mg, Ca or Cl.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

Urea cycle activity and arginine formation in rainbow trout (Salmo gairdneri)

Studies were conducted to determine whether rainbow trout fingerlings possess the ability to synthesize arginine via the urea cycle. Several urea cycle enzymes were detected in trout tissues. An experiment was conducted to determine whether the enzymes increase in response to starvation or in response to dietary protein level (0, 30, 40, 50% protein). Although some effects were observed, they did not appear to be consistent with the function of the urea cycle as a mechanism of detoxifying ammonia in the fish. The activities of kidney arginase and liver and muscle carbamoyl phosphate synthetase (CPS) were higher (P less than 0.05) when protein was omitted from the diet (P less than 0.05) than when it was present but were unaffected by protein level otherwise. The activities of liver arginase and kidney and muscle CPS and ornithine transcarbamoylase (OTC) were higher (P less than 0.05) in starved fish than in fish that received adequate levels of protein. Liver CPS and OTC were lower in starved fish than in fish fed 30% protein. L-[l-14C]ornithine hydrochloride and L-[carbamoyl-14C]citrulline, injected intraperitoneally, were incorporated into tissue arginine, a finding consistent with arginine biosynthesis via the urea cycle. When one-half of dietary arginine was replaced by equimolar amounts of glutamic acid, ornithine or citrulline, glutamic acid markedly reduced growth (P less than 0.05), whereas growth was depressed only slightly by ornithine (P less than 0.05) and not depressed by citrulline (P greater than 0.05). We conclude that trout have a urea cycle that provides for potential arginine biosynthesis.

Animals↗

PubMed1986

Intestinal absorption of glucose and amino acids in chickens administered monensin.

Effects of the ionophoric anticoccidial agent monensin on glucose and amino acid absorption were investigated in young broiler chickens. Chicks housed in cages with wire floors were fed a practical diet containing 0 or 121 ppm monensin for 2 to 3 weeks prior to measurement of nutrient absorption. Chicks were anesthetized with halothane, and the intestine was accessed through an incision in the abdominal wall. A 10-cm segment of the intestine immediately anterior to Meckel's diverticulum was rinsed free of digesta and used for measurement of absorption in situ. One milliliter of saline solution containing 2 mM of glucose or a mixture of amino acids was injected into the lumen of the ligated segment, and recovery of glucose and amino acids in the lumen was determined after 4- and 5-min intervals, respectively. In one glucose study, the solution contained 0, 1, 10, or 80 micrograms/ml of monensin. In one amino acid study, the solution contained 0, 5, or 80 micrograms/ml of monensin; in subsequent studies, monensin was not included in the solution. Results show that neither dietary monensin nor monensin in the saline solution affected glucose absorption. Dietary monensin tended to depress lysine absorption but increased the absorption of tryptophan and arginine, the latter amino acid being markedly affected by monensin. Dietary monensin alone had no effect on absorption of cystine, isoleucine, methionine, or threonine. Inclusion of monensin in the saline solution depressed methionine absorption but only when birds also had been fed the diet containing monensin. Monensin in the saline solution depressed isoleucine absorption irrespective of dietary treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗