The cadmium status of horses from central Europe depending on breed, sex, age and living area

The Cd status of animals is best reflected by kidneys and much worse by liver and hair. Breed (heavy- and warm-blooded horses) only took an insignificant effect on the Cd content of kidneys and liver. On the average, however, warm-blooded horses stored more Cd than heavy ones. Geldings from Cd-exposed living areas accumulated insignificantly more Cd in liver, kidneys and hair than mares. The influence of age on the Cd content of kidneys and liver of Cd-exposed horses was significant. The Cd exposure of a living area was very well reflected by kidneys and liver. On the average, horses from two areas with nonferrous metal smelting stored 1000 mg Cd/kg kidney dry matter and 100 to 200 mg Cd/kg liver dry matter. The highest Cd concentration of the kidneys of horses amounted to 2.6 and 2.3 g/kg dry matter, resp.     

The role of selenium in cadmium toxicity: interactions with essential and toxic elements

1. The study was part of a project designed to investigate if organic selenium (Se) can ameliorate the toxic effects of cadmium (Cd). The main objective of the present study was to investigate, in the chicken, the interactions between Se, Cd and the following elements: Sb, Ca, Cr, Co, Cu, Fe, Pb, Mg, Mn, Mo, Ni, V and Zn.

2. A total of 300 1-d-old chickens (broilers) were randomly distributed among 4 dietary treatments with 5 replicate pens per treatment. In T1, chickens were fed on a diet with 0·3?mg/kg added Se, without added Cd. In T2, chickens were fed on a diet with 0·3?mg/kg Se and 10?mg/kg Cd. In T3, chickens were fed on a diet with 0·3?mg/kg Se and 100?mg/kg of Cd added and in T4 treatment, chickens were fed on a diet with 3?mg/kg Se and 100?mg/kg Cd added. Se was added as Se-yeast. Cd was added as cadmium chloride (CdCl₂). On d 28 and 42, two chickens per replicate pen were killed for collection of whole blood, liver, kidney and breast muscle samples. Samples were analysed by ICP-MS. The data were analysed using a multivariate linear model.

3. While low Cd concentrations in the diet led only to an increase of Cd concentration in the examined tissues, addition of high concentrations of Cd increased the concentration of Cd, Cu, Sb and V and decreased that of Se, Mn and Fe. Addition of high Se concentrations did not significantly reduce Cd concentration.

4. Prior to model application, correlations of 78 elements were noted, while after model application 39 correlations were noted. Most notably, Cd was correlated with Ca, Co, Cu and Mg, while Se was correlated with Mn.

5. The present study revealed several correlations between essential, probably essential and toxic elements illustrating the importance of the balance between pro-oxidants and antioxidants.     

耐镉乳酸菌对蛋鸡组织和鸡蛋中镉残留及部分矿物元素沉积的影响

试验旨在探明耐镉乳酸菌对蛋鸡的脏器系数、镉在蛋鸡组织及鸡蛋中的残留及钙、铁、锌、锰、铜和硒在组织和鸡蛋中沉积的影响。试验分为5组：对照组,饲喂基础日粮;镉组,基础日粮+5 mg/kg镉（以氯化镉的形式添加）;乳酸菌组,基础日粮+1×10¹⁰ CFU/kg耐镉乳酸菌;镉+低剂量乳酸菌组,基础日粮+5 mg/kg镉+1×10¹⁰ CFU/kg耐镉乳酸菌;镉+高剂量乳酸菌组,基础日粮+5 mg/kg镉+1×10¹¹ CFU/kg耐镉乳酸菌,试验期6周。试验期末,采集各组蛋鸡血液,测定总抗氧化力（T-AOC）和超氧化物歧化酶（SOD）活力;采集各组蛋鸡内脏组织和鸡蛋,计算脏器系数,同时测定组织和鸡蛋中镉、钙、铁、铜、锌、锰及硒元素含量。结果显示,与对照组相比,镉及乳酸菌组显著提高了蛋鸡总抗氧化能力（P<0.05）。各处理组中,镉组脾脏指数最低,镉加乳酸菌组脾脏指数显著高于镉组（P<0.05）;与对照组相比,乳酸菌组显著提高心脏指数（P<0.05）。镉组致蛋鸡肝脏和肾脏中镉残留量远高于其他组织,补加耐镉乳酸菌显著减少了心脏的镉残留量（P<0.05）。与对照组相比,镉组显著降低肾脏钙、脾脏和卵黄的锰含量（P<0.05）;与对照组相比,镉加低剂量耐镉乳酸菌显著增加肾脏锰含量、卵黄铁含量及肾脏和脾脏铜含量（P<0.05）;镉在鸡蛋中的残留量较低,与对照组相比,镉组显著降低鸡蛋铁、锰元素含量（P<0.05）,补加耐镉乳酸菌显著增加铁、锌、锰和硒元素含量（P<0.05）。结果表明,在蛋鸡日粮中添加1×10¹⁰ CFU/kg的耐镉乳酸菌,可显著提高蛋鸡血清总抗氧化力水平和蛋鸡的心脏指数,显著改善镉暴露导致的脾脏萎缩和心脏镉的残留量;同时显著增加锰、铜、铁在肾脏、脾脏及卵黄中的含量及铁、锌、锰和硒在鸡蛋中的含量。     

Theophylline and dyphylline pharmacokinetics in the horse

The pharmacokinetics of theophylline and dyphylline were determined after IV administration in horses. In a preliminary experiment, the usual human dosage (milligram per kilogram) of each drug was given to 1 horse. Results were used to calculate dosages for a cross-over study, using 6 horses for each drug. Theophylline plasma concentrations decreased triexponentially in 5 of 6 healthy horses after IV infusion of 10 mg of aminophylline/kg of body weight for 16 to 32 minutes. In the 6 horses, total body elimination rate constants were variable, and the half-life of theophylline was 9.7 to 19.3 hours. Clearance was 42.3 to 69.2 ml/hr/kg. The initial distribution phase was rapid (t1/2 approx 3.5 to 4 minutes); a 2nd distribution phase was slower (t1/2 approx 1.5 to 2 hours). Plasma concentrations of theophylline were in the assumed effective range (10 to 20 micrograms/ml) from 15 minutes until 40 minutes after time zero. The mean apparent volume of distribution was 1.02 L/kg. After bolus IV injection of dyphylline (20 mg/kg), pharmacokinetics were best described by a 2-compartment open model in 2 horses and by a 3-compartment open model in 4 horses. In the 6 horses, elimination half-life of dyphylline was 1.9 to 2.9 hours, and clearance was 200 to 320 ml/hr/kg. Plasma concentrations (approx 50 micrograms/ml) were observed at 10 minutes after injection without adverse effects. Concentrations greater than 10 micrograms/ml were observed from time zero to about 1.5 hours after injection. Theophylline induced significant increases in heart rate, but dyphylline did not affect heart rate significantly.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immunomodulation in weanling swine with dietary selenium

The capability of dietary selenium (Se) to augment the immune response was evaluated in 96 crossbred weanling swine. Six groups of 16 pigs were fed diets with Se supplemented as sodium selenite at 0, 0.3, 0.6, 0.9, 1.2, and 1.5 mg/kg. The basal diet contained 0.068 mg of Se/kg. Weight gain, feed consumption, and feed efficiency were similar for all diets. Whole blood concentrations of Se linearly increased as the dietary concentrations of Se increased. The humoral response was monitored by immunoglobulin G titers to lysozyme and ribonuclease, using an enzyme-linked immunosorbent assay. Although no significant difference in immunoglobulin G titers to either antigen was detected among diets, a similar trend in antibody response was noted. The diet with 0.9 mg of added Se/kg produced the highest antibody response to both antigens, whereas the diet with 0.3 mg of added Se/kg produced the lowest titers for both antigens. Cell-mediated immunity was evaluated in the pigs by the dermal response to phytohemagglutinin. Significant difference was not detected in pigs fed the various diets in terms of the mean diameters of their dermal reactions to phytohemagglutinin injections. Although blood concentrations of Se were increased, rate and efficiency of weight gain and humoral and cell-mediated immunity were not significantly improved by adding 0.3 to 1.5 mg of Se/kg to diets.     

Concentrations of strontium,barium, cadmium,copper, zinc,manganese, chromium,antimony, selenium,and lead in the liver and kidneys of dogs according to age,gender, and the occurrence of chronic kidney disease

This study was conducted to measure the concentrations of strontium (Sr), barium (Ba), cadmium (Cd), copper (Cu), zinc (Zn), manganese (Mn), chromium (Cr), antimony (Sb), selenium (Se), and lead (Pb) in canine liver, renal cortex, and renal medulla, and the association of these concentrations with age, gender, and occurrence of chronic kidney disease (CKD). Tissues from 50 dogs were analyzed using inductively coupled plasma mass spectrometry. Cu, Zn, and Mn levels were highest in the liver followed by the renal cortex and renal medulla. The highest Sr, Cd, and Se concentrations were measured in the renal cortex while lower levels were found in the renal medulla and liver. Female dogs had higher tissue concentrations of Sr (liver and renal medulla), Cd (liver), Zn (liver and renal cortex), Cr (liver, renal cortex, and renal medulla), and Pb (liver) than male animals. Except for Mn and Sb, age-dependent variations were observed for all element concentrations in the canine tissues. Hepatic Cd and Cr concentrations were higher in dogs with CKD. In conclusion, the present results provide new knowledge about the storage of specific elements in canine liver and kidneys, and can be considered important reference data for diagnostic methods and further investigations.     

Pharmacokinetics and pharmacodynamics of enrofloxacin and a low dose of amikacin administered via regional intravenous limb perfusion in standing horses

OBJECTIVE: To evaluate the pharmacokinetic-pharmacodynamic parameters of enrofloxacin and a low dose of amikacin administered via regional IV limb perfusion (RILP) in standing horses. ANIMALS: 14 adult horses. PROCEDURES: Standing horses (7 horses/group) received either enrofloxacin (1.5 mg/kg) or amikacin (250 mg) via RILP (involving tourniquet application) in 1 forelimb. Samples of interstitial fluid (collected via implanted capillary ultrafiltration devices) from the bone marrow (BMIF) of the third metacarpal bone and overlying subcutaneous tissues (STIF), blood, and synovial fluid of the radiocarpal joint were collected prior to (time 0) and at intervals after tourniquet release for determination of drug concentrations. For pharmacokinetic-pharmacodynamic analyses, minimum inhibitory concentrations (MICs) of 16 microg/mL (amikacin) and 0.5 microg/mL (enrofloxacin) were applied. RESULTS: After RILP with enrofloxacin, 3 horses developed vasculitis. The highest synovial fluid concentrations of enrofloxacin and amikacin were detected at time 0; median values (range) were 13.22 microg/mL (0.254 to 167.9 microg/mL) and 26.2 microg/mL (5.78 to 50.0 microg/mL), respectively. Enrofloxacin concentrations exceeded MIC for approximately 24 hours in STIF and synovial fluid and for 36 hours in BMIF. After perfusion of amikacin, concentrations greater than the MIC were not detected in any samples. Effective therapeutic concentrations of enrofloxacin were attained in all samples. CONCLUSIONS AND CLINICAL RELEVANCE: In horses with orthopedic infections, RILP of enrofloxacin (1.5 mg/kg) should be considered as a treatment option. However, care must be taken during administration. A dose of amikacin > 250 mg is recommended to attain effective tissue concentrations via RILP in standing horses.     

Effect of selenium source and dose on selenium status of mature horses

This study was conducted to determine the effects of either dietary Se source or dose on the Se status of horses. Twenty-five mature horses were blocked by BW and randomly allocated to 1 of 5 dietary treatments that comprised the same basal diet that differed only in Se source or dose. Treatments were as follows: negative control (0.085 mg of Se/kg of DM), 3 different dietary concentrations of supplemental organic Se (Se yeast; 0.2, 0.3, and 0.4 mg of total Se/kg of DM), and positive control (0.3 mg of total Se/kg of DM) supplemented with Na selenite. Horses initially received the control diet (6 kg of grass hay and 3 kg of concentrate per horse daily) for 56 d to allow diet adaptation. After the period of diet adaptation, horses were offered their respective treatments for a continuous period of 112 d. Jugular venous blood samples were collected before the morning feed on d 0, 28, 56, 84, and 112. Whole blood and plasma were analyzed for total Se, glutathione peroxidase activity in whole blood (GPX-1) and plasma, and thyroid hormones (thyroxine and triiodothyronine) in plasma. The proportion of total Se as selenomethionine (SeMet) or selenocysteine in pooled whole blood and plasma samples was determined on d 0, 56, and 112. Data were analyzed as repeated measures. Total Se in blood and plasma and GPX-1 activity were greater in all supplemented horses (P < 0.001, except P < 0.01 for GPX-1 in horses supplemented with the least dose of Se yeast) with a linear dose effect of Se yeast for whole blood and plasma Se (P < 0.001) and a quadratic dose effect (P < 0.05) for whole blood GPX-1 activity. A plateau for total Se in plasma was achieved within 75 to 90 d, although this was not observed in blood total Se or GPX-1 activity. On d 84 and 112, horses supplemented with Se yeast showed greater total Se in blood (P < 0.05) compared with horses supplemented with Na selenite, and a source effect (P < 0.05) was observed in the relationship between total blood Se and GPX-1 activity. Selenocysteine (the predominant form of Se in whole blood and plasma) increased in all horses supplemented with Se. The SeMet content of whole blood and plasma increased in horses supplemented with Se yeast, but it was not observed in those supplemented with selenite. The rate of increase in SeMet over time was greater in whole blood (P < 0.05) and plasma (P = 0.10) with the Se yeast product. In conclusion, Se yeast was more effective than Na selenite in increasing total Se in blood, mainly as consequence of a greater increase of the proportion of Se comprised as SeMet, but it did not modify GPX-1 activity.     

Estimation of the relative biological availability of inorganic selenium sources for ruminants using tissue uptake of selenium

An experiment was conducted to estimate the relative bioavailability of inorganic Se sources based on tissue Se deposition following supplementation at high dietary levels. Twenty-eight crossbred wethers averaging 50 kg initial weight were assigned randomly to seven treatments that were fed for 10 d. The basal diet contained .18 mg/kg Se (DM basis). Dietary Se was added at 0, 3, 6 or 9 mg/kg as reagent grade sodium selenite (Na2SeO3) and 6 mg/kg from either calcium selenite (CaSeO3), Na2SeO3 + fumed amorphous carrier or sodium selenate (Na2SeO4). There were four sheep per treatment group, housed in individual, raised pens with slatted floors. Daily feed intake was restricted to 1,200 g and tap water was available ad libitum. The basal diet was fed for a 10-d adjustment period, then sheep were fed experimental diets for 10 d. At the termination of the experiment, blood samples were taken; sheep were stunned and killed, and livers and kidneys were removed and frozen for Se analysis. There was a linear (P less than .001) uptake of Se in liver, kidney and serum. The CaSeO3 and Na2SeO4 sources resulted in greater (P less than .05) Se concentrations in liver and kidney than did Na2SeO3, but these differences were not significant when the analyzed dietary Se concentrations were used as a covariate in the statistical model. Based on linear and multiple linear regression slopes and average increases in serum, liver and kidney Se concentrations, estimated relative bioavailability values corrected for analyzed dietary concentration, were 100, 101, 90 and 133 for Na2SeO3, CaSeO3, Na2SeO3 + carrier and Na2SeO4, respectively.     

Dietary selenate versus selenite for cattle, sheep, and horses.

Food and Drug Administration regulations currently permit addition of .3 mg of Se per kilogram of diet for chickens, turkeys, ducks, swine, sheep, and cattle. However, field reports indicate that this level may not be adequate for ruminants in all situations. Because sodium selenite is the most common supplemental form and is known to be readily absorbed to particles or reduced to insoluble elemental Se or selenides in acid, anaerobic environments, studies were conducted with dairy cattle, sheep, and horses fed sodium selenate to determine whether Se from this source was more bioavailable than Se from sodium selenite. A 2-wk period of no Se supplementation was followed by 49 or 56 d of Se supplementation at .3 mg/kg of dietary DM. Serum Se concentrations and glutathione peroxidase (GSHPx) activities measured initially and periodically thereafter revealed no difference between Se forms in sheep and horses and only a small (P less than .05) advantage for selenate in supporting serum Se concentration in dairy cattle. Selenium concentrations in skeletal muscle and liver of sheep were not different between Se forms. Serum Se, but not GSHPx, increased with time, and .3 mg of supplemental Se per kilogram of dietary DM from either sodium selenate or sodium selenite supported normal serum Se concentrations in sheep, dairy cattle, and horses.     

Assessment of the influence of dietary vitamin E on sows and offspring in three parities: reproductive performance, tissue tocopherol, and effects on progeny

Sixty crossbred (Yorkshire-Hampshire X Duroc) gilts were fed one of four corn-soybean meal diets fortified with .3 ppm Se and 0, 16, 33, or 66 IU of DL-alpha-tocopheryl acetate/kg. The study was conducted over a three-parity period to evaluate sow reproductive performance and the vitamin E tissue status of both sows and progeny at various time periods postcoitum and(or) postpartum. The basal diet averaged 8.4 mg of alpha-tocopherol/kg and .38 ppm of Se. Although litter size at birth was lowest (P less than .15) when sows were fed the basal diet, a higher incidence of agalactia when sows were fed the lower dietary vitamin E levels resulted in an increased (P less than .05) litter size at 7 d postpartum as dietary vitamin E increased. Sow serum alpha-tocopherol increased (P less than .01) at each measurement period as dietary vitamin E level increased. Colostrum and milk alpha-tocopherol concentrations increased (P less than .01) as dietary vitamin E level increased, and colostrum values were three to five times higher than at later milks. Colostrum alpha-tocopherol declined by parity from sows fed less than or equal to 16 IU/kg but was similar at each parity for sows fed greater than or equal to 33 IU/kg, resulting in a dietary vitamin E x parity interaction (P less than .01). The Se content of sow milk declined with parity but was not affected by dietary vitamin E level. Sow liver tocopherol at weaning (28 d postpartum) increased (P less than .01) as dietary vitamin E increased and increased with parity (P less than .05). Pig serum and liver alpha-tocopherol concentrations were elevated at birth and 7 and 28 d of age as sow dietary level of vitamin E increased. Upon weaning, pigs were fed a torula yeast-dextrose diet that contained 3.0 mg of alpha-tocopherol/kg and .32 ppm Se for a 28-d postweaning period. Liver and serum alpha-tocopherol concentrations declined during the postweaning period. Evidence of the vitamin E deficiency occurred at 28 d postweaning in the progeny from sows fed the basal diet or 16 IU of vitamin E; the incidence was more prevalent in the pigs from Parities II and III. These results suggest that a supplemental level of 16 IU of vitamin E/kg of diet was inadequate for the reproducing sow; higher levels are justified, particularly when females are retained in the herd for several parities.     

Blood selenium in naturally fed horses and the effect of selenium administration

Blood Se of adult horses was 26.1, 25.8, and 27.0 ng/ml (mean values at 3 farms), where the Se of food was about 20 ng/g dry substance. Experimental adult horses which received about 41 ng Se/g food showed 45.3 ng/ml blood.At low Se intake suckling foals show higher blood Se than mares, but with high Se intake, the opposite will occur. This is reflected in milk Se, which raises but slowly with rise of mare’s blood Se.Se in blood plasma and in blood corpuscles is on the same level. The effect of various dose levels of Se on blood Se was studied: From 1.5 to 6 mg Se/week, blood Se rose rather linearity; 18 and 30 rag Se/week gave but slightly more effect than 6 mg.     

The effect of injectable barium selenate on the selenium status of horses on pasture

AIM: To examine the effect of intramuscular barium selenate on the blood selenium concentration of horses with marginal selenium status. METHODS: Eighteen mares were assigned to one of six groups. The mares in groups 1-4 received barium selenate at 0.5, 0.75, 1.0 and 1.5 mg Se/kg, respectively, injected into the right pectoral muscle mass. The mares in group 5 received sodium selenate at 0.05 mg Se/kg orally at 8-week intervals. The mares in group 6 were left untreated. Blood samples were collected at 0, 1, 2, 5, 10, 30, 60, 90, 120, 180, 240, 300 and 360 days after the initial treatment for assay of whole blood and plasma selenium. Injection site reactions were recorded on each sampling date. RESULTS: Treatment with barium selenate at each dose rate significantly increased whole blood, plasma and blood cell selenium concentrations when compared to no treatment or oral treatment with sodium selenate, and maintained group mean whole blood selenium concentrations in the adequate range (>1600 nmol/l) until the end of the experimental period of 1 year. The severity of injection site reactions increased with dose rate but was considered acceptable alt the lower dose rates used. CONCLUSION: The injection of barium selenate placed aseptically at a deep intramuscular site was efficacious in correcting the selenium status of mares grazing pasture with a selenium content of 0.01-0.07 mg/kg DM. However, some swelling and fibrosis at the injection site was apparent at all dose rates used. CLINICAL RELEVANCE: There is currently no long-acting selenium supplementation product licensed in New Zealand for use in horses. Barium selenate promises to provide a useful method for selenium supplementation for horses, with an effective duration of at least 1 year following a single injection.     

Tolerance of inorganic selenium by range-type ewes during gestation and lactation

The objectives of this 72-wk study were to evaluate and compare the effects of 6 dietary levels of inorganic Se on serum, whole blood, wool, and tissue Se concentrations and to determine the maximum tolerable level of Se for mature ewes during lamb production. Forty-one, 4-yr-old, range-type ewes (57.4 +/- 5.7 kg) were used in a completely randomized design with 6 dietary treatments. Sodium selenite was added to a corn and soybean meal-based diet to provide 0.2 (control), 4, 8, 12, 16, or 20 mg of dietary Se/kg to ewes during lamb production. Serum Se and ewe BW were measured at 4-wk intervals; whole blood Se and wool Se were measured every 12 wk; and samples of brain, diaphragm, heart, hoof, kidney, liver, and psoas major were collected at the termination of the experiment. Dietary Se did not affect ewe BW during the study (P = 0.69), and there was no treatment x time interaction. Serum Se increased linearly as dietary Se level increased (P < 0.001) and responded cubically (P = 0.02) over time. Selenium in whole blood increased linearly (P < 0.001) as supplemental Se increased. Wool Se increased linearly (P < 0.001) as dietary Se increased, and the response over time was quadratic (P < 0.001). Brain, diaphragm, heart, and psoas major Se increased (P < 0.05) linearly as dietary Se increased, liver Se responded quadratically (P < 0.05), and hoof and kidney Se increased cubicically (P < 0.05) as supplemental Se increased. In general, serum, whole blood, and tissue Se concentrations of ewes receiving 12, 16, or 20 mg of dietary Se/kg were greater (P < 0.05) than those of controls and ewes receiving less dietary Se. Although they were elevated in ewes receiving increased dietary Se, at no time did serum, whole blood, or wool Se concentrations reach levels previously reported as toxic, nor were clinical signs of Se toxicosis observed. Histopathological evaluation of liver, kidney, diaphragm, heart, and psoas major did not reveal evidence of Se toxicosis in ewes at any dietary Se level. Ewes under our experimental conditions and during the stresses of production were able to tolerate up to 20 mg of dietary Se/kg as sodium selenite for 72 wk. These findings suggest that the maximum tolerable level of inorganic Se for sheep is much greater than 2 mg/kg as was suggested previously. Experiments of longer duration and utilizing greater dietary Se concentrations are necessary to clearly define the maximum tolerable level.     

Effect of selenium supplementation and source on the selenium status of horses

This study was conducted to determine the effect of Se supplementation and source on the Se status of horses. Eighteen 18-mo-old nonexercised horses were randomly assigned within sex to 1 of 3 treatments: 1) control (CTRL, no supplemental Se, 0.15 mg of Se/kg of total diet DM); 2) inorganic Se (INORG, CTRL + 0.45 mg of Se/kg of total diet DM from NaSeO3); or organic Se [ORG, CTRL + 0.45 mg of Se/kg of total diet DM from zinc-L-selenomethionine (Availa Se, Zinpro, Corp., Eden Prairie, MN)]. Horses were acclimated to the CTRL diet (7.1 kg of DM alfalfa hay and 1.2 kg of DM concentrate per horse daily) for 28 d. After the acclimation period, the appropriate treatment was top-dressed on the individually fed concentrate for 56 d. Jugular venous blood samples were collected on d 0, 28, and 56. Middle gluteal muscle biopsies were collected on d 0 and 56. Muscle and plasma were analyzed for Se concentrations. Glutathione peroxidase activity was measured in muscle (M GPx-1), plasma (P GPx-3), and red blood cells (RBC GPx-1). Data were analyzed as a repeated measures design. Mean plasma Se concentration on d 28 and 56 was greater (P < 0.05) for Se-supplemented horses compared with CTRL horses, and tended (P < 0.1) to be greater in ORG vs. INORG on d 28. Mean muscle Se concentration and P GPx-3 activities increased (P < 0.05) from d 0 to 56 but were not affected by treatment. Mean RBC GPx-1 activity tended to be greater (P < 0.1) in ORG than INORG or CTRL horses on d 28, and tended to be greater (P < 0.1) for INORG compared with ORG horses on d 56. Mean RBC GPx-1 activity of INORG and ORG horses was not different from that of CTRL on d 56. Mean M GPx-1 activity decreased (P < 0.01) from d 0 to 56. In conclusion, zinc-L-selenomethionine was more effective than NaSeO3 at increasing plasma Se concentration from d 0 to 28; however, both supplemental Se sources had a similar effect by d 56. No difference in Se status due to Se supplementation or source could be detected over a 56-d supplementation period by monitoring middle gluteal muscle Se, M GPx-1, or P GPx-3. Results for RBC GPx-1 also were inconclusive relative to the effect of Se supplementation and source.     

Spinal fluid concentrations of mepivacaine in horses and procaine in cows after thoracolumbar subarachnoid analgesia

The CSF concentrations of mepivacaine in 10 Standardbred horses and of procaine in 10 Holstein cows given the drugs by thoracolumbar subarachnoid injection were determined. Mepivacaine hydrochloride was injected into the horses (502 +/- 60.5 kg) at an average dosage of 30 mg (1.5 ml of 20 mg/ml solution). Analgesia was produced 7.5 +/- 4.3 minutes after injection, extended between spinal cord segments T13 and L3 on both sides of the spinal column, and lasted 47 +/- 18.7 minutes at the T18 dermatome. Procaine hydrochloride was injected into cows (614 +/- 51.5 kg) at a dosage ranging between 75 mg and 100 mg (1.5 ml and 2 ml of 50 mg/ml solution). Analgesia was produced 8.2 +/- 2.0 minutes after injection, extended between spinal cord segments T11 and L4 on both sides of the spinal column, and lasted 47 +/- 17.5 minutes at the T13 dermatome. The critical CSF concentrations of local anesthetics required to eliminate response to pinprick stimulation were 204.4 +/- 90.3 micrograms of mepivacaine/ml in horses and 197.0 +/- 86.1 micrograms of procaine/ml in cows. Average CSF concentrations at 120 minutes after injections were made were 16.8 +/- 15.5 micrograms of mepivacaine/ml and 30.6 +/- 17.1 micrograms of procaine/ml. In in vitro experiments to determine the rates of hydrolysis of mepivacaine and procaine in CSF, significant changes (P greater than 0.05) were not seen in the CSF concentrations of mepivacaine in horses and procaine in cattle after a 120-minute incubation (37 C). The analgesic threshold concentrations of mepivacaine in CSF of horses and procaine in CSF of cows were similar.(ABSTRACT TRUNCATED AT 250 WORDS)     

Determination of optimal dietary selenium levels by full expression of selenoproteins in various tissues of broilers from 22 to 42 d of age

The current NRC dietary selenium (Se) requirement (0.15 mg/kg) of broilers from 22 to 42 d of age is primarily based on a previous study reported in 1986, which might not be applicable to modern classes of rapidly growing broilers. The present experiment was conducted to determine the optimal dietary Se level for meeting metabolic and functional Se requirements of broilers fed a corn-soybean meal diet from22 to 42 d of age. A total of 336 Arbor Acres male broilers at 22 d old were randomly assig...     

Copper, zinc and manganese concentrations in equine liver, kidney and plasma

Five groups of horses were fed different diets of known trace mineral concentration for a minimum of six months. Copper (Cu), zinc (Zn) and manganese (Mn) concentrations were measured in livers of 125 yearling horses and kidneys of 81 yearling horses as an assessment of trace mineral status. Plasma Cu and Zn determinations were made for all horses.

Mean hepatic Cu concentrations of horses fed diets containing 6.9 to 15.2 mg Cu/kg dry matter (DM) feed were 0.27 to 0.33 μmol/g DM tissue. Plasma Cu concentrations ranged between 22.8 to 28.3 μmol/L. There was no simple mathematical relationship between plasma and hepatic Cu concentrations. Mean hepatic Zn concentrations in horses fed diets containing 25.6 to 52.2 mg Zn/kg DM feed were determined to be between 2.75 to 2.91 μmol/g DM tissue. Mean plasma Zn concentrations in groups of horses were between 11.7 to 13.5 μmol/L. Plasma Zn concentrations were not indicative of hepatic Zn concentration. Hepatic Mn concentrations ranged between 0.13 and 0.14 μmol/g DM tissue.

Renal Zn concentrations ranged between 1.55 to 1.63 μmol/g DM tissue and did not differ with diet. Mean renal Mn concentrations were 0.09 μmol/g DM tissue for all groups of horses. Renal Cu concentrations ranged from 0.36 to 0.47 μmol/g DM tissue and differed with diet.

     

The influence of dietary selenium levels on blood levels of selenium and glutathione peroxidase activity in the horse

Twenty mature geldings, averaging 535 kg, were used to determine the influence of dietary selenium (Se) on the blood levels of Se and Se-dependent glutathione peroxidase (SeGSH-Px) activity in the horse. Horses were randomly assigned within breed to four treatments consisting of five horses each and fed a basal diet containing .06 ppm of naturally occurring Se. Diets were supplemented with .05, .10 and .20 ppm Se, as sodium selenite. Blood was drawn for 2 wk before, and for 12 wk following, the inclusion of supplement Se in the diets. Whole blood and plasma Se concentrations and plasma SeGSH-Px activities were determined from all blood samples. Selenium concentrations in plasma and whole blood increased linearly from wk 1 to wk 5 and 6, respectively, in Se-supplemented horses. After these times, no significant changes in Se concentration were observed in Se-supplemented or in unsupplemented horses throughout the remainder of the 12-wk trial. Plasma Se reached plateaus of .10 to .11, .12 to .14, and .13 to .14 micrograms/ml in horses supplemented with .05, .10 and .20 ppm Se, respectively. Whole blood Se reached plateaus of .16 to .18, .19 to .21, and .17 to .18 micrograms/ml in horses supplemented with .05, .10 and .20 ppm Se, respectively. Plasma SeGSH-Px activity was not significantly affected by dietary treatment. Therefore, this enzyme was not a good indicator of dietary Se in these mature horses.     

蛋氨酸铜对西门塔尔牛发情周期生殖激素分泌的影响

选用16头18月龄,体况良好,体重380±26 kg的西门塔尔牛育成母牛,采用完全随机区组设计分为4组,以蛋氨酸铜为铜源,研究日粮加铜(0、8、16和24 mg/kg)对发情周期生殖激素分泌规律的影响。结果表明:8 mg/kg组和16 mg/kg组显著提高了发情周期LH、FSH、P4和E2水平(P<0.05);24 mg/kg组有所提高,但不显著(P>0.05)。说明添加蛋氨酸铜8~16 mg/kg对发情周期生殖激素分泌有显著促进作用。考虑基础日粮的含铜量,建议日粮铜水平为:13.87~21.87 mg/kg。