The failure of selenium supplementation to prevent copper-induced liver damage in Fischer 344 rats.

This study evaluates the ability of selenium (Se) supplementation to prevent experimental copper (Cu)-induced hepatocellular damage. Weanling male Fischer 344 rats were randomly assigned to groups of 15, 3 groups (A,B,C) were fed Cu-loaded diets (containing 2000 microg/g copper, added as CuSO4) and different levels of Se (added as Na2SeO3 x 5H2O) as follows: A) Cu-loaded/Se adequate diet (0.4 microg/g Se, fed basis); B) Cu-loaded/Se-supplemented diet (2 microg/g Se); and C) Cu-loaded/Se-deficient diet (< 0.2 microg/g). Three additional groups (D,E,F) were fed diets containing adequate levels of Cu (14 microg/g Cu, fed basis) and different levels of Se as follows: D) Cu-adequate/Se-adequate diet; E) Cu-adequate/Se-supplemented diet (2 microg/g Se); and F) Cu-adequate/Se-deficient (< 0.2 microg/g) diet. After 4, 8, and 12 weeks on the experimental diets, liver samples were processed for histology, histochemistry, metal analysis, glutathione peroxidase (GSH-Px) measurement, and quantification of malondialdehyde (MDA). Morphologic changes characteristic of Cu-associated hepatitis, without an increase in hepatic MDA levels, were seen in all Cu-loaded rats in each sampling. Similar changes occurred in rats fed Se-adequate, Se-supplemented and Se-deficient diets. This study demonstrates that Fischer 344 rats fed 2000 microg/g Cu develop morphologic changes due to Cu toxicity without evidence of lipid peroxidation. Furthermore, Se supplementation does not result in protection against Cu-induced liver injury.     

Morphological and biochemical assessment of the liver response to excess dietary copper in Fischer 344 rats.

The aim of this study was to determine the amount of excess dietary copper (Cu) necessary to experimentally induce liver lesions characteristic of Cu-associated disease in Fischer 344 rats. Male weanling Fischer 344 rats of uniform age were divided into 6 groups (n = 5) and fed a rodent diet containing 18 (control), 750, 1000, 1250, 1500, and 2000 microg/g Cu added as CuSO4. Rats were euthanized after 3 months on the experimental diets and their livers processed for histology, histochemistry, Cu analysis (by atomic absorption spectrophotometry), and quantification of malondialdehyde (MDA) by the thiobarbituric acid reaction. Hepatic Cu levels were significantly higher (P < 0.01) in rats receiving over 1000 microg/g Cu compared to the controls (means for each diet: control = 4.8 microg/g, 750 microg/g Cu = 39.6 microg/g, 1000 microg/g Cu = 111.2 microg/g, 1250 microg/g Cu = 389 microg/g, 1500 microg/g Cu = 509.4 microg/g, and 2000 microg/g Cu = 766 microg/g). Histological lesions increased gradually according to the level of dietary Cu. Significant morphologic changes (necrosis, portal inflammation, hyaline remnants) and reduced growth rate occurred in rats receiving over 1250 microg/g Cu. However, no significant differences were found for MDA levels between groups. The present study demonstrates that compared to other species, very high levels of excess dietary Cu are needed to induce significant liver injury in Fischer 344 rats. Increased MDA content was not detected in rats with morphologic evidence of liver damage, suggesting that lipid peroxidation may not play a major role in this model of Cu toxicity.     

Effects of dietary copper and molybdenum on tansy ragwort (Senecio jacobaea) toxicity in sheep

Dried tansy ragwort (Senecio jacobaea), which contains pyrrolizidine alkaloids (PA), was fed to sheep to determine whether PA consumption influenced liver Cu concentrations. Nine Polypay wether lambs were allotted to 3 groups according to the diets: control diet + 50 micrograms of Cu/g of feed (control + Cu); tansy ragwort (TR) diet + 50 micrograms of Cu/g of feed (TR + Cu); and TR diet + 50 micrograms of Cu/g of feed and 10 micrograms of Mo/g of feed (TR + Cu + Mo). Liver Cu concentrations were sharply increased (13-fold) after 8 weeks of feeding the diets, and then decreased slightly. There were no significant differences in concentrations of liver Cu among treatment groups. All lambs in the group fed TR + Cu + Mo died by the end of 23 weeks, with the usual signs of PA poisoning, including liver necrosis, hepatic megalocytosis, and biliary hyperplasia. The TR intake was about 2.7 to 3.0 kg/kg of their initial body weight. All lambs in the group fed the control + Cu diet survived. The results indicated that sheep fed TR do not preferentially accumulate liver Cu. There was an indication that dietary Mo increased susceptibility to TR intoxication.     

Effect of dietary alfalfa on zearalenone toxicity and metabolism in rats and swine

Experiments were conducted with rats and swine to determine the potential of dietary alfalfa as a treatment for zearalenone (Z) toxicosis. Ninety-six female weanling Wistar rats were fed a casein-based semipurified diet containing 0, 15 or 25% alfalfa and 0 or 250 micrograms Z/g feed. Exposure to Z for 14 d resulted in reduced growth, feed consumption and feed efficiency as well as kidney and liver enlargement and reduced activity of 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD). Z had no effect on uterine weight. Including alfalfa in these diets reduced the inhibitory effects of Z on growth and feed consumption, minimized Z-induced liver enlargement and increased hepatic 3 alpha-HSD activity. Dietary alfalfa also reduced concentrations of residual Z and zearalenols (Zl) in liver. In a second experiment, 108 Yorkshire gilts weighing 8 to 11 kg were fed diets containing 0, 15 or 25% alfalfa and 0, 10, 20 or 40 micrograms Z/g feed for 4 wk. Z caused uterine enlargement when fed as low as 10 micrograms/g feed, although no effects were seen in growth rate, feed consumption or feed efficiency. Alfalfa decreased uterine enlargement (P less than .05), but caused a depression in feed efficiency (P less than .05). Hepatic 3 alpha-HSD activity was five times lower in swine than in rats, although activity still tended to decrease with Z and increase with alfalfa feeding. Residues of Z and Zl in pig liver indicated species differences in the metabolism of Z. These studies show that dietary alfalfa promotes Z metabolism in rats and that this feedstuff may also be useful for treating Z toxicosis in livestock.     

Effect of dietary supplementation with stearic acid on the severity of myocardial lesions

Histological studies were conducted on ventricular myocardium obtained from male rats of the Sprague-Dawley strain after 16 weeks of feeding diets containing 20 per cent (w/w) soybean oil, low erucic acid rapeseed oil or high erucic acid rapeseed oil. Additional groups of rats were fed similar diets supplemented with up to 8 g/kg of tristearin. Increasing dietary intake of stearic acid normalised the plasma ratio of C16:0 to C18:0 for rapeseed oil treatments to ratios analogous to that observed for rats fed soybean oil. Tristearin supplementation did not have a significant effect on myocardial lesion incidence but decreased the severity of lesions observed for rapeseed oil treatments.     

Selenium status in adult cats and dogs fed high levels of dietary inorganic and organic selenium

Cats (Felis catus) maintain greater blood Se concentrations compared with dogs (Canis familiaris) and, unlike dogs, show no signs of chronic Se toxicity (selenosis) when fed dietary organic Se (selenomethionine) concentrations of 10 μg/g DM. This study investigated the response of cats and dogs to high dietary concentrations of sodium selenite and organic Se to determine differences in metabolism between both species. In 2 consecutive studies, 18 adult cats and 18 adult dogs of with equal numbers of each sex were fed a control diet (0.6 μg Se/g DM) or the control diet supplemented to 8 to 10 μg Se/g DM from Na(2)SeO(3) or organic Se for 3 wk. All animals were fed the control diet 1 mo before the start of the study and blood samples were taken on d 0 and 21. The Se balance was assessed during the final week and a liver biopsy was obtained on the final day of the study. Measurements included plasma Se concentrations, plasma glutathione peroxidise (GPx) activities, plasma Se clearance, Se intake, and urinary Se excretion. No clinical signs of selenosis were observed in the cats or dogs, and apart from Se clearance, form of Se had no effect on any of the measurements. Apparent fecal Se absorption was greater in the dogs fed both forms of Se, while greater plasma Se concentrations were observed in the cats on both the control and supplemented diet (P = 0.034). Cats fed the supplemented diets had lower hepatic Se concentrations (P < 0.001) and excreted more Se in urine (P < 0.001) compared with dogs. Furthermore, cats fed the Na(2)SeO(3) supplement had greater Se clearance rates than dogs (P < 0.001). There was no effect of species on plasma GPx activity. We conclude that cats can tolerate greater dietary Se concentrations as they are more efficient at excreting excess Se in the urine and storing less Se in the liver.     

Effects of dietary copper source and concentration on carcass characteristics and lipid and cholesterol metabolism in growing and finishing steers

We conducted an experiment to determine the effects of dietary copper (Cu) source and level on carcass characteristics, longissimus muscle fatty acid composition, and serum and muscle cholesterol concentrations in steers. Sixty Angus and Angus x Hereford steers were stratified by weight and initial liver Cu concentration within a breed and randomly assigned to treatments. Treatments consisted of: 1) control (no supplemental Cu); 2) 20 mg Cu/kg DM from Cu sulfate (CuSO4); 3) 40 mg Cu/kg DM from CuSO4; 4) 20 mg Cu/kg DM from Cu citrate; 5) 20 mg Cu/kg DM from Cu proteinate; and 6) 20 mg Cu/kg DM from tribasic Cu chloride. A corn silage-soybean meal-based diet was fed for 56 d. Steers were then switched to a high-concentrate diet. Equal numbers (n = 5) of steers per treatment were slaughtered after receiving the finishing diets for either 101 or 121 d. Serum cholesterol was not affected by treatment during the growing phase but was decreased (P < .05) in steers supplemented with Cu by d 84 of the finishing period and remained lower (P < . 05) at subsequent sampling periods. Longissimus muscle cholesterol concentration tended to be reduced (P < .11) by Cu supplementation. Hot carcass weight and backfat were lower (P < .05) in animals receiving supplemental Cu. However, Cu-supplemented and control steers had similar marbling scores. Longissimus muscle polyunsaturated fatty acid concentrations (18:2 and 18:3) were increased (P < .07) and saturated fatty acid concentrations tended (P < . 11) to be reduced by Cu supplementation. These results indicate that as little as 20 mg of supplemental Cu/kg diet can reduce backfat and serum cholesterol and increase muscle polyunsaturated fatty acids in steers fed high-concentrate diets.     

Effect of dietary supplementation of astaxanthin by Phaffia rhodozyma on lipid peroxidation, drug metabolism and some immunological variables in male broiler chicks fed on diets with or without oxidised fat

1. Effects of dietary supplementation of astaxanthin (Ax) provided from Phaffia rhodozyma on lipid peroxidation, hepatic drug metabolism, antibody titres to sheep red blood cells (SRBC) and splenocyte proliferation to mitogens were determined in male broiler chicks. 2. Chicks, one week old, were given diets with or without oxidised fat (0 or 3.7 meq of peroxide value (POV)/kg diet) and/or Ax (0 or 100 mg/kg diet) for 14 d, ad libitum. 3. Lipid peroxidation, estimated by 2-thiobarbituric acid reactants values in liver, spleen, heart, plasma and hepatic microsomes, were increased by feeding a diet containing oxidised fat (P<0.05) but were not affected by Ax feeding. 4. Cytochrome P-450 contents in hepatic microsome tended to be increased by feeding Ax. 5. Anti-SRBC titre was not affected by oxidised fat or Ax feeding, while plasma immunogloblin (Ig) G concentration was increased by Ax feeding but was not affected by oxidised fat feeding. 6. When chicks were fed on the diet without oxidised fat, Ax enhanced splenocyte proliferation stimulated by both concanavalin A and pokeweed mitogen, while in chicks fed on a diet containing oxidised fat, Ax reduced the proliferation (P<0.01 for Ax and oxidised fat interaction). 7. The results indicated that dietary supplementation of Ax from Phaffia rhodozyma had an impact on T cell proliferation and Ig G production as a part of acquired immunity, but was not effective in preventing lipid peroxidation in male broiler chicks.     

Effects of organic selenium supplementation on growth performance, carcass measurements, tissue selenium concentrations, characteristics of reproductive organs, and testis gene expression profiles in boars

The objective was to compare growth and physiological responses in boars fed diets supplemented with organic or inorganic sources of Se. At weaning, crossbred boars (n = 117; 8.3 kg of BW) were placed in nursery pens (3 boars/pen) and assigned within BW blocks to receive on an ad libitum basis 1 of 3 dietary treatments: I) basal diets with no supplemental Se (controls), II) basal diets supplemented with 0.3 mg/kg of organic Se, and, III) basal diets supplemented with 0.3 mg/kg of sodium selenite (13 pens/dietary treatment). Average daily gain (470 g/d), ADFI (896 g/d), and G:F (0.54) were similar among groups. Blood Se concentrations were greater (P < 0.01) for boars consuming organic Se (107.5 ± 4.8 μg/L) or sodium selenite (114.7 ± 4.8 μg/L) compared with controls (28.4 ± 4.8 μg/L). Intact pens of boars (11 pens/dietary treatment) were moved to a grow-finish barn and continued to receive appropriate diets on an ad libitum basis. Average daily gain (1,045 g/d) and ADFI (2,716 g/d) were similar among groups. Gain:feed was affected by treatment (P = 0.02) and was greater (P < 0.06) for boars fed organic Se (0.378 ± 0.004) compared with boars fed sodium selenite (0.368 ± 0.004) or controls (0.363 ± 0.004). Blood Se concentrations were greater (P < 0.01) in grow-finish boars consuming organic Se (198.9 ± 5.5 μg/L) than boars consuming sodium selenite (171.4 ± 5.4 μg/L) or controls (26.7 ± 5.4 μg/L). Treatment did not affect (P > 0.15) HCW, dressing percent, carcass length, LM area, standardized fat-free lean, lean percentage, backfat thickness, visual color, firmness, marbling, or Minolta loin color scores. Selenium supplementation did not affect (P > 0.17) testis or accessory sex gland sizes. Concentrations of Se in loin, liver, kidney, testis, cauda epididymis, and accessory sex glands were greatest (P < 0.01) in boars receiving organic Se, intermediate in boars receiving sodum selenite, and least in control boars. Microarray analysis of testis gene expression did not detect differences (P > 0.05) due to dietary treatment. Testis gene expression of glutathione peroxidase 4, as determined using quantitative PCR, was increased (P < 0.01) in boars fed organic Se compared with those fed sodium selenite. In summary, dietary supplementation of boars with organic Se failed to alter ADG or ADFI but enhanced G:F during grow-finish. More research is needed to discern the mechanism by which organic Se improves feed efficiency in boars.     

Effects of dietary supplementation with an organic source of selenium on characteristics of semen quality and in vitro fertility in boars

Semen characteristics in boars fed organic or inorganic sources of Se were assessed in 3 experiments. Crossbred boars were randomly assigned at weaning to 1 of 3 dietary treatments: I) basal diets with no supplemental Se (control), II) basal diets with 0.3 mg/kg of supplemental Se from an organic source (Sel-Plex, Alltech Inc., Nicholasville, KY), and III) basal diets supplemented with 0.3 mg/kg of supplemental Se from sodium selenite (Premium Selenium 270, North American Nutrition Co. Inc., Lewisburg, OH). For Exp. 1, semen was collected from boars (n = 10/dietary treatment) on 5 consecutive days at 15 mo of age. Effects of treatment × day were detected for the proportions of progressively motile (P = 0.02) and rapidly moving (P = 0.03) spermatozoa, and measures of sperm velocity, including path velocity of the smoothed cell path (P = 0.05) and average velocity measured in a straight line from the beginning to the end of the track (P = 0.05). Negative effects of day of semen collection on sperm motility were least pronounced in boars fed Sel-Plex. Experiment 2 was conducted when boars were 17 mo of age, and semen was collected (n = 10 boars/dietary treatment), diluted in commercially available extenders, and stored at 18°C for 9 d. Effects of treatment × day were detected for percentages of motile (P = 0.01) and static (P = 0.01) spermatozoa, amplitude of lateral head displacement (P = 0.02), frequency with which the sperm track crossed the sperm path (P = 0.04), straightness (P = 0.01), and average size of all sperm heads (P = 0.03). In general, sperm cells from boars fed Sel-Plex were better able to maintain motility during liquid storage compared with boars fed sodium selenite. For Exp. 3, semen was collected from boars (n = 6/dietary treatment) at 23 mo of age, and spermatozoa were evaluated at d 1 and 8 after semen collection using in vitro fertilization procedures. There was a tendency for an effect (P = 0.11) of dietary treatment on fertilization rate with Sel-Plex-fed boars having the greatest value (70.7%). The results of this study suggest that there are positive effects of dietary supplementation with Sel-Plex on boar semen characteristics and that organic Se supplementation may help ameliorate the negative effects of semen storage on characteristics of sperm motility.     

Effects of dietary supplementation of selenium and iodine on growth performance,carcass characteristics and histology of thyroid gland in goats

This study assessed the effects of dietary selenium (Se), iodine (I) and a combination of both on growth performance, thyroid gland activity, carcass characteristics and the concentration of iodine and selenium in Longissimus lumborum (LL) muscle in goats. Twenty‐four bucks were randomly assigned to four dietary treatments: control (CON), basal diet without supplementation, basal diet + 0.6 mg Se/kg dry matter (DM) (SS), 0.6 mg I/kg DM (IP), or combination of 0.6 mg/kg DM Se and 0.6 mg/kg DM I (SSIP) and fed for 100 days. Animals fed diet SSIP exhibited higher (P < 0.05) body weight and better feed conversion ratio (FCR) than those fed other diets. Dressing percentage of goats fed the supplemented diets was higher (P < 0.05) than that of the control. Carcasses from the IP group had higher (P < 0.05) total fat proportion than the SSIP group. The levels of both elements were significantly elevated (P < 0.05) in LL muscle in supplemented goats. Thyroid follicular epithelial cells of IP and SSIP animals were significantly higher than those of CON and SS groups. The study demonstrated that the combined Se and I dietary supplementation improves growth performance, carcass dressing percentage and increases the retention of Se and I in goat meat.     

Effect of the chemical form of supranutritional selenium on selenium load and selenoprotein activities in virgin, pregnant, and lactating rats

Virgin, pregnant, and lactating rats were used to assess the influence of selenomethionine and selenocystine, fed at four to seven times the daily Se requirement (supranutritional), on Se load and selenoprotein activities. Female Sprague Dawley rats (n = 48; age = 13 wk), reared on a low-Se torula yeast diet, were assigned to one of three reproductive states (n = 16 per reproductive state) to occur simultaneously: virgin, pregnant, and lactating. Once reproductive state was achieved, rats were fed (ad libitum) either l-selenomethionine (n = 24) or L-selenocystine (n = 24) diets providing 2.0 microg Se/g of diet (as-fed basis) for 18 d, and then killed. Lactating rats consuming selenomethionine had the greatest Se concentration in the brain, with pregnant rats being intermediate, and virgin rats having the least (P < 0.02). When selenocystine was fed, the concentration of Se in the brain was greater (P = 0.008) in lactating rats, but not different (P = 0.34) between pregnant and virgin rats. Selenium concentrations in the heart, liver, lung, muscle, spleen, plasma, placenta, uterus, and fetus were greatest (P < 0.001) in rats consuming selenomethionine. Brain, kidney, and liver thioredoxin reductase, and brain, erythrocyte, kidney, and liver glutathione peroxidase activities did not differ (P = 0.13 to P = 0.85) between Se treatments. Lactating rats exhibited the greatest (P < 0.006) Se concentration in the heart, lung, muscle, plasma, and spleen compared with pregnant and virgin rats. Thioredoxin reductase was greatest (P < 0.004) in the brain of pregnant rats, greatest (P < 0.004) in the liver of lactating rats, and greater (P < 0.03) in the kidney of lactating and pregnant vs. virgin rats. Regardless of reproductive state, supranutritional Se (2.0 microg/g of diet) fed as selenocystine resulted in less Se load, and when fed as selenomethionine, was equally available for thioredoxin reductase synthesis as the Se in selenocystine. Independent of dietary Se chemical form, thioredoxin reductase activity was responsive to reproductive state.     

Effects of riboflavin supplementation and selenium source on selenium metabolism in the young pig

The effect of dietary riboflavin (B2) supplementation and selenium (Se) source on the performance and Se metabolism of weanling pigs was studied. Pigs fed a B2-supplemented (10 mg/kg) casein-glucose diet for 18 d gained faster than pigs fed the B2-unsupplemented diet. Percentage active erythrocyte glutathione reductase (GR) declined rapidly when pigs were placed on the B2-unsupplemented diet and was lower (P less than .01) than that of B2-supplemented pigs after 12 d on test. Percentage active erythrocyte GR values fell below 50% before other B2 deficiency signs became evident. Supplementation of diets with 10 mg B2/kg resulted in increased kidney and muscle glutathione peroxidase (GSH-Px) activity. The Se concentration of liver and heart increased and plasma Se levels decreased with dietary B2 supplementation. Riboflavin supplementation and Se source did not alter apparent Se absorption, but B2 supplementation decreased urinary Se and thus increased Se retention. Also, there was less urinary Se excretion when selenomethionine was the dietary Se source and consequently more Se was retained than when sodium selenite was the dietary Se source. In a final trial, B2 supplementation increased kidney, muscle, heart and brain GSH-Px activity when sodium selenite was the dietary Se source, but not when selenomethionine was the dietary Se source.     

Effect of dietary copper source (cupric citrate and cupric sulfate) and concentration on growth performance and fecal copper excretion in weanling pigs

In each of two experiments, 924 pigs (4.99 kg BW; 16 to 18 d of age) were assigned to 1 of 42 pens based on BW and gender. Pens were allotted randomly to dietary copper (Cu) treatments that consisted of control (10 ppm Cu as cupric sulfate, CuSO4 x 5H2O) and supplemental dietary Cu concentrations of 15, 31, 62, or 125 ppm as cupric citrate (CuCit), or 62 (Exp. 2 only), 125 (Exp. 1 only), or 250 ppm as CuSO4. Live animal performance was determined at the end of the 45-d nursery phase in each experiment. On d 40 of Exp. 2, blood and fecal samples were collected from two randomly selected pigs per pen for evaluation of plasma and fecal Cu concentrations and fecal odor characteristics. In Exp. 1, ADG, ADFI, and G:F were increased (P < 0.05), relative to controls, when pigs were fed diets containing 250 ppm Cu as CuSO4. Pigs fed diets containing 125 ppm Cu as CuCit had increased (P < 0.05) ADG compared with pigs fed diets supplemented with 15 or 62 ppm Cu as CuCit. The ADG, ADFI, and G:F did not differ among pigs fed diets containing 125 and 250 ppm Cu as CuSO4 or 125 ppm Cu as CuCit. In Exp. 2, pigs fed diets containing 250 ppm Cu as CuSO4 had improved (P < 0.05) ADG, ADFI, and G:F compared with controls. In addition, ADG, ADFI, and G:F were similar when pigs were fed diets containing either 250 ppm Cu as CuSO4 or 125 ppm Cu as CuCit. Pigs fed diets containing 62 ppm Cu as CuSO4 or CuCit had similar ADG, ADFI, and G:F. Plasma Cu concentrations were not affected by dietary Cu source or concentration, but fecal Cu concentrations were increased (P < 0.05) as the dietary concentration of Cu increased. Pigs consuming diets supplemented with 125 ppm Cu as CuCit had fecal Cu concentrations that were lower (P < 0.05) than pigs consuming diets supplemented with 250 ppm Cu as CuSO4. Fecal Cu did not differ in pigs receiving diets supplemented with 62 ppm Cu as CuSO4 or CuCit. Odor characteristics of feces were not affected by Cu supplementation or source. These data indicate that 125 and 250 ppm Cu gave similar responses in growth, and that CuCit and CuSO4 were equally effective at stimulating growth and improving G:F in weanling pigs. Fecal Cu excretion was decreased when 125 ppm Cu as CuCit was fed compared with 250 ppm Cu as CuSO4. Therefore, 125 ppm of dietary Cu, regardless of source, may provide an effective environmental alternative to 250 ppm Cu as CuSO4 in weanling pigs.     

Effects of selenium supply and dietary restriction on maternal and fetal metabolic hormones in pregnant ewe lambs

The objective of these studies was to evaluate the effects of dietary restriction and Se on maternal and fetal metabolic hormones. In Exp. 1, pregnant ewe lambs (n = 32; BW = 45.6 +/- 2.3 kg) were allotted randomly to 1 of 4 treatments. Diets contained (DM basis) either no added Se (control), or supranutritional Se added as high-Se wheat at 3.0 mg/kg (Se-wheat), or sodium selenate at 3 (Se3) and 15 (Se15) mg/kg of Se. Diets (DM basis) were similar in CP (15.5%) and ME (2.68 Mcal/kg). Treatments were initiated at 50 +/- 5 d of gestation. The control, Se-wheat, Se3, and Se15 treatments provided 2.5, 75, 75, and 375 microg/kg of BW of Se, respectively. Ewe jugular blood samples were collected at 50, 64, 78, 92, 106, 120, and 134 d of gestation. Fetal serum samples were collected at necropsy on d 134. In Exp. 2, pregnant ewe lambs (n = 36; BW 53.8 +/- 1.3 kg) were allotted randomly to treatments in a 2 x 2 factorial arrangement. Factors were nutrition (control, 100% of requirements vs. restricted nutrition, 60% of control) and dietary Se (adequate Se, 6 microg/kg of BW vs. high Se, 80 microg/kg of BW). Selenium treatments were initiated 21 d before breeding, and nutritional treatments were initiated on d 64 of gestation. Diets were 16% CP and 2.12 Mcal/kg of ME (DM basis). Blood samples were collected from the ewes at 62, 76, 90, 104, 118, 132, and 135 d of gestation. Fetal blood was collected at necropsy on d 135. In Exp.1, dietary Se source and concentration had no effect (P > 0.17) on maternal and fetal serum IGF-I, triiodothyronine (T(3)), or thyroxine (T(4)) concentrations. Selenium supplementation increased (P = 0.06) the T(4):T(3) ratio vs. controls. In Exp. 2, dietary Se had no impact (P > 0.33) on main effect means for maternal and fetal serum IGF-I, T(3), or T(4) concentrations from d 62 to 132; however, at d 135, high-Se ewes had lower (P = 0.01) serum T(4) concentrations than adequate-Se ewes. A nutrition by Se interaction (P = 0.06) was detected for the T(4):T(3) ratios; ewes fed restricted and adequate-Se diets had greater (P = 0.10) T(4):T(3) ratios compared with the other treatments. Nutrient-restricted ewes had lower (P < 0.05) serum IGF-I, T(3), and T(4) concentrations. Fetal serum IGF-I concentrations were lower (P = 0.01) in restricted-vs. control-fed ewes; however, fetal T(3) and T(4) concentrations were unaffected (P > 0.13) by dietary Se or maternal plane of nutrition. These data indicate that dietary Se may alter maternal T(4):T(3) ratios. In addition, nutrient restriction during gestation reduces maternal IGF-I, T(3), and T(4) and fetal IGF-I concentrations.     

Effects of time and dietary selenium concentration as sodium selenite on tissue selenium uptake by sheep

Thirty crossbred wethers (60 kg avg initial wt) were used to study the time-dose response to dietary Se as sodium selenite (Na2SeO3). Sheep were fed a basal diet (.20 mg/kg Se, M basis) for 10 d; three wethers were killed and tissues were collected for controls. The remaining 27 sheep were assigned randomly to diets supplemented with either 3, 6 or 9 mg/kg Se (as-fed basis) from reagent grade Na2SeO3 and fed for 10, 20 or 30 d. Feed offered was restricted to 1,200 g daily and tap water was available ad libitum. Sheep were stunned and killed by exsanguination and liver, kidney, muscle, heart and spleen were removed and frozen for Se analysis. No toxic effects were noted as expressed by feed intake or hemoglobin concentration. Added dietary Se increased Se linearly (P less than .01) in liver, kidney, and serum. Selenium in liver, kidney and serum also increased (P less than .01) as time advanced. Serum, liver and kidney were more sensitive to dietary Se than were muscle, heart and spleen. Ten days appeared to be an adequate length of time for further Se bioassay studies of this nature. Reagent grade Na2SeO3 was nontoxic when fed to sheep for 30 d at levels up to 90 times the Se requirement.     

Effect of dietary linoleic acid concentration and vitamin E supplementation on cell desquamation and susceptibility to oxidative damage of pig jejunal mucosa

Sixty Large White × Great York pigs weighing approximately 60 kg were individually fed on six experimental diets. The experiment was organized in a 3 × 2 factorial arrangement design with three different fat sources and a basal or supplemented (200 mg/kg diet) level of α-tocopheryl acetate. All diets contained the same concentration of saturated fatty acids (15 ± 0.2 g/kg dry matter) but differed in the concentration of C18 : 2 (14 ± 0.5, 18 ± 0.4 and 21 ± 0.6 g/kg) and monounsaturated fatty acids (19 ± 0.2, 15 ± 1.2 and 10 ± 1.3 g/kg). No effect of dietary treatment was observed on weight gain and feed consumption. A histological study of the jejunal mucosa showed lower cell desquamation in groups containing a supplemental level of α-tocopheryl acetate (p=0.080). A higher cell desquamation was found in the groups fed diets containing the higher concentration of C18 : 2 (p=0.087). We also observed an interaction effect (p < 0.001) of dietary fat source and vitamin E supplementation on jejunal cell desquamation in which the effect of dietary vitamin E was lower when diets with a low concentration of C18 : 2 were administered. In vitro- induced oxidation of jejunal mucosa homogenates was lower in pigs fed diets supplemented with α-tocopheryl acetate (p < 0.002). The dietary concentration of C18 : 2 significantly affected oxidation of pig jejunal mucosa (p < 0.002).     

Effects of dietary calcium:phosphorus ratios on apparent absorption of calcium and phosphorus in the small intestine, cecum, and colon of pigs

Thirty-two crossbred barrows were used to investigate the effects of dietary Ca:total P (tP) ratios in phytase-supplemented diets on the apparent absorption of P and Ca in the small intestine, cecum, and colon. Three Ca:tP ratio treatments (1.5:1, 1.3:1, or 1.0:1) were created by adjusting the amount of ground limestone added to the basal low-P grower (.39% tP including .07% added inorganic P) and finisher (.32% tP without added inorganic P) diets. All low-P ratio diets were supplemented with Natuphos phytase at 500 units/kg. A positive control diet without phytase supplementation contained adequate P and Ca to meet dietary requirements. At 123 kg, the pigs were slaughtered and the contents of ileum, cecum, and colon were collected. Lowering the dietary Ca:tP ratio in the diets containing phytase linearly increased (P < .01) the apparent absorption (% and g/d) of P in the small intestine, but Ca absorption was not affected. Pigs fed the low-P diet with a Ca:tP ratio of 1.0:1 had an apparent absorption (g/d) of P or Ca similar to that of pigs fed the control diet, which was adequate in Ca and P. Averaged across all diets, the apparent absorption of P was highest when measured at the cecum, and the apparent absorption of Ca was highest when measured at the colon. In conclusion, lowering the dietary Ca:tP ratio to 1.0:1 in a low-P diet containing phytase increased the apparent absorption of P in the small intestine. Furthermore, a significant amount of P was absorbed in the cecum.     

Association of maximum voluntary dietary intake of freeze-dried garlic with Heinz body anemia in horses

OBJECTIVE: To characterize hematologic and clinical consequences of chronic dietary consumption of freeze-dried garlic at maximum voluntary intake in horses. ANIMALS: 4 healthy sex- and age-matched horses. PROCEDURE: An initial garlic dose (0.05 g/kg, twice daily) was fed to 2 horses in a molasses carrier as part of their normal ration and was gradually increased to maximum voluntary intake (0.25 g/kg, twice daily) over 41 days. Dietary supplementation then continued for a total of 71 days. Two control horses were fed molasses with no garlic with their ration. Blood samples were collected weekly and analyzed for hematologic and biochemical changes, including the presence of Heinz bodies. Recovery of affected blood values was followed for 5 weeks after termination of dietary supplementation with garlic. RESULTS: At a daily dose of > 0.2 g/kg, horses fed garlic developed hematologic and biochemical indications of Heinz body anemia, as characterized by increases in Heinz body score (HBS), mean corpuscular volume (MCV), mean corpuscular hemoglobin, platelet count, and serum unconjugated and total bilirubin concentrations and decreases in RBC count, blood hemoglobin concentration, mean corpuscular hemoglobin concentration, and serum haptoglobin concentration. Recovery from anemia was largely complete within 5 weeks after termination of dietary supplementation with garlic. Heinz body score and MCV remained high at the end of the 5-week recovery period. CONCLUSIONS AND CLINICAL RELEVANCE: Horses will voluntarily consume sufficient quantities of garlic to cause Heinz body anemia. The potential for garlic toxicosis exists when horses are chronically fed garlic. Further study is required to determine the safe dietary dose of garlic in horses.     

Effect of dietary mannan oligosaccharides and(or) pharmacological additions of copper sulfate on growth performance and immunocompetence of weanling and growing/finishing pigs

Two experiments were conducted to determine the efficacy of mannan oligosaccharides (MOS) fed at two levels of Cu on growth and feed efficiency of weanling and growing-finishing pigs, as well as the effect on the immunocompetence of weanling pigs. In Exp. 1, 216 barrows (6 kg of BW and 18 d of age) were penned in groups of six (9 pens/treatment). Dietary treatments were arranged as a 2 x 2 factorial consisting of two levels of Cu (basal level or 175 ppm supplemental Cu) with and without MOS (0.2%). Diets were fed from d 0 to 38 after weaning. Blood samples were obtained to determine lymphocyte proliferation in vitro. From d 0 to 10, ADG, ADFI, and gain:feed (G:F) increased when MOS was added to diets containing the basal level of Cu, but decreased when MOS was added to diets containing 175 ppm supplemental Cu (interaction, P < 0.01, P < 0.10, and P < 0.05, respectively). Pigs fed diets containing 175 ppm Cu from d 10 to 24 and d 24 to 38 had greater (P < 0.05) ADG and ADFI than those fed the basal level of Cu regardless of MOS addition. Pigs fed diets containing MOS from d 24 to 38 had greater ADG (P < 0.05) and G:F (P < 0.10) than those fed diets devoid of MOS. Lymphocyte proliferation was not altered by dietary treatment. In Exp. 2, 144 pigs were divided into six pigs/pen (six pens/treatment). Dietary treatments were fed throughout the starter (20 to 32 kg BW), grower (32 to 68 kg BW), and finisher (68 to 106 kg BW) phases. Diets consisted of two levels of Cu (basal level or basal diet + 175 ppm in starter and grower diets and 125 ppm in finisher diets) with and without MOS (0.2% in starter, 0.1% in grower, and 0.05% in finisher). Pigs fed supplemental Cu had greater (P < 0.05) ADG and G:F during the starter and grower phases compared to pigs fed the basal level of Cu. During the finisher phase, ADG increased when pigs were fed MOS in diets containing the basal level of Cu, but decreased when MOS was added to diets supplemented with 125 ppm Cu (interaction, P < 0.05). Results from this study indicate the response of weanling pigs fed MOS in phase 1 varied with level of dietary Cu. However, in phase 2 and phase 3, diets containing either MOS or 175 ppm Cu resulted in improved performance. Pharmacological Cu addition improved gain and efficiency during the starter and grower phases in growing-finishing pigs, while ADG response to the addition of MOS during the finisher phase seems to be dependent upon the level of Cu supplementation.