Plasma Zn Concentrations Research Articles

Bioavailability of zinc from zinc sulfate and different organic zinc sources and their effects on ruminal volatile fatty acid proportions

Twenty-four Angus steers were used to determine the effects of dietary zinc (Zn) level and source on Zn metabolism and ruminal volatile fatty acid (VFA) patterns. All steers were fed a low Zn diet (18.8 mg Zn per kg) for 42 days prior to assignment to dietary treatments. Treatments consisted of: (1) control (low Zn diet), (2) Zn sulfate (ZnSO 4), (3) Zn methionine complex (ZnMet) and (4) Zn glycine complex (ZnGly). The Zn sources were added to provide 20 mg of supplemental Zn per kg diet. A 5-day total collection of feces and urine was conducted beginning on day 14 of the study. Liver biopsy samples were obtained on days 0 and 42 for Zn analysis, and ruminal fluid was collected on day 42 for VFA and ruminal soluble Zn determination. Plasma samples were obtained on days 0, 2, 19, 21, and 42 for determination of plasma Zn and alkaline phosphatase activity. Urinary excretion of Zn was higher ( P<0.05) in steers supplemented with ZnMet or ZnGly than in controls. Apparent absorption and retention of Zn were not significantly affected by treatment, but tended to be higher in steers receiving ZnGly. Liver Zn concentrations were higher ( P<0.05) on day 42 in steers supplemented with ZnGly, compared to steers receiving control, ZnMet or ZnSO 4 treatments. Plasma Zn concentrations were higher ( P<0.05) for the ZnGly and ZnMet treatments compared to the control on day 42. Plasma alkaline phosphatase was not affected by treatment. Ruminal soluble Zn concentrations were higher ( P<0.05) in steers fed ZnMet compared to those fed the control or ZnSO 4 diets. Total VFA concentrations were higher ( P<0.05) in steers fed the control and ZnSO 4 treatments than in those receiving ZnGly or ZnMet. Steers supplemented with ZnMet had a higher ( P<0.05) molar proportion of propionate and lower ( P<0.05) molar proportions of butyrate and valerate than controls. Compared to the control treatment, valerate was the only VFA affected by ZnSO 4 or ZnGly supplementation. Results suggest that Zn from ZnGly was more bioavailable than ZnSO 4 or ZnMet. However, ZnMet supplementation resulted in the highest ruminal soluble Zn concentrations and altered ruminal VFA proportions to the greatest extent of the Zn sources evaluated.

Effect of dietary trace mineral concentration and source (inorganic vs. chelated) on performance, mineral status, and fecal mineral excretion in pigs from weaning through finishing.

Two hundred and sixteen weanling gilts (6.65+/-0.08 kg) were used to determine the effects of decreasing supplemental concentrations of Zn, Cu, Fe, and Mn, and trace mineral source (inorganic vs. chelated) on growth performance, mineral status, and fecal mineral concentrations from weaning through development. The study was conducted over three trials with 72 pigs in each trial. Gilts were blocked by weight and randomly assigned to either 1) control, 2) reduced inorganic, or 3) reduced chelated trace minerals. The control diet was supplemented with 25, 150, 180, and 60 mg/kg of Cu, Zn, Fe, and Mn (in sulfate forms), respectively, during the nursery phase and 15, 100, 100, and 40 mg/kg of supplemental Cu, Zn, Fe, and Mn, respectively, during the growing and gilt-developer phases. Reduced inorganic and reduced chelated treatments were supplemented during all phases with 5, 25, 25, and 10 mg/kg of Cu, Zn, Fe, and Mn, respectively. The reduced chelated treatment supplied 50% of the supplemental Cu, Zn, Fe, and Mn in the form of metal proteinates, with the remainder from sulfate forms. Performance by control pigs did not differ from pigs fed the reduced trace mineral treatments during the nursery and grower-development periods. Gain:feed was lower (P < 0.05) for pigs fed the reduced inorganic compared with those fed the reduced chelated treatment during the nursery period. Trace mineral source did not affect performance during the growing or gilt-developer phase. Plasma Zn concentration and alkaline phosphatase activity were higher (P < 0.01) in control pigs than in those receiving reduced trace minerals during the nursery and growing phases. Plasma Cu concentration and ceruloplasmin activity were generally not affected by treatment. Hemoglobin concentrations were lower (P < 0.05) for the reduced inorganic compared with the reduced chelated treatment in the nursery phase. Fecal concentrations of Cu, Zn, and Mn were lower (P < 0.05) in pigs fed reduced trace minerals than in controls during all production phases. Fecal Zn concentration during the nursery and fecal Cu concentrations during the growing and gilt-developer phases were lower (P < 0.05) in pigs fed the reduced chelated compared with the reduced inorganic treatment. Results indicate that reducing the concentrations of Zn, Cu, Mn, and Fe typically supplemented to pig diets will greatly decrease fecal mineral excretion without negatively affecting pig performance from weaning through development.

Effect of zinc supplemented as either an organic or an inorganic source and of microbial phytase on zinc and other minerals utilisation by weanling pigs

Thirty-six pigs, weaned at 28 days of age at an average body weight of 9.3 kg were used in a 19-day experiment to assess the bioavailability of Zn. A Zn–methionine complex with a molar methionine to Zn ratio of 2:1 was compared to Zn sulphate using a basal diet based on maize and soya bean meal supplemented with or without microbial phytase. Six experimental diets were formulated: the basal diet containing 32 mg Zn/kg, the basal diet supplemented with 20 mg Zn/kg from either sulphate (ZnSO 4·7H 2O) or the organic source (ZnOrg), and the same three previous diets supplemented with 1200 units (U) of microbial phytase per kilogram. The replacement of ZnSO 4 by the organic source did not modify Zn retention, the concentration of Zn in bone and plasma or plasma alkaline phosphatase (AP) activity. The addition of microbial phytase considerably improved Zn bioavailability. Considering plasma AP activity, plasma Zn concentration, bone Zn concentration and Zn retention, the effect of adding 1200 U phytase/kg in the basal diet largely exceeded the effect of adding 20 mg Zn/kg. When phytase was added to the basal diet, these indicators of Zn status increased by 198, 269, 111 and 189%, respectively. Dietary phytase and Zn also modified the utilisation of Ca, P, Mg, Fe and Cu by piglets.

Maternal Zinc Deficiency Raises Plasma Prolactin Levels in Lactating Rats

There is an inverse relation between zinc (Zn) intake and plasma prolactin in men and nonpregnant women. Whether a relation exists in lactating women is unknown, despite the potential consequences of perturbations in prolactin regulation on lactation performance. We examined the effects of low Zn intake on prolactin concentration, the prolactin regulatory pathway in the pituitary gland, and lactation performance in lactating rats. Female rats were fed diets containing 7 (zinc deficient; ZD), 10 (marginally zinc deficient; MZD) or 25 mg Zn/kg (control) from 70 d preconception to lactation d 11. Rats were killed, pituitary glands dissected, and tissues and plasma collected and analyzed for prolactin concentration. Pituitary gland pituitary factor 1 (Pit-1), dopamine 2 receptor (D2R), and prolactin receptor mRNA expression were measured in the pituitary gland. Liver, mammary gland, plasma, and milk Zn were measured. Milk intake of the pups was also recorded. Plasma prolactin concentration was higher in rats fed the ZD (125.9 microg/L) diet compared with control rats (21.7 microg/L). Pituitary gland prolactin concentration was higher in rats fed the ZD diet (69.8 mg/g total protein) compared with controls (29.0 mg/g). Plasma Zn concentration was lower in rats fed the MZD and ZD diets, and mammary gland and milk Zn concentrations were lower in rats fed the ZD diet compared with control rats. Rats fed the ZD diet had lower D2R, prolactin receptor, and Pit-1 mRNA levels, whereas rats fed the MZD diet had lower prolactin receptor and Pit-1 mRNA levels compared with control rats. Milk intake was lower in pups of rats fed the MZD and ZD diets. Our results suggest that marginal Zn nutriture may compromise milk production despite increased prolactin levels. In addition, increased circulating prolactin concentration is not due to altered nursing behavior, but may be due to alterations in the prolactin regulatory pathway in the pituitary gland.

Relationship between pre-pregnancy BMI and plasma zinc concentrations in early pregnancy.

We previously reported that pregnant women whose plasma Zn concentrations were below the 50th percentile tended to have high pre-pregnancy BMI (kg/m(2)) values. We therefore hypothesized that in pregnant women, plasma Zn concentrations are negatively correlated with BMI. We evaluated the association between BMI values and plasma Zn concentrations in 1474 women whose blood samples were obtained before 15 weeks of gestation. Their mean age was 22.7 years and mean gestational age at blood sampling was 10 weeks. The mean plasma Zn concentration and BMI were 11.6 micromol/l and 26.6 kg/m(2) respectively. Because plasma Zn concentrations decrease as gestational age increases, plasma Zn concentrations were standardized by Z-scores. Z-score distributions were compared among the quartiles of BMI. The highest BMI group had the lowest plasma Zn concentrations, whereas the lowest BMI group had the highest; the differences were significant between the BMI groups (P<0.0001). The interpretation of plasma Zn concentrations to assess Zn nutriture in pregnancy may be complicated not only by the well-established factor of gestational age at blood sampling, but also by a previously unrecognized factor, maternal BMI.

Large doses of zinc oxide increases the activity of hydrolases in rats

The effect of pharmacological doses of zinc oxide (1000; 2500; 5000 mg per kg diet) and two levels of dietary protein on pancreatic and intestinal hydrolase activity in rats were studied. It was hypothesized that ZnO would increase intestinal and pancreatic hydrolase enzyme activity. Male Wistar rats, averaging 64 g body weight, were randomly allocated to dietary treatments (chow diets- meeting all NRC requirements) containing 10% or 15% protein supplemented with additional ZnO (above 100 mg/kg ZnSO 4) as follows: 0.0; 0.1; 0.25; 0.5% w/w. Water and food were provided ad libitum. Animals were fed the diets for 10 days and body weights were recorded; after decapitation blood and organ samples were collected. Amylase, lipase, trypsin, and total protease activity of pancreatic homogenates and small intestinal contents were determined. ZnO supplementation dose dependently increased the plasma Zn concentration and significantly increased amylase, lipase, trypsin and total protease activity in pancreatic homogenates and small intestinal contents. The statistical analysis showed significant protein and ZnO interaction on the activity of amylase in the pancreas, and amylase, trypsin and total-protease in the small intestinal content. Therefore ZnO at high dietary concentration may influence the digestion of nutrients via increased hydrolase activity.

Clinical evaluation of the oral iron chelator deferiprone for the potential treatment of iron overload in bird species.

The clinical use of oral Fe chelators for the treatment of Fe-storage disease in birds requires evaluation. In this study, the efficacy of the Fe chelator deferiprone in reducing hepatic Fe stores, its effects on hematologic, biochemical, and plasma Fe parameters, and its potential toxicity during a 30-day treatment period were investigated in a controlled setting using two model species, the white leghorn chicken (Gallus gallus f. domestica) and the domestic pigeon (Columba livia). A second phase of the study investigated deferiprone-related Fe elimination in the excreta. Deferiprone, administered orally at a dosage of 50 mg/kg twice daily to birds that had been experimentally Fe loaded, significantly reduced hepatic Fe concentrations compared with levels in Fe-loaded and non-Fe-loaded controls. There were no significant alterations in routine clinical hematologic or biochemical parameters, although decreased transferrin saturation was noted in both species. Side effects associated with deferiprone administration were decreased weight gain and significant decreases in plasma Zn concentrations. No mortalities occurred in the pigeons, but there were three deaths in the deferiprone-treated group of Fe-loaded chickens, most likely associated with acute reduction of Fe required for normal enzymatic processes. Histologic changes associated with deferiprone treatment were not noted. Deferiprone caused a dose-dependent increase of Fe in the excreta at oral dosages of 50 and 75 mg/kg once daily in both species. Deferiprone is a promising, orally active Fe chelator for the treatment of Fe overload in birds, although its potential side effects need to be considered.

Alterations in Plasma Essential Trace Elements Selenium, Manganese, Zinc, Copper, and Iron Concentrations and the Possible Role of these Elements on Oxidative Status in Patients with Childhood Asthma

The aim of the present study is to evaluate the status of plasma essential trace element selenium (Se), manganese (Mn), copper (Cu), zinc (Zn), and iron (Fe) concentrations and the effect of these elements on oxidative status in patients with childhood asthma. Plasma Se, Mn, Cu, and Zn concentrations were determined by atomic absorption spectrophotometry (AAS) and Fe concentrations, malondialdehyde (MDA), and total antioxidant capacity (TAC) were determined by the colorimetric method. The plasma MDA/TAC ratio was calculated as an index of oxidative status. Plasma albumin levels were measured to determine nutritional status. Plasma Fe concentrations, MDA levels and the MDA/TAC ratio were significantly higher (p<0.001, p<0.001, and p<0.01, respectively) and Se and Mn concentrations and TAC were lower (p<0.01, p<0.05, and p<0.01, respectively) in patients when compared to the healthy subjects. Plasma Zn, Cu, and albumin levels were not found to be significantly different in patients and controls (p>0.05). There were positive relationships between plasma MDA and Fe (r=0.545, p<0.001) and TAC and Se (r= 0.485, p<0.021), and a negative correlation between TAC and MDA values (r= -0.337, p<0.031) in patients with childhood asthma. However, there was no correlation between these trace elements and albumin content in patient groups. These observations suggest that increased Fe and decreased Se concentrations in patients with childhood asthma may be responsible for the oxidant/antioxidant imbalance.

Association between plasma zinc concentration and zinc kinetic parameters in premenopausal women.

The objective of this study was to measure relationships between plasma zinc (Zn) concentrations and Zn kinetic parameters and to measure relationships of Zn status with taste acuity, food frequency, and hair Zn in humans. The subjects were 33 premenopausal women not taking oral contraceptives and dietary supplements containing iron and Zn. Main outcomes were plasma Zn concentrations, Zn kinetic parameters based on the three-compartment mammillary model using 67Zn as a tracer, electrical taste detection thresholds, and food frequencies. Lower plasma Zn was significantly (P < 0.01) associated with smaller sizes of the central and the lesser peripheral Zn pools, faster disappearance of tracer from plasma, and higher transfer rate constants from the lesser peripheral pool to the central pool and from the central pool to the greater peripheral pool. The break points in the plasma Zn-Zn kinetics relationship were found between 9.94 and 11.5 micromol/l plasma Zn. Smaller size of the lesser peripheral pool was associated with lower frequency of beef consumption and higher frequency of bran breakfast cereal consumption. Hypozincemic women with plasma Zn <10.7 micromol/l or 700 ng/ml had decreased thresholds of electrical stimulation for gustatory nerves. Our results based on Zn kinetics support the conventional cutoff value of plasma Zn (10.7 micromol/l or 700 ng/ml) between normal and low Zn status.

Marginal Maternal Zn Intake in Rats Alters Mammary Gland Cu Transporter Levels and Milk Cu Concentration and Affects Neonatal Cu Metabolism

Marginal zinc intake is common and leaves women particularly vulnerable to Zn deficiency due to increased demand for Zn as a consequence of reproduction. Zn deficiency during pregnancy and lactation has been associated with secondary affects on copper metabolism in the offspring; however, the underlying mechanisms are unknown. The effects of marginal maternal Zn intake on maternal and neonatal Cu metabolism were determined in rats. Plasma, milk and tissue Cu and Zn concentrations and plasma and milk ceruloplasmin (Cp) activity were measured in dams fed a control (CON, 25 mg Zn/kg diet) or a marginal Zn diet (ZD, 10 mg Zn/kg diet) and their suckling pups. There was no effect on maternal tissue Cu or Zn or milk Zn concentration; however, plasma Cp activity was higher in dams fed ZD, suggesting that Cp activity may be a useful marker for identifying marginal Zn status. Rats fed ZD had high mammary gland Ctr1, Atp7A and Atp7B levels, milk Cp activity and Cu concentration. Immunostaining and differential centrifugation indicated that ZD also altered Ctr1 and Atp7A localization in the mammary gland. Pups from dams fed ZD had higher small intestine Cu and lower plasma Cu than CON pups. These results suggest that marginal maternal Zn intake during pregnancy and lactation increase mammary gland Cu transporter levels and alter their localization, resulting in high milk Cu levels, possibly in response to transiently elevated plasma Cu levels. The combination of high milk Cu concentration and immature neonatal Cu transport exposes the suckling neonate to excess Cu; however, whether this occurs in humans is not yet known.

Role of Dietary Copper in Enhancing Resistance to Escherichia coli Mastitis

The role of dietary copper in enhancing resistance to Escherichia coli mastitis was investigated in first-lactation heifers. Twenty-three primigravid Holstein heifers were maintained on a basal (6.5ppm copper; −Cu) diet or a diet supplemented (20ppm) with copper sulfate (+Cu) beginning 60 d prepartum through 42 d of lactation. Liver biopsies and blood samples were taken for liver and blood minerals and plasma ceruloplasmin. Milk samples were taken weekly postpartum for bacteriology. The overall mean liver Cu concentration was about threefold higher, and the overall mean plasma Cu concentration was greater in the +Cu group than the −Cu group. At 34 d of lactation, one pathogen-free quarter per animal was infused with 22 cfu of Escherichia coli strain 727. Plasma Cu was greater at −24, 0, 18, 24, 36, 96, 192, and 240h relative to infusion for +Cu animals. Plasma Zn concentration was higher at 24h for the +Cu group. Milk bacterial count (log10 cfu/ml) was lower at 12, 18, and 48h for the +Cu group. Somatic cell count (log10/ml) was lower at 18h in +Cu animals. Clinical score at 24h was lower for +Cu cows, while at 144h, clinical score was lower for −Cu cows. Rectal temperature was lower at 18h for the +Cu group. Plasma ceruloplasmin and Fe, dry matter intake and milk production did not differ. Copper supplementation reduced the clinical response during experimental E. coli mastitis, but duration was unchanged.

Zinc treatment prevents lipopolysaccharide‐induced teratogenicity in mice

During pregnancy, exposure to lipopolysaccharide (LPS) can lead to abortion, preterm delivery, and teratogenicity. The mechanisms underlying these effects are unclear. Both LPS and ethanol are potent inducers of liver metallothionein (MT), a key Zn binding protein. The teratogenic effects of ethanol have been linked to MT-induced changes in maternal-fetal Zn homeostasis, leading tofetal deficiency. This study was designed to assess whether the teratogenic effects of LPS are also related to MT induction and changes in Zn homeostasis. Non-pregnant normal (MT +/+) and MT-null (MT -/-) mice were injected subcutaneously with 0.5 microg/gm LPS and killed over 48 hr. In MT +/+ mice, liver MT concentrations were elevated from 6 hr, and were maximal at 24 hr (30-fold basal), whereas liver Zn levels were also increased from 6 hr. Plasma Zn concentrations decreased by 80% at 6 hr, and were below normal between 6 and 24 hr. In MT -/- mice, plasma Zn levels were increased from basal between 6 and 16 hr. Dams were injected with LPS, saline, or LPS and ZnSO4 (2 microg/gm, MT +/+ only) on Day 8 of gestation (GDS), killed on GD18, and the fetuses examined for malformations. External abnormalities were most prevalent in fetuses from MT +/+ dams exposed to LPS, where 34% of fetuses in each litterwere affected. MT +/+ dams treated with LPS and ZnSO4, and MT -/- dams treated with LPS had litters in which 5.4 and 4.8% of fetuses were abnormal respectively. The findings of this study strongly support the hypothesis that LPS teratogenicity is mediated at least in part by MT-induced changes in maternal Zn homeostasis,which compromises fetal Zn supply.

Zinc Supplementation at the Time of Ethanol Exposure Ameliorates Teratogenicity in Mice

Background: We have previously demonstrated that ethanol teratogenicity in mice is related to the maternal expression of metallothionein (MT), a zinc (Zn)-binding protein. Ethanol induces maternal liver MT, which causes plasma Zn concentrations to decrease as Zn moves into the liver. During pregnancy it is suggested that this change decreases fetal Zn supply and contributes to abnormal development. Here we investigated whether maternal Zn supplementation at the time of ethanol exposure reduces teratogenicity. Methods: Mice were injected with 25% ethanol (0.015 ml/g intraperitoneally at 0 and 4 hr) and ZnSO4 (2.5 μgZn/g subcutaneously at 0 hr) and were killed over 16 hr to ascertain changes in plasma Zn. Plasma Zn concentrations peaked at 2 hr, where levels were 5-fold normal and then returned toward normal over 14 hr. Pregnant mice were treated in a similar manner on gestation day 8 with saline, saline + Zn, ethanol + Zn, or ethanol alone, and fetal abnormalities were assessed on gestation day 18. Results: External abnormalities were most prevalent in offspring from dams treated with ethanol. Zn treatment at the time of ethanol exposure reduced the incidence of fetal abnormalities to basal levels. Litters from dams treated with ethanol + Zn contained more fetuses and fewer fetal resorption sites compared with those from ethanol-treated dams. Conclusions: These findings demonstrate that Zn supplementation at the time of ethanol exposure significantly negates the deleterious effects of ethanol on the fetus.

Zinc Supplementation at the Time of Ethanol Exposure Ameliorates Teratogenicity in Mice

Background: We have previously demonstrated that ethanol teratogenicity in mice is related to the maternal expression of metallothionein (MT), a zinc (Zn)‐binding protein. Ethanol induces maternal liver MT, which causes plasma Zn concentrations to decrease as Zn moves into the liver. During pregnancy it is suggested that this change decreases fetal Zn supply and contributes to abnormal development. Here we investigated whether maternal Zn supplementation at the time of ethanol exposure reduces teratogenicity.Methods: Mice were injected with 25% ethanol (0.015 ml/g intraperitoneally at 0 and 4 hr) and ZnSO4 (2.5 μgZn/g subcutaneously at 0 hr) and were killed over 16 hr to ascertain changes in plasma Zn. Plasma Zn concentrations peaked at 2 hr, where levels were 5‐fold normal and then returned toward normal over 14 hr. Pregnant mice were treated in a similar manner on gestation day 8 with saline, saline + Zn, ethanol + Zn, or ethanol alone, and fetal abnormalities were assessed on gestation day 18.Results: External abnormalities were most prevalent in offspring from dams treated with ethanol. Zn treatment at the time of ethanol exposure reduced the incidence of fetal abnormalities to basal levels. Litters from dams treated with ethanol + Zn contained more fetuses and fewer fetal resorption sites compared with those from ethanol‐treated dams.Conclusions: These findings demonstrate that Zn supplementation at the time of ethanol exposure significantly negates the deleterious effects of ethanol on the fetus.

Angiotensin-converting enzyme and metals in untreated essential hypertension.

Hypertension is an important health problem throughout the world and a risk factor for many diseases. Angiotensin-converting enzyme (ACE), a component of the renin-angiotensin system, has an important role in the regulation of blood pressure. Zinc (Zn), a trace element with important biological functions, is located in the catalytic site of ACE. Calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K) also appear to be involved in hypertension pathogenesis. In this study, plasma ACE activities and Cat, Cai, Mg, Na, K, and plasma/erythrocyte Zn levels of 20 untreated patients with essential hypertension and 28 healthy individuals were evaluated. Plasma ACE activities (p<0.05) and erythrocyte Zn concentrations (p<0.001) were significantly higher in patients with essential hypertension than values of the control group. No significant difference was found between plasma Zn concentrations of the groups (p>0.05). Plasma Cat (p<0.001) and Mg levels (p<0.05) in essential hypertension were significantly lower than those of controls. Plasma Na, K, and Cai levels remained normal in essential hypertension. There are complex associations between metals and arterial pressure. Ca and Mg deficiencies seem to be associated with increased prevalence of hypertension. Increases in erythrocyte Zn may have a future potential use for diagnosis of hypertension.

Efficacy of supplementation of a phytase-producing bacterial culture on the performance and nutrient use of broiler chickens fed corn-soybean meal diets

We evaluated the efficacy of supplementation of active Mitsuokella jalaludinii culture (AMJC) on the growth performance, nutrient use, and mineral concentrations in tibia bone and plasma of broiler chickens fed corn-soybean meal diets. Dietary treatments included low-nonphytate P (NPP) feed (containing 0.24% and 0.232% NPP for chicks from 1 to 21 and 22 to 42 d of age, respectively), low-NPP feed added with different levels of AMJC (equivalent to 250, 500, 750, and 1,000 U phytase/kg of feed), and normal-NPP feed (containing 0.46 and 0.354% NPP for chicks from 1 to 21 and 22 to 42 d of age, respectively). Supplementation of AMJC to low-NPP feed increased (P < 0.05) weight gain and feed intake and decreased (P < 0.05) feed:gain ratio of chickens during the whole experiment (Days 1 to 42). Supplementation of AMJC increased (P < 0.05) the AME value, digestibility of DM and CP, and retention of P, Ca, and Cu. Mn retention in broilers was only increased (P < 0.05) by AMJC supplementation from 18 to 20 d of age, and Zn retention was improved (P < 0.05) only at a high level of AMJC (equivalent to 1,000 U phytase/kg of feed) supplementation. Chicks fed low-NPP feed added with AMJC had similar tibia ash percentages as those fed the normal-NPP diet. Generally, supplementing AMJC to low-NPP feed increased (P < 0.05) Ca, decreased significantly (P < 0.05) Mn and Cu, but did not affect Zn and P concentrations in tibia ash. Supplementing AMJC also increased (P < 0.05) plasma P but had no effect on plasma Ca or Mn. Plasma Zn concentration was increased only when a high level of AMJC (equivalent to 1,000 U phytase/kg of feed) was used. In conclusion, AMJC supplementation to low-NPP feed improved growth performance; AME value; digestibility of CP and DM; use of Ca, P, and Cu; and bone mineralization.

Effect of feeding organic and inorganic sources of additional zinc on growth performance and zinc balance in nursery pigs.

Three experiments were conducted to evaluate the effect of feeding pharmacological concentrations of zinc (Zn), from organic and inorganic sources, on growth performance, plasma and tissue Zn accumulation, and Zn excretion of nursery pigs. Blood from all pigs was collected for plasma Zn determination on d 14 in Exp. 1, d 7 and 28 in Exp. 2, and d 15 in Exp. 3. In Exp. 1, 2, and 3, 90, 100, and 15 crossbred (GenetiPorc USA, LLC, Morris, MN) pigs were weaned at 24+/-0.5, 18, and 17 d of age (6.45, 5.47, and 5.3 kg avg initial BW), respectively, and allotted to dietary treatment based on initial weight, sex, and litter. A Phase 1 nursery diet was fed as crumbles from d 0 to 14 in Exp. 1, 2, and 3, and a Phase 2 nursery diet was fed as pellets from d 15 to 28 in Exp. 1 and 2. The Phase 1 and Phase 2 basal diets were supplemented with 100 ppm Zn as ZnSO4. Both dietary phases contained the same five dietary treatments: 150 ppm additional Zn as zinc oxide (ZnO), 500 ppm added Zn as ZnO, 500 ppm added Zn as a Zn-amino acid complex (Availa-Zn 100), 500 ppm added Zn as a Zn-polysaccharide complex (SQM-Zn), and 3,000 ppm added Zn as ZnO. Overall in Exp. 1, pigs fed 500 ppm added Zn as SQM-Zn or 3,000 ppm added Zn as ZnO had greater ADG (P < 0.05) than pigs fed 150 ppm, 500 ppm added Zn as ZnO, or 500 ppm added Zn as Availa-Zn 100 (0.44 and 0.46 kg/d vs 0.35, 0.38, and 0.33 kg/d respectively). Overall in Exp. 2, pigs fed 3,000 ppm added Zn as ZnO had greater (P < 0.05) ADG and ADFI than pigs fed any other dietary treatment. On d 14 of Exp. 1 and d 28 of Exp. 2, pigs fed 3,000 ppm added Zn as ZnO had higher (P < 0.05) plasma Zn concentrations than pigs on any other treatment. In Exp. 3, fecal, urinary, and liver Zn concentrations were greatest (P < 0.05) in pigs fed 3,000 ppm added Zn as ZnO. On d 10 to 15 of Exp. 3, pigs fed 3,000 ppm added Zn as ZnO had the most negative Zn balance (P < 0.05) compared with pigs fed the other four dietary Zn treatments. In conclusion, feeding 3,000 ppm added Zn as ZnO improves nursery pig performance; however, under certain nursery conditions the use of 500 ppm added Zn as SQM-Zn may also enhance performance. The major factor affecting nutrient excretion appears to be dietary concentration, independent of source.

Effect of Dexamethasone Stress on Concentrations of Zinc in Blood Plasma and in Sub-Cellular Fractions of Various Tissues of Neonatal Buffalo Calves

Effect of chemical stress of daily administration of glucocorticoid (dexamethasone @0.125 mg./calf/day) injections on plasma zinc levels, Zn status of body tissues and its distribution in sub cellular fractions, was studied in neonatal buffalo calves. Daily i/m injections of dexamethasone, starting at the completion of 1 week of age and continued till 8th week, led to a significant decline in plasma Zn concentration from 3rd week onwards, which then persisted throughout the rest of the experimental period. In control group, liver had the highest concentration of zinc, followed by heart, muscle, spleen, kidney and testis. In all these tissues, cytosolic fractions had the highest (>60%) zinc levels followed by nuclear, mitochondrial and microsomal fractions. In dexamethasone treated calves, there was a significant increase in the Zn uptake by the tissues of liver and muscle. This increase in zinc concentration was observed in all the sub cellular fractions of liver and muscle, however about 80% of this increase was in cytosolic fraction. It was concluded that glucocorticoid-induced stress caused increase in Zn levels of liver/muscles and decrease in blood plasma zinc, thus indicating a redistribution of Zn in body. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 7 : 1022-1025)

Interaction of dietary zinc and growth implants on weight gain, carcass traits and zinc in tissues of growing beef steers and heifers

In two separate studies, 60 beef heifers (379 kg BW) and 60 beef steers (348 kg BW) were randomly assigned to six treatments in 2×3 factorial arrangements. The treatments were with or without Synovex ® implants combined with either a control diet or diets supplemented with 200 ppm Zn from ZnSO 4 or zinc methionine (Zn-Met). Near the mid-point of the feeding periods, cattle were vaccinated with a modified live virus and subsequent titers and concentrations of immunoglobulin G (IgG) were measured. Liver and blood samples were obtained 1 week prior to the start of the experiments and at intervals during the experiments. In experiment 1, average daily gains of beef heifers were ( P<0.05) affected by the interaction of implant and source of dietary Zn. Compared to control and ZnSO 4 treatments, supplementation with Zn-Met increased ( P<0.05) the concentration of Zn in serum. Antibody titers and concentrations of IgG in serum were highest ( P<0.05) in heifers fed ZnSO 4 compared to heifers fed the control or Zn-Met supplemented diets. The Synovex-H ® implant reduced the concentrations of Zn and Cu in liver. In experiment 2, Synovex-S ® implants improved ( P<0.05) weight gains of steers supplemented with 200 ppm dietary Zn from ZnSO 4 compared to non-implanted steers. However, the implant had no effect when Zn-Met was the dietary Zn source. The implant increased ( P<0.05) concentrations of Zn in liver of steers supplemented with 200 ppm dietary Zn and reduced Zn in liver of steers fed the control diet. Implanted steers had higher ( P<0.05) Cu status and IgG concentrations in serum than non-implanted steers. Steers supplemented with either ZnSO 4 or Zn-Met had greater ( P<0.05) concentrations of Zn in liver and plasma than steers fed the control diet. These results indicate both the level and source of Zn supplementation in diets of feedlot cattle affect their response to growth implants.

Free-choice consumption of mineral lick blocks by fattening lambs fed ad libitum alfalfa hay and concentrates with different trace mineral content

The objective of this study was to evaluate the ability of lambs to regulate intake of mineral lick blocks (MLBs) with different trace mineral content when alfalfa hay and concentrates, also with a different trace mineral content, were available to lambs for ad libitum consumption. Twelve 4-month-old purebred Karagouniko lambs were divided into three groups, pen housed individually, and fed unchopped alfalfa hay and concentrates ad libitum. The three concentrates used consisted of a basal concentrate food supplemented (TM+) or not (TM−) with trace elements and a vitamin premix. This basal food of the third group (3TM) was supplemented with a premix in which the trace minerals added were three times the amount of the control group, TM+. The experiment lasted 66 days. The first 31 days were used as an adaptation period, and from the 32nd day two different MLBs were put in each pen. One of the MLBs was white in colour while the other was light pink and had a three-fold greater trace mineral content compared to the white one. Two weeks following the introduction of the MLBs (adaptation period), the behaviour of lambs was video recorded for 48 h per week for 3 weeks. Food and water intake and MLB consumption were recorded regularly and the Cu and Zn concentrations were determined in the blood plasma and the liver of the lambs. The average daily MLB intake, the number of visits to the MLBs, and the time spent by the lambs licking the MLBs were higher for the group TM− and lower for the 3TM group. However, the daily mineral intake from the ingested MLB represented only a very small proportion of the total mineral intake of the animals. The differences among the groups in plasma and liver Cu and Zn concentrations represented the quantities ingested via the diet rather the MLBs. In conclusion, the results of this experiment did not show clearly that the lambs could regulate the intake of MLB because they failed to exhibit a ‘mineral wisdom’ related to their physiological needs and mineral status.