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Browsing by Author "Webb, Kenneth E. Jr."

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    An assessment of the effects of dietary oil supplementation on fetal survival in gilts at 40 days of gestation
    Rigau, Alberto Pérez (Virginia Tech, 1993-06-15)
    Eighty-six crossbred (Duroc x Yorkshire) gilts were used in two trials (50 gilts in Trial 1 and 36 gilts in Trial 2) for an assessment of the effect of supplemental dietary fat during early gestation on fetal survival, fetal development, and fatty acid concentration in gilt plasma and fetal head and body. Three diets contained 4% (w/w) added fat either as coconut, soybean, or fish (menhaden) oils. A fourth diet was used as a control. On d 37 to 45 postbreeding, gilts were slaughtered and numerous fetal and ovarian measurements made. Two sets of four randomly selected fetuses per gilt from Trial 1 were prepared. Blood samples from each gilt were obtained on the day of slaughter for determination of the plasma fatty acid profile. Across both trials, percentage fetal survival did not differ according to treatment, but in Trial 2 fetal survival was higher (P < .06) for gilts fed fish oil, compared with the controls. The fatty acid profile of plasma of gilts and the conceptus tissues were similar; both were influenced by the fatty acid concentration of the diets. The ratio of n-3/n-6 fatty acids was higher in conceptus tissue than in maternal plasma and the ratio was higher (P < .05) for the fish oil diet compared with the other diets. The relatively high concentration of omega-3 fatty acids in fetal tissues supports the hypothesis that omega-3 fatty acids play a role in the development of the pig conceptus and contributes to improve fetal survival. However, the high percentage fetal survival observed in all the treatments may have masked benefits of supplemental oil.
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    Availability of zinc from an amino acid chelate in Zn depleted pigs
    Swinkels, Johannes W. G. M. (Virginia Tech, 1992)
    This study was conducted to compare the availability of Zn from two Zn sources, an amino acid chelate and ZnSO₄. In three experiments, 78 Zn depleted and 24 Zn adequate pigs were used. Pigs were depleted of Zn by feeding an isolated soy protein, semi purified diet containing 17 ppm Zn. Of the 78 depleted pigs, 60 pigs were Zn repleted. During Zn repletion in Exp. 1, depleted pigs were fed the low Zn diet supplemented with 5, 15, or 45 ppm Zn either as ZnSO₄ or as Zn amino acid chelate (ZnAAC). In Exp. 2 and 3, low Zn diets were only supplemented with 45 ppm Zn. Zinc adequate pigs, used in Exp. 1 and 2, were fed the 45 ppm supplemental Zn diets. To evaluate differences in site and rate of apparent Zn absorption, chromic oxide was added to the diets of depleted pigs in Exp. 1 and 3. In all experiments, a 24-d period was sufficient to severely deplete the porcine body Zn stores, and to cause parakeratosis and growth retardation. Serum Zn concentrations and serum ALP-activities of depleted pigs dramatically decreased (P < .01) during the first 14 d of Zn depletion. At the end of Zn depletion, Zn contents in liver, kidney, pancreas, brain, and small intestine tissues of pigs fed the low Zn diet were reduced (P < .01) by 10 to 40 % compared with the adequate pigs fed the ZnSO₄ and ZnAAC diets. In Exp. 2, the growth retardation was associated with a low (P < .05) serum mitogenic activity and pituitary RNA content of depleted pigs compared with pair-fed adequate pigs. Moreover, the growth hormone mRNA fraction tended to be reduced (P < .10) for the Zn depleted pigs. In Exp. 1, the apparent absorption of Zn was higher (P < .01) for pigs fed ZnAAC compared with the ZnSO₄ group; however, this was not confirmed in Exp. 3 unless coefficients were corrected for Cr recovery. Furthermore, absorption of Zn occurred primarily within jejunal and distal segments of the small intestine. In the balance of Exp. 3, disappearance rates of Zn, Cu, Fe and DM were higher (P < .01) in depleted pigs fed ZnAAC compared with ZnSO₄. The recovery of Cr also was different (P < .01) between pigs fed the ZnSO₄ (87 %) and ZnAAC (70 %) diets. Moreover, the moisture content of the fecal matter was 11 % higher (P < .01) for the ZnAAC group compared with pigs fed ZnSO₄. In Exp. 1, depleted pigs fed the 15 ppm ZnSO₄ and ZnAAC diets regained their ability to grow, however, replenishment of body fluid and tissue Zn pools did not occur within the 24-d Zn repletion period. Both the 5 ppm ZnSO₄ and ZnAAC groups did not respond to Zn repletion within a 12-d period. In all experiments, the rate and degree of repletion of body fluid and tissue Zn stores was not different between pigs fed the 45 ppm ZnSOq and ZnAAC diets, although a higher (P < .05) serum mitogenic activity was observed for the adequate pigs fed ZnAAC compared with ZnSO4. In conclusion, an amino acid chelate did not improve growth, or rate and degree of replenishment of body fluid and tissue levels of Zn compared with pigs fed ZnSO₄. However, ZnAAC may have influenced intestinal luminal conditions since a higher rate of disappearance of Zn, Cu, Fe, Cr, and DM was measured.
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    Bioavailability of phosphorus from various sources for young turkeys
    Potchanakorn, Manop (Virginia Polytechnic Institute and State University, 1988)
    Three series of experiments were conducted to determine the relative bioavailability of various phosphate products with an emphasis on the defluorinated phosphates. In Series I, phosphorus in commercial mono/dicalcium phosphates, commercial dicalcium phosphates, commercial defluorinated phosphates, and experimental defluorinated phosphates were found to be 93, 81, 70, and 76% as available as that in dicalcium phosphate dihydrate, respectively, using 3-week bodyweight and toe ash in a nonlinear regression analysis. In Series II, phosphorus in a commercial defluorinated phosphate was compared directly with that in a commercial dicalcium phosphate using poult from 1 to 4 weeks of age. No significant differences were found between the two products which may be attributed partly to the feeding of the starter diet during the pre-experimental period. The commercial defluorinated phosphate was numerically less available than the commercial dicalcium phosphate in all cases. In Series III, phosphorus in various defluorinated phosphates was compared with that in a dicalcium phosphate dihydrate. Ash of dry unextracted tibia, ash of dry toe, and 0 to 3-week body weight gain as responses to added phosphorus followed a sigmoidal regression model while 0 to 2-week body weight gain followed an asymptotic model in Experiment 1. The defluorinated phosphate was found to be 53% as available as the standard. In Experiment 2, an experimental defluorinated phosphate from Series I which was found to be 76% as available as the standard was found to be 62% as available as the standard used in Series III, indicating differences in bioavailability of the two standards. In Experiment 3, two commercial defluorinated phosphates were found to have equal relative biological values, 67.2 and 67.6% as compared with the standard using poults from 0 to 2 weeks of age, and three experimental defluorinated phosphates 51.7, 74.0, and 88.2% with the product with the fine particles having the highest relative biological value. In cases where the sigmoidal regression gave a significantly better fit to the data than the asymptotic model, the relative biological values and the associated confidence limits from the asymptotic model were equal to those from the sigmoidal model.
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    Body composition of dogs determined by carcass composition analysis, deuterium oxide dilution, subjective and objective morphometry, and bioelectrical impedance
    Burkholder, William Joseph (Virginia Tech, 1994-05-16)
    Prediction of body composition was assessed in thirty-eight female and thirty-seven male random source dogs using in vivo methods of deuterium oxide dilution, subjective and objective morphometry, bioelectrical impedance and ultrasound, either separately or in various combinations. Carcass composition determined by chemical analyses of carcass homogenates served as criterion measures of body composition. Dogs were selected based on gender, body weight and body condition score. Body weight ranged from 7.3 to 34.5 kilograms (kg), subdivided into 4.5 kg increments with 6 female and 6 male dogs per increment. Body condition was categorized as thin, optimum or obese using a defined criteria, body condition scoring system (subjective morphometry) with 12 female and 12 male dogs per body condition category. Selection criteria produced 18 body weight condition groups with 2 female and 2 male dogs per group. One additional male and 2 female dogs were included for economic and ethical reasons. Equations to predict carcass composition from in vivo measurements were derived using standard regression techniques. Influence diagnostics, residual analysis and data splitting were used to validate predictive equations. Predictions from deuterium oxide dilution produced the most precise estimates of body composition. Average standard errors of estimation (SEE) from deuterium equations were 1.3, 1.8, 1.0, and 0.4 percent for percentages of body moisture, fat, protein and ash, respectively, and 0.39, 0.57,0.21 and 0.08 kg for absolute quantities of moisture, fat, protein and ash, respectively. Morphometry produced the most imprecise, but economical, estimates. Average SEE from morphometry equations for proportions were 3.0, 4.0, 1.3, and 0.4 percent, and 0.9, 0.9, 0.3 and 0.07 kg for absolute quantities of moisture, fat, protein and ash, respectively. Subjective morphometry could estimate body fat with an average SEE of 3.4 percent and correctly categorized 75 percent of the dogs. Bioelectrical impedance and ultrasound produced predictions with average SEE intermediate to deuterium and morphometry. Bioelectrical impedance was equivalent to deuterium dilution on the basis of cost per unit improvement in SEE, but ultrasound was not cost effective.
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    Broiler Performance and Intestinal Alterations When Fed Drug-Free Diets
    Sun, Xiaolun (Virginia Tech, 2004-08-10)
    A study was carried out to investigate the effects of a drug-free feeding program on broiler performances. A total of 2,496 Cobb 500 chicks were randomly assigned to one of four dietary treatments with each group replicated 13 times. The four diets evaluated were: 1) negative control (NC): basal diet without growth promoter or coccidiostat; 2) positive control (PC): diet 1 + Lincomycin; 3) Program 1 (PG1): diet 1 + Bio-Mos®, Vegpro®, MTB-100®, Acid Pak 4-Way®, and All-Lac XCL®; 4) Program 2 (PG2): diet 1 + Bio-Mos® and All-Lac XCL®. Additives were used at commercially recommended rates. All chicks were vaccinated with a live oocyst coccidia vaccine on d 0 at the hatchery. Four phases of feeding were used during the trial with changes occurring at d 14, 28, and 35. Performance values measured were body weight, feed intake, yield, and mortality, while body weight gain and feed conversation rate (FCR) were calculated. Chicks were challenged with coccidia at d 14 to evaluate the protective effect of the feeding programs and coccidia vaccination. Segments of duodenum, ileum, and ceca were removed to measure intestinal morphology. Final body weight gains of birds on PC (2.736 kg) were greater (P < 0.05) compared to NC (2.650 kg), while birds on PG1 (2.681 kg) and PG2 (2.710 kg) were similar to positive and negative control. Overall, feed intake was similar across the treatments with the exception of period 2 (15 to 28 days) when birds consumed more (P < 0.05) of PC and PG1 compared to NC. Cumulative FCR at d 35 and 49 was improved (P < 0.05) in birds consuming PC and PG2 when compared to NC. Overall, birds consuming NC had greater mortality (P < 0.05; 12%) compared to PC (7.6 %), PG1 (4.6%) and PG2 (6.7 %) with most of the mortality occurring from d 0 to d 28. Mortality for birds consuming PG1 was also lower (P < 0.05) compared to the PC. There were no dietary effects on lesion scores or yields of processed products at d 42 (females) or d 49 (males). Interaction of dietary treatments with age and days of age alone showed effects (P < 0.0001) on the morphology of duodenum, ileum, and ceca. Lamina propria in ceca was thicker (P < 0.008) in birds consuming NC compared to PG1 and PG2. This study indicated that feeding birds without growth promoters resulted in greater mortality and decreased performance compared to using an antibiotic, while Bio-Mos® in combination with All-Lac XCL® helped to reduce the negative effects.
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    Carbohydrate Supplementation and Resistance Exercise Performance in Males Undergoing Energy Restriction
    Dalton, Renee A. III (Virginia Tech, 1997-07-25)
    This study examined the effects of carbohydrate supplementation on resistance exercise performance, cortisol levels, and creatine kinase levels in trained males undergoing energy restriction. Sixteen experimental subjects were randomly assigned to a carbohydrate (C, n=8) or placebo group (P, n=8). The remaining six subjects served as controls (N). Performance tests were done before (Trials 1 and 2) and after (Trial 3) energy restriction. Experimental subjects consumed a low calorie formula diet for three days (18 kcal-1 kg-1 d-1). They had blood drawn before and after T2 and T3. For T3, they consumed either a carbohydrate (1g kg-1) or a placebo beverage 30 minutes before exercise. There was a significant increase in resting cortisol levels following energy restriction. CK levels were significantly elevated after exercise, suggestion muscle damage. Carbohydrate supplementation had no effect on blood glucose, cortisol, creatine kinase, or RPE. The number of repetitions performed during the final set of bench press showed significant interaction between groups and time. P and N increased the number of repetitions performed from T2 to T3 (15.0 + 1.4 to 17.3 + 0.8 for P, 15.0 + 2.7 to 16.7 + 2.3 for N). C decreased the number of repetitions performed 17.6 + 0.7 to 17.3 + 1.0). The number of repetitions performed during the final set of leg extensions showed no interaction between groups and time (p=0.801). This study did not support a benefit of consuming carbohydrate prior to resistance exercise for dieting athletes but illustrates that energy restriction increases a catabolic hormone.
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    Central control of food intake in the domestic fowl
    Skewes, Peter Alan (Virginia Polytechnic Institute and State University, 1985)
    This study was initiated to determine if factors exist in the blood or cerebrospinal fluid (CSF) of the domestic fowl that act upon the central nervous system to control food intake. Plasma collected from free-feeding and 24-hour fasted leghorn cockerels was lyophilized, reconstituted to 2, 4, or 5 times the original concentration, and injected, via a stereotaxically implanted 23 gauge stainless steel guide cannula, into the lateral ventricle of free-feeding leghorn cockerels. Food intake was significantly reduced following injection of 2, 4, and 5 times normal concentration of plasma from free-feeding birds. Plasma from fasted birds did not alter food intake regardless of concentration, but did significantly reduce water intake when concentrated to five times normal. A similar study was conducted with fractions of plasma of different molecular weight ranges. Plasma collected from free-feeding cockerels was partitioned by gel filtration into the following molecular weight fractions: >5000 molecular weight, <5000 molecular weight, 1500-5000 molecular weight, and <1500 molecular weight. The fractions were lyophilized and reconstituted to four times the original concentration and injected into the lateral ventricle of free-feeding leghorn cockerels. Food intake was significantly decreased by the <5000 and <1500 molecular weight fractions, whereas water intake was not affected. The 1500-5000 molecular weight fraction and the fraction above 5000 did not affect food or water intake. To determine if this food intake inhibiting factor existed in the cerebrospinal fluid (CSF) of the domestic fowl, CSF was collected from free-feeding and 24-hour fasted broilers and injected into the lateral ventricle of leghorn and broiler cockerels. Food intake was not affected by either the normal or four-times normal concentration of CSF collected from free-feeding or 24-hour fasted broilers. Water intake was significantly increased in the leghorn and broiler birds receiving the four times normal concentration of CSF collected from 24-hour fasted birds, but was not affected in the birds receiving CSF collected from the free-feeding donors. It appears, therefore, that a food intake inhibiting factor exists in the plasma of the free-feeding domestic fowl that does not exist in the CSF.
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    Characterization of estrogen and glucocorticoid receptors, skeletal muscle protein turnover and tissue growth in lambs treated with trenbolone acetate and estradiol
    Frey, Randall Scott (Virginia Tech, 1988-02-15)
    A study was conducted to determine the effects of trenbolone acetate (TBA) and estradiol-17B (E2) implantation on the characteristics of the glucocorticoid and E2 receptor, skeletal muscle protein turnover and tissue growth. Twenty-four lambs were utilized. Trenbolone acetate did not ,affect (P>.10) degradation rates in the semitendinosus (ST) and triceps brachii (TB) muscles, the production of cortisol, adrenal weights and cytosolic glucocorticoid binding capacity (Bmax). Trenbolone acetate decreased synthesis rate of muscle protein (P<.Ol), the percent of [3H] dexamethasone binding in the nuclear fraction, Bmax and the disociation constant (Kd) of the cytosolic E2 receptor, only in the TB muscle. Deoxyribonucleic acid (DNA) of the TB was increased (P<.05) with TBA. Pituitary weights were decreased (P<.005) with TBA and increased (P<.Ol) with E2. Estradiol decreased (P<.05) Bmax of the cytosolic E2 receptor in the ST and decreased (P<.05) Bmax of the nuclear E2 receptor in the TB muscle. The TB muscle had greater (P<.05) synthesis rates than the ST and the protein:RNA ratio was decreased (P<.05) in the TB. The TB muscle had greater (P<.005) Bmax for the cytosolic glucocorticoid receptor.
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    Characterization of Glycyl-Sarcosine Uptake by Ovine Intestinal Brush Border Membrane Vesicles
    Bowers, Sharon H. (Virginia Tech, 1997-08-19)
    In order to characterize peptide transport in the ovine small intestine, [14C]-glycyl-sarcosine uptake by tissue collected from five sheep was studied through the use of brush border membrane vesicles (BBMV). Preliminary experiments determined that incubation in hyaluronidase is not necessary in order to separate mucosal tissue from the basement membrane and that the stop solution used in the uptake study needed to be buffered. Uptake was examined in proximal (denoted jejunal) and distal (denoted ileal) halves of the intestine at four times (15, 30, 45, and 60 s) and at three extravesicular pH levels (6.4, 7.0, and 7.5). An intravesicular pH of 7.5 was used throughout the study. The two tissue sites differed (P < .02), with BBMV from jejunal tissue showing greater uptake than ileal. Uptake plateaued after 45 s, resulting in a quadratic (P < .005) effect of time. The effect of changes in extravesicular pH was also quadratic (P < .04), with uptake being greatest at pH 6.4, lowest at pH 7.0 and intermediate between the two at pH 7.5. Peptide uptake by sheep jejunal and ileal BBMV was demonstrated, but there was no clear evidence for increased uptake with decreasing extravesicular pH.
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    Cloning, Expression, and Developmental and Dietary Regulations of a Chicken Intestinal Peptide Transporter and Characterization and Regulation of an Ovine Gastrointestinal Peptide Transporter Expressed in a Mammalian Cell Line
    Chen, Hong (Virginia Tech, 2001-09-28)
    To study peptide absorption in chickens, an intestinal peptide transporter cDNA (cPepT1) was isolated from a chicken cDNA library. The cDNA was 2,914-bp and encoded a protein of 714 amino acid residues. Twenty-three di-, tri-, and tetra-peptides were used for functional analysis of cPepT1 in Xenopus oocytes and Chinese hamster ovary (CHO) cells. For most di- and tripeptides tested, the Kt was in the micromolar range, except Lys-Lys and Lys-Trp-Lys. Northern analysis demonstrated that cPepT1 is expressed strongly in the small intestine, and at lower levels in kidney and cecum. These results demonstrated the presence and functions of a peptide transporter in chickens. cPepT1 mRNA abundance was evaluated in response to developmental and dietary regulations. In Experiment 1, eggs at incubation day 18 (E18) and Cobb chicks after hatch (d 0) were sampled before treatments. Three groups of chicks were fed diets containing 12, 18, or 24% crude protein (CP). Feed intake of chicks fed the 18 or 24% CP diets was restricted to that of chicks fed the 12% CP diet. In Experiment 2, a fourth group with free access to the 24% CP diet was added. cPepT1 mRNA abundance was quantified from northern blots. By d 0, there was a 50-fold increase in cPepT1 mRNA abundance compared with E 18. In chicks fed the 12% CP diet, cPepT1 mRNA abundance decreased throughout the 35 d. Chicks fed 18 or 24% CP diets showed an increase in cPepT1 mRNA abundance with time. In chicks with free access to the 24% CP diet, cPepT1 mRNA decreased until d 14 but returned to an intermediate level at d 35. Our results indicate that cPepT1 mRNA is regulated by both dietary protein and developmental stage. To investigate the kinetics of an ovine peptide transporter (oPepT1), CHO cells were transfected with oPepT1 cDNA. Uptake of Gly-Sar by transfected cells was pH-dependent, concentration-dependent, and saturable. Competition studies showed that all di-, tri-, and tetra-peptides inhibited uptake of Gly-Sar. Pretreatment of the cells with staurosporine resulted in an increase in peptide transport. This increase was blocked by pretreatment with PMA. The results indicate that protein kinase plays a role in oPepT1 function.
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    Cloning, Sequencing and Expression of a Porcine Intestinal Peptide Transporter in a Mammalian Cell Line
    Klang, Judith Elisa (Virginia Tech, 2002-12-10)
    Absorption of dietary proteins can be met through the uptake of free amino acids or as small peptides. A peptide transport protein, PepT1, is responsible for the absorption of intact peptides arising from digestion of dietary proteins. PepT1 is driven by a H+-coupled transport system that allows for the absorption of small peptides through the intestinal brush border membrane. Screening of a porcine intestinal cDNA library with a sheep PepT1 cDNA probe resulted in the identification of three porcine PepT1 (pPepT1) cDNAs of varying sizes and sequences. Each variant cDNA isolated was cloned into a mammalian expression vector, sequenced, and expressed in Chinese hamster ovary (CHO) cells. Peptide transport was assessed by uptake studies using the radiolabeled dipeptide [3H]-Gly-Sar. Only one of the three cDNAs encoding for a protein of 708 amino acids induced H+-dependent peptide transport activity. Through computer analysis, a putative protein structure for pPepT1 was developed. The transporter has an unusual 13 transmembrane structure with the N-terminus located extracellularly and the C-terminus located intracellularly. Seven glycosylation sites and three protein kinase C phosphorylation sites are located throughout the protein. Expression of pPepT1 activity in CHO cells had a optimal peptide uptake at 18-24 hours. The transporter showed optimal uptake at a pH of 5.5-6.0. Eighteen different unlabeled dipeptides and tripeptides were found to inhibit the uptake of [3H] -Gly-Sar in competition studies. The IC50 of 13 of the dipeptides and two tripeptides ranged between 0.015 to 0.4 mmol/L. The exceptions were Lys-Lys, Arg-Lys, and Lys-Trp-Lys, which showed IC50 values greater than 1.37 mmol/L and appear to be poor substrates for pPepT1. All three of the tetrapeptides examined showed very high IC50 values and inhibition of the uptake of Gly-Sar was too small to measure even at a 10mM concentration. Dipeptides and tripeptides appear to be substrates for the porcine intestinal peptide transporter while tetrapeptides do not appear to be transported.
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    Composition and in vivo and in vitro digestibility of cattle fecal waste
    Lucas, Donald Montgomery (Virginia Tech, 1974-04-05)
    Three digestion trials were conducted with six yearling steers to study apparent digestibility of fecal waste from steers fed a ground, high roughage finishing ration. In the first trial steers were fed a basal ration containing approximately 50% roughage. The ration contained 14.3% crude protein and 22.8% crude fiber, dry basis. Apparent digestibility was 65% for dry matter and 66% for crude protein. The feces collected during this trial were dried in a forced air oven at 120 C and ground. The chemical composition of the feces was 13.2% crude protein, 31.4% crude fiber, 2.8% ether extract, 5.4% ash, 38.8% NFE, 70.9% cell walls and 44.8% ADF, dry basis. For trials 2 and 3 a switch-back design was used. In each trial one-half of the steers were fed the basal and the remainder were fed a ration in which dried cattle feces collected during trial 1 were substituted for 20% of the basal ration.
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    Compositions and methods for the treatment of dietary deficiencies
    (United States Patent and Trademark Office, 1992-12-01)
    Compositions containing peptides which are capable of absorption in the stomach are supplied to animals, such as but not limited to ruminants, in order to supply nutrients and treat dietary deficiencies. In a preferred embodiment, peptides containing at least one other amino acid which animals are deficient in are supplied to animals to treat specific amino acids deficiencies. Preferably, the peptides contain glycine, phenylalanine, or proline, and the peptides are formed from a total of four or less amino acid residues. An alternative embodiment involves formulation of peptide derivatives through the attachment of mineral compounds or medicaments to peptides, and the peptide derivatives are then supplied to the diet to treat mineral deficiencies or illnesses. The compositions and methods are particularly useful in treating amino acid deficiencies, such as but not limited to methionine deficiencies in ruminants.
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    Contaminants at a Shooting Range: Toxicological and Nutritional Significance to Birds and Mammals
    Gonzalez, Gabriela Rae (Virginia Tech, 2003-08-08)
    Target shooting in the United States has become an increasingly popular sport in the last century. In addition to the large quantity of lead pellets littering range grounds and surrounding land, considerable amounts of clay target fragments cover shooting range areas as well as adjoining habitats. Polycyclic aromatic hydrocarbons (PAHs) within the target, as well as lead pellets from shotguns pose multiple threats to a variety of wildlife. To determine the effects of clay target and lead pellet ingestion on wildlife, I conducted controlled experiments on Coturnix quail exposed to clay targets in the lab, and collected wild birds and mammals exposed to lead pellets at a shooting range. The first Coturnix study determined whether quail voluntarily consumed target fragments or limestone fragments. In both fall (F=29.2, P<0.01) and spring (F=6.45, P=0.02) experiments, I found that quail consistently selected limestone fragments, but almost completely rejected clay target fragments. In the second study, quail were force-fed varying amounts of target dust on a weekly basis to simulate sporadic exposure to clay target dust. In both summer (F=1.63, P=0.23) and winter (F=0.34, P=0.8) trials, male quail did not have significant weight loss. Female quail had insignificant weight losses in summer trials (F=1.63, P=0.23) but experienced weight gains in winter trials (F=3.53, P=0.04). In the third and final Coturnix study, varying amounts of target dust were incorporated into daily feed rations to simulate frequent exposure to clay target dust. Male quail experienced weight loss in both summer (F=16.13, P<0.01) and winter (F=8.47, P<0.01) trials. Female quail also suffered weight loss in both summer (F=15.62, P<0.01) and winter (F=17.50, P<0.01) trials. Weight loss likely resulted from inadequate nutrition as opposed to target poisoning. However, because there were no biochemical analyses performed to test for PAH presence, no definite conclusions can be made. The second study focused on lead contamination in Passeriformes, perching birds, and small mammals. Seventeen of 20 birds (85%) (Passerine spp) captured at the shooting range had elevated lead levels (F=5.21, P<0.028), when compared to birds (n=20) at the control site. Nine of 26 (35%) white-footed mice (Peromyscous leucopus), trapped at the shooting range had elevated liver (F=9.78, P=0.0029) and kidney (F=22.49, P<0.01) lead levels. These results indicate that Passerine species as well as Peromyscous species around shooting ranges inadvertently consume lead, either as lead pellets, mistaking them for grit or dietary items, or through environmental sources such as water, soil, and vegetation.
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    Cytokine mRNA Expression in the Small Intestine of Weanling Pigs Fed Diets Supplemented with Specialized Protein or Peptide Sources
    Zhao, J.; Harper, Allen F.; Webb, Kenneth E. Jr.; Kuehn, Larry Alexander; Gilbert, Elizabeth R.; Xiao, X.; Wong, Eric A. (2008-12)
    Cytokines play a central role in the mucosal immune response and are involved in regulation of nutrient absorption, metabolism and animal growth This study investigated the effect of diet manipulation with specialized protein or peptide sources on expression of cytokine (IL-1, IL-6, IL-10, and TNF-alpha) mRNA abundance in different intestinal regions and at different ages post-weaning in piglets. A total of 48 (17 days of age, 6.16 +/- 0.34 kg BW) weanling pigs were fed either a corn-soy/whey protein basal diet, the basal diet supplemented with spray-dried plasma protein (SDPP), or the basal diet supplemented with Peptiva (R), a hydrolyzed marine plant protein. A fourth treatment group was fed the SDPP diet, but the feed intake level was limited (SDPP-LF). Pigs were killed at 3 and 10 d, and intestinal cytokine mRNA was measured by real-time PCR using the relative quantification method. The SDPP-LF group exhibited an increased TNF-alpha mRNA abundance compared with the ad libitum SDPP group (p<0.05). The TNF-alpha and IL-10 mRNA abundance increased from the proximal to distal part of the intestine, and the mRNA abundance was greater (p<0.01) in the distal intestine as compared with the proximal and middle intestine. The cytokines IL-1-beta, IL-10 and TNF-alpha mRNA abundance also increased from d3 to d10 postweaning (p<0.01). In summary, restricted feeding increased the TNF-alpha mRNA abundance in the small intestine, however neither SDPP nor peptide supplementation affected cytokine mRNA expression. Abundance of mRNA for most cytokines examined in this study increased with age post-weaning, suggesting that during 10 d after weaning the mucosal immune system is still under development.
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    Defining effective fiber content of dairy rations
    Maddox, Terry L. (Virginia Polytechnic Institute and State University, 1982)
    Cottonseed hulls (CSH), chopped orchardgrass (OG) or alfalfa (ALF) hays were added to corn silage-based rations to determine effects on dry matter intake (DMI), nitrogen balance (NB), rumen volatile fatty acids (VFA), and rumen fluid (RFD) and solids (RSD) dilution rates. DMI was highest for added fiber rations and higher for CSH than hay rations. Digestibility of DM was depressed for added fiber rations with lowest for CSH. Most favorable NB was for CSH rations. Rumen VFA were not altered by fiber additions. Highest RFD was for 0% rations and lowest for 9% rations, however CSH had greatest positive influence on RFD. RSD trend was similar to that for RFD. In Experiment II, 4 corn silage-based rations containing 9% OG, ALF, or CSH plus a Control (9% OG) were compared for effect on DMI, rumen VFA, chewing time (CT), RSD, and RFD. Ration density decreased with OG and ALF whereas CSH had no effect compared to Control. DMI was higher for CSH compared to OG and ALF. Total CT (min/d) and Roughage Value Index (CT/kg DMI) were reduced for ALF compared to OG. Total VFA were lower for added fiber rations compared to Control. Acetate:propionate (APR) and non-glucogenic (NGR) ratio were not affected by fiber additions. RFD was reduced for ALF compared to OG whereas CSH was higher than OG and ALF. Reduced RFD was associated with reduced total CT for ALF. RSD was not affected by fiber additions. Chopped OG was supplemented at 0, 9, or 18% of ration DM in a finely chopped corn silage-based ration. Analysis of covariance was performed using 18 lactating Holsteins. Ration density decreased with each increment of OG. DMI was highest for 18% OG ration. Cows on 0% showed decreased DMI whereas cows on 9 and 18% rations increased DMI from covariate period. Rumen acetate, APR and NGR increased while propionate and total VFA decreased with increasing OG. RFD and RSD increased with increasing OG supplementation. Response to 9 and 18% supplementation of OG, ALF, or CSH to corn silage-based rations appears to follow similar pattern as when all-forage rations were compared to all-concentrate rations for lactating dairy cows. A more quantitative evaluation of physical form is needed for dairy rations and feedstuffs leading to an acceptable routine evaluation procedure.
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    Demonstration of peptide and free amino acid absorption by sheep forestomach epithelium using parabiotic chambers and identification of H⁺/peptide and free amino acid transport proteins in sheep omasal epithelium and bo,+ amino acid transport proteins in pig jejunal epithelium by expression of mRNA in Xenopus laevis oocytes
    Matthews, James Clyde (Virginia Tech, 1995-04-12)
    The absorption of methionine and methionylglycine (Met-Gly) across sheep (average BW = 38 kg) ruminal and omasal epithelia was studied using parabiotic chambers. Ruminal tissue demonstrated a greater ability to accumulate both substrates. Omasal tissue demonstrated a greater ability to translocate methionine and Met-Gly and a greater total absorption of both. Intact Met-Gly was transferred across both tissues. More was hydrolyzed by omasal epithelia. Within tissues, the total absorption of substrates did not differ. Evidence for carrier-mediated absorption was not observed. The ability to express exogenous mRNA in defolliculated Xenopus laevis oocytes was developed using sucrose gradient size-fractionated poly(A)⁺ RNA (RNA) isolated from the jejunal epithelial tissue of pig (average BW = 33.8 kg). Compared to water-injected oocytes, RNA injected oocytes displayed greater rates of Nat-independent lysine and leucine absorption. RNA-induced uptake of lysine (Kt = 52 uM) and leucine (Kt = 97 uM) was inhibited by 5 mM leucine and lysine, respectively, by .2 mM cysteine, but not by 5 mM glutamate. RNA-induced lysine and leucine absorption also was inhibited when oocytes were injected with RNA plus DNA oligomers that were complementary to the cloned human kidney b⁰‘⁺ transporter. Oocytes were injected with RNA isolated from omasal epithelial tissue of sheep (average BW = 67.5 kg) to identify potential peptide and amino acid transport proteins. Injection of specific RNA fractions induced greater rates of glycylsarcosine (Gly-Sar) uptake, as compared to water injection of oocytes. Media pH of less than 6.5 was required for induced Gly-Sar uptake. Induced Gly-Sar uptake required a pH of less than 6.5, was saturable (Kt = .40 mM), and was inhibited by 5 mM carnosine, Met-Gly, glycylleucine, but not by glycine. The RNA-induced Gly-Sar absorption was completely inhibited when oocytes were co-injected with RNA and DNA oligomers that were complementary to the cloned rabbit H⁺/peptide cotransporter. When oocytes were assayed for their ability to absorb lysine, RNA-induced lysine absorption was determined to be Na⁺-independent and to display b⁰‘⁺-like transport activity. Collectively, these results indicate that sheep omasal epithelia possess the potential to absorb free and peptide-bound amino acids by non-mediated processes and possess mRNA that encode for Ht-dependent dipeptide and b⁰‘⁺ transport protein activity. mRNA that encodes for b⁰‘⁺-like transport activity was identified in the jejunal epithelium of growing pigs.
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    Determination of vitamin B-6, available lysine and pyridoxyllysine in a new instant baby food product
    Grün, Ingolf (Virginia Tech, 1989-06-02)
    The purpose of this study was to compare the nutrient content of a new instant baby food product to jar baby food of similar product formulation. Instant and jar "Vegetable and Beef" and "Bananas" products processed in 1985 and 1987 were analyzed for available lysine, vitamin B-6 and pyridoxyllysine content. The available lysine content of 100 grams of baby food was found to be higher in the instant products, but when adjusted for protein content, available lysine was higher in the jar products. This indicates that drum-drying used for the instant products is more detrimental in regard to lysine availability than retorting. The vitamin B-6 content of the instant products was found to be higher than that of the jar products. However, due to the addition of ingredients with little or no vitamin B-6 content to the jar products, no conclusion about processing effects on vitamin B-6 content can be made. Products processed in 1985 tended to be lower in nutrient content than the products processed in 1987. Pyridoxyllysine, a compound thought to affect vitamin B-6 bioavailability, could not be detected in any of the baby foods, either by amino acid or HPLC analysis. The instant products were found to be at least equal to the jar products with regard to available lysine and vitamin B-6 content. All products also appear to provide sufficient amounts of these nutrients to infants less than one year of age.
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    Developmental Gene Expression in the Small Intestine of Chickens from Lines Divergently Selected for High or Low Juvenile Body Weight
    Miller, Carin R. (Virginia Tech, 2007-09-10)
    Nutrient transporters in the small intestine are responsible for dietary nutrient assimilation and therefore the expression of these transporters can influence the overall nutrient status as well as the growth and development of the animal. This thesis examined correlated responses to selection in the developmental gene expression of the peptide transporter PepT1, the glutamate/aspartate transporter EAAT3, the sodium-dependent glucose transporter SGLT1, and the fructose transporter GLUT5 in the small intestine of chickens from lines divergently selected for high (HH) or low (LL) eight-week body weight and their reciprocal crosses, (HL and LH). Chicks were weighed and killed on embryonic day 20 (E20), day of hatch (DOH with no access to feed), and days 3 (D3), 7(D7), and 14 (D14) post hatch. Duodenum, jejunum, ileum and liver were collected. DNA extracted from liver was used to sex birds by PCR. RNA was extracted from the intestinal segments of four males and four females from each mating combination (MC) and time point except E20 HL males (n = 3) and D7 LL females (n = 2). Expression of nutrient transporters was assayed by real-time PCR using the relative quantification method. In comparing HH and LL males and females there was a line by segment interaction in PepT1 gene expression, with no segment difference in HH and greatest expression in the ileum of the LL (P < 0.05). There was also a MC by age by sex interaction for PepT1 gene expression (P < 0.0001) with peak gene expression occurring on DOH for LL females, on D7 for HH females, on D7 for LL males and D14 for HH males. Overall, females had greater EAAT3 expression (P < 0.03). Gene expression of EAAT3 was greatest in the ileum, intermediate in the jejunum, and least in the duodenum (P < 0.0007). There was an age by segment interaction for EAAT3 expression (P = 0.0002) and a MC by segment interaction (P < 0.02), with LL having greater expression than HH in the ileum. Females had greater SGLT1 expression than males (P < 0.0001). There was a sex by age interaction for the expression of SGLT1 (P < 0.0001). Females induced SGLT1 expression on DOH and maintained this level through D14, while males gradually increased expression through D7 and decreased expression by D14. These results indicate that expression of PepT1, EAAT3, SGLT1 are differentially expressed in male and female chickens regardless of selection for high or low juvenile body weight. These results also show a sexual dimorphism in the capacity to absorb peptides, anionic amino acids, and glucose from the intestine, which has implications for the poultry industry with regard to diet formulations for straight-run and sex-separate grow-out operations. In comparing male HH, HL, LH, and LL chicks, overall LL had the greatest level of expression (P <0.06), HH had the least level of expression (P < 0.006) and HL and LH had intermediate levels of expression (P < 0.06). Greatest PepT1 gene was expression in the ileum (P < 0.0003) and there was a MC by segment interaction with expression increasing from duodenum to ileum in LL, but there was no segment difference in any other MC (P < 0.08). Within each intestinal segment there was a MC difference (P < 0.02). There was an effect of sire for PepT1 expression, with progeny from low weight selected sires (LWS) having greater expression than progeny from high weight selected (HWS) sires (P = 0.0008). There was no difference between intestinal segments in progeny from HWS sires, however, greatest PepT1 gene expression was seen in the ileum of progeny from LWS sires (P < 0.0001). Overall, expression of EAAT3 was greatest in the ileum, intermediate in the jejunum and least in the ileum (P < 0.0001) and there was a segment by age interaction for EAAT3 expression (P < 0.0001). In all MCs except HH, EAAT3 gene expression increased from duodenum to ileum (P < 0.08). Within the ileum, the LL had greatest EAAT3 gene expression, LH and HL had intermediate gene expression, and HH had least expression (P < 0.08). Expression of SGLT1 gradually increased through D7 and decreased by D14 (P < 0.0001) and overall, was greatest in the distal small intestine (P < 0.0001). There was a MC by segment interaction, with SGLT1 gene expression being greatest in the distal small intestine in LL, LH, and HL, but greatest in the jejunum of HH (P < 0.04). Within the ileum, LL had greater SGLT1 gene expression than HH (P < 0.06). Overall, greatest GLUT5 expression was in the distal small intestine (P < 0.0001) and there was a MC by segment interaction, with expression being greatest in the distal small intestine in LL and HL (P < 0.02), greatest in the ileum of LH (P < 0.08), and greatest in the jejunum of HH (P < 0.09). Within the ileum there was a MC difference (P < 0.07). These results indicate that selection for high or low juvenile body weight may have influenced the gene expression pattern of these nutrient transporters in the small intestine, which may contribute to the overall differences in the growth and development of these lines of chickens.
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    Developmental Regulation of the Expression of Nutrient Transporter and BrushBorder Membrane Hydrolase Genes in the Small Intestine of Piglets
    Xiao, Xunjun (Virginia Tech, 2005-12-14)
    The objective of this study was to evaluate developmental regulation of the expression of nutrient transporter and brushborder hydrolase genes in the small intestine of piglets. Seventy piglets from seven sows were killed at birth (d 0), during suckling (d 1, 3, 7, 14, 21) and postweaning (d 22, 24, 28, 35), and intestinal segments (duodenum, jejunum and ileum) were collected. The mRNA abundance was determined by Northern blot using specific cDNA probes for three disaccharidases (lactase-phlorizin hydrolase, LPH, sucrase-isomaltase, SI, and maltase-glucoamylase, MGA), three peptide hydrolases (aminopeptidase A, APA, aminopeptidase N, APN, and dipeptidyl peptidase IV, DPP IV), two sugar transporters (Na+-dependent glucose transporter 1, SGLT1, and facilitated glucose transporter 5, GLUT5), a peptide transporter (H+-dependent peptide transporter 1, PepT1), four amino acid transporters (excitatory amino acid carrier 1, EAAC1, Na+-dependent neutral amino acid transporter, ATB0, the light chain of a heterodimeric transport system b0,+ involved in the heteroexchange of cationic and neutral amino acids, b0,+AT, and Na+-independent large branched and aromatic neutral amino acid transporter 2, LAT2), and two iron transporters (divalent metal ion transporter 1, DMT1, and iron-regulated transporter 1, IREG1). Protein expression was quantified by Western blot using specific antibodies for LPH, SI, SGLT1, and PepT1. During suckling, the abundance of LPH, APA, APN, DPP IV, b0,+AT mRNA increased quadratically (P < 0.001) with age from birth to d 7 or 14 then remained unchanged or slightly declined with age to d 21. The mRNA abundance of SI increased and LAT2 decreased linearly (P < 0.001) with age, and the abundance of MGA and GLUT5 mRNA remained unchanged with age. There was an age x intestinal segment interaction (P < 0.001) for the abundance of EAAC1 and ATB0 mRNA. The abundance of EAAC1 mRNA increased from d 0 through 14 and remained stable to d 21 in the ileum, and it was low and slightly increased with age through d 21 in the duodenum and jejunum. The abundance of ATB0 mRNA generally increased from d 0 to 21 in the duodenum and ileum, and increased from d 0 to 7 and then decreased to d 21 in the jejunum. The abundance of SGLT1 and PepT1 mRNA was substantial at birth and transiently declined to d 1. The abundance of SGLT1 mRNA generally increased from d 1 to 21, and PepT1 mRNA abundance increased to d 3 and then plateaued through d 21. Postweaning, the mRNA abundance of all of these carbohydrate and protein assimilation related genes increased during the first day (3 d for ATB0) after weaning then declined to the levels at weaning in the jejunum and ileum, followed by a subsequent change pattern that varied among genes. During suckling, the mRNA abundance of LPH, SGLT1, and APA was greater in the duodenum and jejunum than the ileum (P < 0.001). The PepT1 and APN mRNA was evenly distributed among intestinal segments, and the expression of MGA, DPP IV, EAAC1, b0,+AT, ATB0, and LAT2 mRNA was generally greater in the jejunum and ileum than the duodenum or greatest in the ileum. Postweaning, the mRNA abundance of all of these carbohydrate and protein assimilation related genes examined was generally greater in the jejunum and ileum than the duodenum or highest in the ileum. From d 0 through 35, DMT1 and IREG1 mRNA was predominantly (P < 0.05) distributed in the duodenum, where the abundance of DMT1 and IREG1 mRNA increased with age during suckling, and then rapidly decreased after weaning. The protein expression of LPH and SI exhibited a similar developmental pattern as that for the mRNA abundance. Unlike the developmental regulation of their respective mRNA abundance, the protein expression of SGLT1 exhibited a general decline from suckling to postweaning. The protein expression of PepT1 gradually decreased with age from birth to d 35 in the duodenum, and initially declined from birth to the lowest value then slightly increased with age through d 21, followed by an increase to d 35 in the jejunum and ileum. In conclusion, the gene expression of these brushborder hydrolases and nutrient transporters was not only differentially regulated by age but also differentially distributed along the small intestine of piglets at early stages of life. These differences in ontogenetic regulation and the distribution may be related to the luminal substrate concentration as well as the nutrient categories, and the developmental regulation of these genes may occur not only at the transcriptional level but also at the posttranscriptional level.