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R C Ewan

Publications and source records attributed to R C Ewan.

At least 37 records · Page 2Linked to original sources
PubMed1993

Research note: vitamin E status of turkey poults as influenced by different dietary vitamin E sources, a bile salt, and an antioxidant.

An experiment was conducted to determine the effects of level and chemical form of dietary vitamin E on alpha-tocopherol status of poults. The effects of a dietary bile salt and an antioxidant on concentrations of alpha-tocopherol in serum and liver were also tested. Six dietary treatments were obtained by supplementing a corn-soybean meal diet with 12 IU of DL-alpha-tocopheryl acetate (TA)/kg (LE), 12 IU of TA plus 800 mg of sodium taurocholate/kg (LB), 12 IU of TA plus 500 mg of ethoxyquin/kg (LS), 12 IU of D-alpha-tocopheryl polyethylene glycol 1,000 succinate (TPGS)/kg (LT), 100 IU of TA/kg (HE), and 100 IU of TPGS/kg (HT). Growth rate and feed efficiency of poults were unaffected (P > .05) by dietary treatments. The HE diet increased alpha-tocopherol in liver (P < .01) at 14 and 21 days of age. Liver and serum alpha-tocopherol concentrations were unaffected by dietary TPGS (LT and HT diets) at any age. Serum alpha-tocopherol concentration was unaffected by dietary treatments at 5 days of age. The HE diet, however, increased (P < .01) serum alpha-tocopherol at 9, 14, and 21 days of age. Age-related changes in alpha-tocopherol concentration were observed. Both liver and serum alpha-tocopherol decreased markedly from 1 to 14 days of age. The HE diet only partly alleviated the reduction of alpha-tocopherol in liver and serum. The water-soluble form of vitamin E, TPGS, dietary sodium taurocholate, or dietary ethoxyquin, did not prevent the marked decline in alpha-tocopherol concentration of liver and serum during the 21-day experiment.

Animals↗
PubMed1991

Effect of trace minerals on the stability of vitamin E in swine grower diets.

The stability of alpha-tocopheryl acetate and inherent tocopherols in swine grower diets containing high levels of trace minerals was studied in a 12-wk experiment. Corn-soybean meal diets with either 0 or 1% crude soybean oil and without trace minerals added (NOTM) were supplemented with a standard trace mineral mix (TM), TM + 250 ppm of Cu, TM + 1,000 ppm of Fe, TM + 1,000 ppm of Zn, or TM + 100 ppm of Mn. Alpha-tocopheryl acetate decreased linearly (P less than .0001) during 12 wk of storage in diets containing NOTM, TM, Zn, or Mn at a rate of .015 mg/d. Addition of Fe (P less than .005) or Cu (P less than .05) increased the rate of alpha-tocopheryl acetate loss. The addition of soybean oil had no effect (P greater than .1) on the rate of alpha-tocopheryl acetate loss. The alpha-tocopherol levels of the NOTM diet decreased (P less than .01) by approximately 50% during the 12-wk storage period. Addition of TM alone in diets that did not contain soybean oil had no effect P greater than .1) on the rate of alpha-tocopherol loss. The addition of Cu, Fe, Zn, or Mn (P less than .05) to diets that did not contain soybean oil increased the rate of alpha-tocopherol loss in comparison with NOTM and TM diets. Addition of Cu decreased alpha-tocopherol below 10% of initial levels in approximately 10 d. The addition of soybean oil to the diets containing TM, Fe, Zn (P less than .005), or Mn (P less than .05) further increased the rate of alpha-tocopherol loss.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1991

Effect of vitamin E and copper on the vitamin E status and performance of growing pigs.

A 13-wk trial was conducted with 32 pigs to determine the effects of dietary Cu (250 ppm) and alpha-tocopheryl acetate (ATA, 22 IU/kg) on the performance, serum enzymes, serum and tissue tocopherols, and antibody production in growing pigs. Pigs were fed corn-soybean meal diets containing 21% CP the first 4 wk and 18% CP during the rest of the trial. All feed was stored a minimum of 14 d before it was fed. The addition of Cu decreased (P less than .01) the concentration of alpha-tocopherol in the feed. alpha-Tocopherol concentrations were less than .01 mg/kg in the starter diet and less than 2 mg/kg in the grower diet after 14 d of storage. Supplemental Cu or ATA had no effect on ADG, feed intake, or gain:feed during the first 4 wk. During wk 5 to 13, the addition of Cu to diets containing no ATA increased daily feed intake and decreased gain:feed, but with ATA addition, feed intake decreased and gain:feed increased, resulting in a Cu x ATA interaction (P less than .05). The addition of Cu or ATA had no effect (P greater than .1) on serum glutathione peroxidase or lactic dehydrogenase activity. Serum tocopherols were reduced (P less than .05) by the addition of Cu during wk 1 to 4, 6 (P less than .01), and 7 (P less than .05) and increased (P less than .01) by ATA addition during the entire experiment. The addition of ATA increased the tocopherol concentrations in bile, ham, heart, pancreas, kidney, spleen, liver, psoas and longissimus muscle (P less than .01), kidney fat, backfat, and adrenal gland (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effect of excess dietary copper, iron or zinc on the tocopherol and selenium status of growing pigs.

Two experiments were conducted to evaluate the effect of the addition of high levels of Cu (as CuSO4), Fe (as FeSO4) or Zn (as ZnO) to swine starter and grower diets on performance and vitamin E and Se status. The stability of natural tocopherols in mixed feeds was evaluated during storage. Addition of 1,000 ppm Fe or 1,000 ppm Zn had no effect on rate or efficiency of weight gain in either experiment. In Exp. 1, the addition of 250 ppm Cu improved daily gain and efficiency of feed utilization (P less than .05) during the first 3 wk of the experiment. Copper had no effect on pig performance during the rest of Exp. 1 or in Exp. 2. Serum lactate dehydrogenase or glutathione peroxidase activity was not affected (P greater than .1) by any of the mineral additions. Serum tocopherols were not affected by the mineral treatments in Exp. 1. In Exp. 2, addition of 250 ppm Cu decreased (P less than .01) serum tocopherol levels throughout the 8-wk experiment. The alpha-tocopherol levels of the starter diet decreased (P less than .05) during storage. Addition of 250 ppm Cu (P less than .01) or 1,000 ppm Fe (P less than .05) or 1,000 ppm Zn (P less than .05) increased the destruction of alpha-tocopherol in the starter diet. Alpha- and gamma-tocopherol levels of the starter diet decreased to near zero in 22 d in the presence of 250 ppm Cu. In the grower diet, the addition of 250 ppm Cu (P less than .01) or 1,000 ppm Fe (P less than .05) increased the destruction of tocopherols.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effect of dietary sodium bicarbonate on leg structure in Duroc swine that differ genetically for leg weakness.

Two trials were conducted to evaluate the effect of dietary replacement of .30% sodium chloride (NaCl) with a sodium-equivalent amount of sodium bicarbonate (NaHCO3) on leg weakness in swine. Three lines of Duroc swine established by six generations of divergent selection for front leg structure were used. In the first trial, a total of 80 low-line (increased leg weakness), 75 high-line (decreased leg weakness), 80 control-line (intermediate leg weakness) and 80 high x low pigs were used. Pigs were assigned within litter to an experimental or control diet and tested from approximately 37 to 104 kg live weight. The experimental diet contained .43% NaHCO3, replacing .30% NaCl in the control diet. Pigs had ad libitum access to feed. In the second trial, 48 high- and 48 low-line pigs were fed the same diets from 29 to 104 kg. At the completion of each trial, pigs were scored for various leg traits. The model used for statistical analyses included the effects of replicate, genetic line, dietary treatment and the dietary treatment x genetic line interaction. Trials were analyzed separately. Results indicated that there was no significant improvement in clinical signs of leg weakness due to dietary supplementation with NaHCO3 for front leg structure and movement, rear leg movement or rear toe size. Rear hock angle was improved in Trial 1 (P less than .05) but was reduced in Trial 2 (P less than .10).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1986

In vivo metabolism of leucine and alpha-ketoisocaproate in the pig: influence of dietary glucose or sucrose.

The influence of dietary glucose (G) and sucrose (S) on leucine metabolism was evaluated in 10 immature pigs. The diets were isoenergetic and isonitrogenous with 40% of energy being derived from G or S. Animals were fed their diets at least 1 wk prior to the study. Each animal was studied by using a continuous infusion of L-[4,5-3H]leucine and [U-14C] alpha-ketoisocaproate (KIC) to permit measurement of the metabolism of leucine. After a meal, the pigs fed the glucose meal had higher mean plasma glucose and insulin concentrations than pigs fed a sucrose-containing meal. Arterial KIC concentration decreased after feeding either meal, but the arterial leucine concentration remained unchanged. In pigs fed sucrose, plasma fructose increased after the meal and was cleared by the hind limb in the same proportion as plasma glucose (11%). The hind limb glucose clearance was 16% in the glucose-fed pigs. Animals fed the glucose meal had three times greater hind limb uptake of leucine than animals fed the sucrose meal. No dietary influence on hind limb metabolism of KIC could be detected from arterial-venous differences. The whole-body leucine-KIC kinetic data suggested that preprandial tissue proteolysis was greater in pigs fed glucose than in those fed sucrose. Postprandial protein synthesis increased (24%) over fasting values only in pigs fed glucose. This was accompanied by a decrease in the percentage of the leucine pool converted to KIC. These observations indicate that both pre- and postprandial aspects of protein metabolism can be influenced by the dietary carbohydrate source.

Animals↗
PubMed1984

Effect of selenium on performance, serum selenium concentration and glutathione peroxidase activity in pigs.

Pigs from sows fed a diet deficient in Se and low in vitamin E were fed a Torula yeast diet supplemented with 100 IU dl-alpha-tocopheryl acetate/kg of diet. Dietary treatments were levels of supplemental Se of 0, .025, .050, .075 or .100 ppm. Some death loss occurred in pigs receiving no supplemental Se at approximately 5 wk of age. Autopsy revealed liver and heart lesions typical of vitamin E-Se deficiency. Selenium supplement had no significant effect on average daily gain, feed intake or gain to feed ratio for the 4-wk experiment. Selenium status of pigs was determined by serum Se concentration and serum glutathione peroxidase (GSH-Px) activity. Serum Se increased linearly (P less than .01) with increasing supplemental Se. Serum GSH-Px activity increased linearly (P less than .01) and quadratically (P less than .05) with increasing supplemental Se. With time, the level of serum Se and GSH-Px activity decreased in unsupplemental pigs, but increased in pigs fed diets supplemented with Se and resulted in significant interactions (P less than .01) between dietary Se level and time on experiment. The correlation between serum Se concentration and GSH-Px activity was .81 (P less than .01).

Animals↗
PubMed1984

Effect of supplemental selenium on pancreatic function and nutrient digestibility in the pig.

The effect of Se deficiency on pancreatic digestive enzyme activity and nutrient digestibility was studied by using pigs weaned at 3 wk of age from sows fed a diet deficient in Se and low in vitamin E. Pigs were fed a Torula yeast diet supplemented with 100 IU dl-alpha-tocopheryl acetate/kg of diet. Treatments were levels of supplemental Se of 0, .025, .050, .075 or .100 ppm. Apparent digestibility was determined at the end of the second and fourth week. Digestive enzyme activity, glutathione peroxidase (GSH-Px) activity and Se concentration were determined in pancreatic tissue at the end of the 4-wk experiment. Selenium concentration in the pancreas increased linearly (P less than .01) and quadratically (P less than .05) in response to increasing level of Se supplementation. The correlation between pancreas Se level and GSH-Px activity was .36 (P less than .05). Supplementation of Se had no effect on pancreas weight, protein content or the activity of pancreatic trypsin, chymotrypsin, alpha-amylase or lipase. Apparent digestibility increased linearly for dry matter (P less than .01) and N (P less than .05) as Se supplementation increased. There was however, no significant effect on ether extract digestibility. Apparent digestibilities were higher (P less than .01) at 4 wk than those measured at 2 wk.

Animals↗
PubMed1984

Energy utilization of weanling pigs raised under pen conditions.

Two comparative slaughter experiments were conducted to evaluate the energy utilization of weanling pigs raised in groups under pen conditions. In Trial 1, 64 weanling pigs were kept in groups of four and fed every 12 h. The pigs were fed either ad libitum during the two daily feedings or 80, 60 or 40% of the intake/kilogram body weight (BW) of the 100% intake group. The efficiency of dietary energy and N utilization for carcass energy and N gains increased quadratically (P less than .01) with increasing feed intake. The daily metabolizable energy (ME) requirement for maintenance (MEm) was calculated to be 115 kcal X d-1 (kg X 75)-1. Above maintenance, the ME of the diet was utilized for carcass energy gain with an efficiency of 50%. Trial 2 was conducted to examine the energy and N utilization of weanling pigs kept either individually in cages or in groups of four under pen conditions. Twelve pigs were allotted to each pen type and fed at levels of 2, 3.5 or 5% of their BW daily. Increasing the level of intake, quadratically increased (P less than .01) the efficiency of ME and digestible N (DN) utilization for carcass energy and N gains. The apparent digestibilities of energy and N decreased linearly (P less than .05) while rate of passage increased linearly (P less than .05) with increasing feed intake. When compared with the individually caged pigs, the grouped pigs showed lower apparent digestibility of energy (P less than .05) but improved efficiency (P less than .05) of ME and DN utilization for carcass energy and N gains.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Effect of selenium on the subcellular distribution of glutathione peroxidase in rat liver, epididymal fat pad and seminal vesicle.

The effect of dietary selenium on the subcellular distribution of selenium-dependent glutathione peroxidase (SeGSH-Px) activity in rat liver, epididymal fat pad, and seminal vesicle was determined. Tissues were fractionated by differential centrifugation, and the subcellular distribution of SeGSH-Px activity was determined by comparison with the distribution of biochemical marker enzymes. Liver SeGSH-Px activity was located in both the cytosol and mitochondria. In epididymal fat pad and seminal vesicle, SeGSH-Px activity was located primarily in the cytosol; association with another subcellular organelle, however, was indicated. In liver and epididymal fat pad, SeGSH-Px activity increased linearly, and, in the seminal vesicle, increased linearly and quadratically, with increasing dietary selenium concentration. Distribution of SeGSH-Px activity among the cellular fractions from the tissues, however, was not affected by dietary selenium supplementation.

Adipose Tissue↗
PubMed1977

Effects of intramuscular injections of selenium and vitamin E on selenium-vitamin E deficiency in young pigs.

Effects of intramuscular injections of selenium and vitamin E on lesions in pigs with selenium-vitamin E deficiency syndrome were determined in 2 factorial experiments, using a total 69 pigs. The pigs were fed a selenium-vitamin E deficient, 22.3% protein ration, supplemented with methionine, minerals, and vitamins. Weekly intramuscular injections of isotonic saline solution, vitamin E, selenium, or vitamin E and selenium were given to the respective treatment groups. Selenium-vitamin E deficiency lesions occurred only in pigs that were given saline injections. Weekly intramuscular injections of either selenium (as selenous acid buffered to pH (7.3) at the rate of 0.05 mg/kg of body weight or vitamin E at the rate of 20 IU/kg of body weight or the combination of selenium and vitamin E prevented cardiac and skeletal myodegeneration, hepatic necrosis, and death. Significant increases of serum aspartate aminotransferase activity values were noted in pigs with liver, heart, or skeletal muscle lesions, but these increases were not correlated with the extent of the lesions. Vascular lesions, epicardial and endocardial hemorrhages, and yellow discoloration of body fat were not features of this experimentally induced disease. These lesions may be related to factors other than the deficiency of selenium, vitamin E, or selenium and vitamin E in rations previously used in reported studies.

Animals↗
PubMed1976

Effect of selenium on rat growth, growth hormone and diet utilization.

Female rats were fed a selenium-deficient diet composed of Torula yeast, sucrose, vitamins (including tocopheryl acetate) and minerals from weaning and during breeding, gestation and lactation. The offspring were used to study the effects of selenium on growth, diet utilization and growth hormon status. The Torula yeast diet containing 200 IU dl-alpha-tocopheryl acetate was fed alone or supplemented with 0.025 or 0.1 ppm of selenium as selenite. Rats fed the selenium-supplemented diets grew significently faster and consumed significantly more diet than rats fed the unsupplemented diet. Anterior pituitary weights were lower in selenium-deficient rats, but if expressed per unit of body weight, were similar to pituitary weight of selenium-supplemented animals. Total growth hormone in the anterior pituitary was reduced in selenium-deficient rats. A metabolism study indicated that rats allowed ad libitum access to supplemented diets consumed more diet and obtained more metabolizable energy from the diet than rats fed the deficient diet. It the intake of rats fed the supplemented diets was limited to that of rats allowed ad libitum access to deficient diet, growth of rats was similar. However, metabolizable energy content of the diet increased quadratically and nitrogen digestibility increased linearly as thelevel of selenium increased. Selenium deficiency reduced growth primarily by decreased diet consumption, but also reduced the utilization of energy and nitrogen.

Animals↗