Fecal Zinc Excretion Research Articles

Evaluation of a microencapsulated form of zinc oxide on weanling pig growth performance, fecal zinc excretion, and small intestinal morphology.

A total of 300 pigs (DNA 200 × 400; initially 6.0 ± 0.08kg body weight [BW]) were used in a 42-d study to evaluate a microencapsulated form of zinc oxide. At weaning, pigs were randomly allocated to pens, and pens were randomly assigned to dietary treatments with 5 pigs per pen and 12 pens per treatment. Dietary treatments were 1) negative control (CON; standard nursery diet containing 110ppm Zn in the form of zinc sulfate from trace mineral premix); 2) control diet with 400ppm added Zn from ZnO included in phases 1 and 2 (Low-ZnO); 3) control diet with 3,000ppm added Zn from ZnO included in phase 1 and 2,000ppm added Zn from ZnO included in phase 2 (High-ZnO); 4) control diet with 400ppm added Zn from microencapsulated ZnO included in phases 1 and 2 (Low-MZnO; Vetagro S.p.A., Reggio Emilia, Italy); 5) control diet with 3,000ppm added Zn from microencapsulated ZnO in phase 1 and 2,000ppm added Zn from microencapsulated ZnO in phase 2 (high-MZnO; Vetagro S.p.A., Reggio Emilia, Italy). On days 10 and 28, fecal samples from 2 pigs per pen were collected for fecal Zn concentrations, and on day 28, 30 pigs (n = 6) were euthanized, and small intestinal tissues were collected to evaluate morphology. For the entire treatment period (days 0 to 28) there was no evidence of differences in average daily gain (ADG), average daily feed intake (ADFI), or G:F (P > 0.05). During the common phase 3 (days 28 to 42) pigs fed the negative control, High-MZnO, or Low-MZnO had improved (P < 0.0001) ADG and ADFI compared to pigs fed High- or Low-ZnO. For the entire experiment (days 0 to 42), pigs fed Low-ZnO or High-ZnO had reduced (P < 0.0001) ADG compared to those fed the negative control. A significant treatment × day interaction (P = 0.04) was observed for fecal Zn concentrations, where the level of Zn excreted in the feces was dependent on the sampling day in pigs fed a low level of ZnO or low level of microencapsulated ZnO. There was no evidence (P > 0.05) that small intestinal morphology differed significantly between treatments. In summary, feeding a microencapsulated form of ZnO did not alter piglet growth performance during the treatment period. Pigs fed a low level of ZnO or microencapsulated ZnO had reduced fecal Zn excretion by the end of the feeding period, but no significant impacts were observed on piglet small intestinal morphology.

Effects of a potentiated zinc oxide on growth performance, incidence of diarrhea, mineral excretion, and bone breaking strength of nursery pigs

The objective of the present study was to evaluate the effects of a potentiated (PZnO) and conventional source of zinc oxide (ZnO) on growth performance, bone breaking strength, incidence of diarrhea, and fecal excretion of phosphorus (P), zinc (Zn), and copper (Cu) of nursery pigs. A total of 84 pigs weaned at 21 d of age (6.1 ± 0.9 kg) were allotted based on a completely randomized block design. The nutritional program was divided in four dietary phases with four dietary treatments: [NC negative control: no ZnO and regular P levels (0.440; 0.420; 0.400; 0.380%); PC positive control: inclusion of ZnO (3,000, 3,000, 2,200, 1,000 ppm) and regular P levels (0.440; 0.420; 0.400; 0.380%); ZnO + PZnO: association between ZnO (1,000, 1,000, 500, 0 ppm) and PZnO (500, 500, 500, 500 ppm) and 10% low P levels (0.396; 0.379; 0.360; 0.340%); PZnO: inclusion of the PZnO (500, 500, 250, 250 ppm) and 10% low P levels (0.396; 0.379; 0.360; 0.340%)]. Data were analyzed using the GLM procedure of SAS 9.4. Pigs fed diets supplemented with PZnO increased overall ADFI (P &lt; 0.05) when compared with treatment with ZnO. Pigs fed diets supplemented with PZnO reduced (P &lt; 0.05) Zn excretion when compared to treatment with ZnO. The treatments with PZnO reduced (P &lt; 0.05) P excretion during phase 3 when compared with treatment with ZnO. In conclusion, the use of PZnO supplemented at lower levels than the conventional source of ZnO, can be a potential alternative to reduce the environmental impact of the swine production systems by optimizing the P utilization, reducing Zn excretion, and still maintaining an optimal feed intake.

Toward revising dietary zinc recommendations for children aged 0 to 3 years: a systematic review and meta-analysis of zinc absorption, excretion, and requirements for growth.

The Food and Agriculture Organization of the United Nations and the World Health Organization are updating their dietary zinc recommendations for children aged 0 to 3 years. The aim of this review was to retrieve and synthesize evidence regarding zinc needs for growth as well as zinc losses, absorption, and bioavailability from the diet. MEDLINE, Embase, and Cochrane Library databases were searched electronically from inception to August 2020. Studies assessing the above factors in healthy children aged 0 to 9 years were included, with no limits on study design or language. Ninety-four studies reporting on zinc content in tissue (n = 27); zinc absorption (n = 47); factors affecting zinc bioavailability (n = 30); and endogenous zinc losses via urine, feces, or integument (n = 40) met the inclusion criteria. Four reviewers extracted data and two reviewers checked for accuracy. Studies were synthesized narratively, and meta-analyses of zinc losses and gains as well the subgroups of age, type of feeding, country's income, and molar ratio of phytate to zinc were conducted. Meta-analysis revealed an overall mean (95%CI) urinary and endogenous fecal zinc excretion of 17.48 µg/kg/d (11.80-23.15; I2 = 94%) and 0.07 mg/kg/d (0.06-0.08; I2 = 82%), respectively, with a mean fractional zinc absorption of 26.75% (23.69-29.81; I2 = 99%). Subgrouping by age revealed differences in mean values associated with the transition from milk-based diets to solid food during the first 3 years of life. This review synthesizes data that may be used to formulate zinc requirements in young children. Results should be interpreted with caution because of considerable heterogeneity in the evidence. PROSPERO registration number CRD42020215236.

Effects of Protein-Chelated Zinc Combined with Mannan-Rich Fraction to Replace High-Dose Zinc Oxide on Growth Performance, Nutrient Digestibility, and Intestinal Health in Weaned Piglets.

A total of 168 weaned piglets (average initial body weight of 7.70 ± 0.75 kg) were used in a 4-week feeding trial to investigate the effects of dietary supplementation with protein-chelated zinc (Zn-Pro) alone or combined with a mannan-rich fraction (MRF) to replace high-dose zinc oxide (ZnO) for weaned piglets. The dietary treatments included a basal diet as control (CON), a ZnO diet (basal diet + 1600 mg Zn/kg from ZnO), a Zn-Pro diet (basal diet + 60 mg Zn/kg from Zn-Pro), and a MRF plus Zn-Pro diet (MRP, basal diet + 800 mg/kg MRF + 60 mg Zn/kg from Zn-Pro). The average daily gain of piglets in the MRP group was higher (p ≤ 0.05) than that in CON and Zn-Pro groups during d 15-28 and d 1-28 of experiment. The apparent total tract digestibility of dry matter, organic matter, and crude protein in the MRP group was higher (p ≤ 0.05) than that in the CON group. The serum insulin-like growth factor-1 level in the MRP group was markedly higher (p ≤ 0.05) than that of piglets in the other three treatment groups. Piglets fed the Zn-Pro and ZnO diets had greater (p ≤ 0.05) acetic acid in cecal digesta than those fed the CON diet, while the MRP diet had higher (p ≤ 0.05) cecal propionate concentration than those that were fed the CON diet on d 28 of experiment. Moreover, the villus height of ileum in the MRP group tended to be greater than the CON group (p = 0.09). Compared with the CON and MRP groups, the relative abundance of Lactobacillaceae (p = 0.08) and Lachnospiraceae (p = 0.09) in the Zn-Pro group showed an increasing trend. The relative abundance of Prevotellaceae in the Zn-Pro group was significantly lower (p ≤ 0.05) than that in the MRP group. In conclusion, the combined addition of MRF and Zn-Pro acted as a suitable alternative to ZnO to beneficially support the growth performance and intestinal health of weaned piglets, as well as contribute to a lower diarrhea rate and environmental pollution from fecal zinc excretion.

Growth performance, immune status, gastrointestinal tract ecology, and function in nursery pigs fed enzymatically treated yeast without or with pharmacological levels of zinc.

Growth performance and physiological responses of nursery piglets when fed enzymatically treated yeast (HY40) and pharmacological ZnO alone or in combination were investigated. A total of 144 pigs (21 d old, BW 7.32 ± 0.55 kg) were placed in 36 pens (4 pigs/pen). Pigs were randomly assigned to one of four dietary treatments (n = 9): 1) control corn-wheat-soybean meal diet (control), 2) control + HY40 (HY40), 3) control + (ZnO) and 4) control + HY40 + ZnO (HY40+ZnO). Inclusion of HY40 and ZnO was 0.5% and 3,000 ppm in phase I (days 0 to 14), respectively, and halved in phase II (days 15 to 42). All diets contained 0.2% TiO2 for determination of apparent total tract digestibility (ATTD) of components. Body weight and feed disappearance were recorded weekly. One pig per pen was killed for organ weights, blood, and tissue samples on day 14. Except for phase II, when HY40 + ZnO pigs had greater average daily feed intake (P = 0.004) than all other treatments, there were no (P > 0.05) interactions between HY40 and ZnO on growth performance. Pigs fed HY40 or ZnO containing diets were heavier (P < 0.05) than pigs fed without by the end of the study. On day 14, pigs fed additives exhibited higher (P ≤ 0.009) ATTD of dry matter (DM) and gross energy (GE) than control pigs. On day 28, pigs fed control, HY40, and HY40 + ZnO had greater (P ≤ 0.022) ATTD of DM, crude protein, and GE than piglets fed ZnO only. Pigs fed HY40 + ZnO had lower ileal digesta Escherichia coli concentration (P < 0.05) than HY40 and control pigs. Ileal digesta of pigs fed ZnO diets had higher lactobacillus to E. coli ratio (1.44 vs. 1.20; P = 0.001), exhibited higher concentrations of acetic (P = 0.01) and butyric acid (P = 0.01) but lower lactic (P = 0.02) and total short chain fatty acids (P = 0.033) than pigs fed non-ZnO diets. Greater (P < 0.05) mRNA expression of nutrient transporters, tight junction proteins, and fecal excretion of zinc (Zn) was observed in ZnO pigs relative to non-ZnO pigs. Pigs fed HY40 diets had greater (P = 0.002) villus height to crypt depth ratio (VH:CD) than non-HY40 pigs. The concentration of plasma IgA was higher (P = 0.04) in HY40 + ZnO pigs relative to other pigs, whereas HY40 pigs showed higher (P < 0.001) jejunal IgA than non-HY40 pigs. Although the mode of action of HY40 and ZnO differed, the present study indicated that HY40 improved growth performance and jejunal function and immunity, making HY40 an effective alternative to pharmacological ZnO in nursery pigs feeding programs.

Effect of replacing inorganic trace minerals at lower organic levels on growth performance, blood parameters, antioxidant status, immune indexes, and fecal mineral excretion in weaned piglets.

Organic trace minerals (OTMs) have the potential to replace inorganic trace minerals (ITMs), but the degree to which the dietary levels can be reduced is not well defined. This study aimed to investigate the effect of replacing of ITMs with lower levels of OTMs on growth performance, blood parameters, antioxidant status, and immune indexes in weaned piglets. The experiment was conducted in a subtropical city in Guangdong Province in South China (subtropical climate) from July to September 2018. A total of 600 pigs with an average initial BW of 8.90kg were allotted by gender and weight to 5 treatments with 6 replicate pens per treatment. Experimental treatments: (A) Control group (a basal diet with iron, copper, manganese, and zinc from sulfates and sodium selenite providing commercially utilized levels in China of 150, 25, 40, 150, and 0.5mg/kg, respectively). (B) 1/2 ITM group (inorganic trace minerals providing 1/2 control group levels). (C) 1/2 OTM group (1/2 control group trace mineral levels with manganese, iron, zinc, and selenium from Sel-Plex® and Cu from Bioplex®). (D) 1/3 ITM group (1/3 control group trace mineral levels from inorganic forms). (E) 1/3 OTM group (1/3 control group trace mineral levels from organic forms). The results suggest no significant effects of trace mineral sources or levels, on average daily gain (ADG) and average daily feed intake (ADFI) among different treatments during the entire experiment. The level of zinc in serum was significantly decreased in the 1/3 ITM group. The 1/3 OTM group had a significantly higher (P < 0.05) immunoglobulin G (IgG) level in serum. Fecal mineral excretion decreased significantly (P < 0.05) when decreased dietary levels of trace minerals were included at 1/2 and 1/3 levels regardless of sources. Fecal concentrations of zinc excretion were lower (P < 0.05) with 1/2 OTM supplementation than 1/2 ITMs. The present study shows that replacing high doses of ITMs with low concentrations (1/3) of OTMs does not adversely affect the growth performance of piglets. At low levels, total replacement of ITMs with OTMs improved IgG and reduced fecal excretion of copper, zinc, iron, and manganese, thereby mitigating environmental pollution.

Effect of Supplementation of Nano Zinc Oxide on Nutrient Retention, Organ and Serum Minerals Profile, and Hepatic Metallothionein Gene Expression in Wister Albino Rats

A study was conducted to validate the effects of nano form of zinc (NZn) on nutrient digestibility, zinc retention, organ and serum zinc profile, and hepatic metallothionein gene expression in Wistar albino rats (WAR). Nano zinc (NZn) was synthesized through chemical method, by using 0.45M zinc nitrate [Zn(NO3)2.6H2O] and 0.9M sodium hydroxide (NaOH). The NZn particle in its oxide form was characterized by TEM-EDAX and XRD, and found to be in nano range (below 100 nm. Zinc was supplemented to the Wistar albino rats (WAR) through synthetic semi-purified diet either without Zn, or as inorganic zinc (IZn; 25mg/kg), or as synthesized NZn (25, 12.5, 6.25, 3.125 or 50mg/kg DM) for 60days. The zinc content was observed to be significantly (P < 0.05) higher in liver, bone, kidney, and serum due to NZn supplementation where NZn-50 had highest zinc content and control had the least, without affecting Fe, Mn, and Cu. NZn at 12.5mg/kg group rats were either comparable or better than IZn at 25mg/kg in terms of zinc retention, CP digestibility, zinc level in serum, liver, bone, and kidney suggesting its better bioavailability simultaneously also reduced fecal excretion of zinc to the environment. Metallothionein mRNA expression was upregulated in NZn at 25mg/kg and NZn at 50mg/kg than IZn at 50mg/kg. Thus, in WAR, NZn at half of the ICAR recommendation (25mg/kg DM) is as effective as inorganic zinc at 100% of recommended dose.

Excretion of Zinc and Copper Increases in Men during 3 Weeks of Bed Rest, with or without Artificial Gravity

Background: Zinc and copper have many physiologic functions and little or no functional storage capability, so persistent losses of either element present health concerns, especially during extended-duration space missions.Objectives: We evaluated the effects of short-term bed rest (BR), a spaceflight analog, on copper and zinc metabolism to better understand the role of these nutrients in human adaptation to (simulated) spaceflight. We also investigated the effect of artificial gravity on copper and zinc homeostasis.Methods: Zinc and copper balances were studied in 15 men [mean ± SD age: 29 ± 3 y; body mass index (in kg/m2): 26.4 ± 2.2] before, during, and after 21 d of head-down tilt BR, during which 8 of the participants were subjected to artificial gravity (AG) by centrifugation for 1 h/d. Control subjects were transferred onto the centrifuge but were not exposed to centrifugation. The study was conducted in a metabolic ward; all urine and feces were collected. Data were analyzed by 2-factor repeated-measures ANOVA.Results: Urinary zinc excretion values for control and AG groups were 33% and 14%, respectively, higher during BR than before BR, and fecal zinc excretion values for control and AG groups were 36% and 19%, respectively, higher during BR, resulting in 67% and 82% lower net zinc balances for controls and AG, respectively (both P < 0.01), despite lower nutrient intake during BR. Fecal copper values for control and AG groups were 40% and 33%, respectively, higher during BR than before BR (P < 0.01 for both). Urinary copper did not change during BR, but a 19% increase was observed after BR compared with before BR in the AG group (P < 0.05).Conclusions: The increased fecal excretion of copper and zinc by men during BR suggests that their absorption of these minerals from the diet was reduced, secondary to the release of minerals from bone and muscle. These findings highlight the importance of determining dietary requirements for astronauts on space missions and ensuring provision and intake of all nutrients.

Effects of supplemental palygorskite instead of zinc oxide on growth performance, apparent nutrient digestibility and fecal zinc excretion in weaned piglets

AbstractThe aim of this study was to determine the effects of dietary supplementation of palygorskite instead of zinc oxide (ZnO) on growth performance, apparent nutrient digestibility and zinc contents in serum and feces in weaned piglets. One hundred and sixty‐five piglets (28 days of age, 7.10 ± 0.86 kg) were allotted to five treatments on the basis of weight and sex. Each treatment included three replicates of 11 piglets. The piglets were fed the same basal diet supplemented with 0 mg/kg (control group), 1800 mg/kg, 2400 mg/kg, or 3000 mg/kg palygorskite or 2500 mg/kg ZnO for 28 days. There was no significant difference for incidence of diarrhea among the four treatments during the 0–14‐day feeding period. Compared with the control group, piglets offered diets supplemented with 1800 mg/kg palygorskite had higher (P &lt; 0.05) average daily gain (ADG) and crude protein digestibility. Fecal digestibility of energy in 1800 mg/kg palygorskite and ZnO groups were higher (P &lt; 0.05) than that in the control group. Both the zinc concentrations in serum and fecal zinc excretion in palygorskite groups and control group were all lower (P &lt; 0.05) than that in the ZnO group. In conclusion, dietary supplementation with 1800 mg/kg palygorskite can improve growth performance and nutrient digestibility and can also decrease zinc excretion in feces in weaned piglets.

Dietary phytase increases the true absorption and endogenous fecal excretion of zinc in growing pigs given a corn‐soybean meal based diet

We investigated the effect of dietary phytase on the true absorption and endogenous fecal excretion of zinc (Zn) using (67)Zn in growing pigs given a corn-soybean meal based diet. Ten crossbred barrows were fed the control diet containing 90-mg/kg Zn, 2.3-g/kg phytate-phosphorus and 3.7-g/kg non-phytate-phosphorus or the phytase diet containing similar amounts of Zn and phytate-phosphorus, and 1.4-g/kg non-phytate-phosphorus with 750-PU/kg phytase for 12 h/day. On day 6, the pigs were given 200 g of the corresponding diet labeled by (67)Zn for 2 h. We measured feed intake, fecal Zn concentration and (67)Zn abundance for the determination of apparent absorption, true absorption and endogenous fecal excretion of Zn. Although the apparent absorption of Zn did not significantly differ between the dietary groups, the phytase group had significantly more (P < 0.05) true absorption of Zn than the control group. The endogenous fecal excretion of Zn tended to be more (P = 0.07) in the phytase group than in the control group. These results suggest that dietary phytase improves Zn bioavailability through increasing the true absorption of Zn in growing pigs, which results in stimulating the endogenous fecal excretion of Zn when dietary Zn satisfies its requirement.

Effect of Dietary Phytate on Zinc Homeostasis in Young and Elderly Korean Women

Background: Previous studies suggest that consumption of predominantly plant-based diets with high phytate content contribute to zinc deficiency by inhibiting zinc absorption. Age of the individual may also affect the ability to maintain zinc homeostasis.Objective: This study was designed to determine the effect of dietary phytate on zinc homeostasis and to evaluate the effect of age on the capacity to maintain the zinc homeostasis with changes in dietary phytate in young and elderly Korean women.Design and Methods: Seven healthy young women (22–24 yr) and 10 healthy elderly women (66–75 yr) were studied consecutively for 3 months in 2 metabolic periods (MP) in two different metabolic units. During MP1 the women consumed a high phytate (HP) diet (P:Zn molar ratio = 23) for 9 days. After a 10 d wash-out period at home eating their usual diets, a lower phytate diet (LP) (P:Zn molar ratio = 10) was fed in MP2 for 9 d. Phytase was added to selected foods in the high phytate diet to reduce the phytate content of the meals in the LP period. The zinc content of both diets was about 6.5 mg/d. Stable isotopes of Zn (70Zn) were administered intravenously on d 5 of MP 1 and 2 for measuring endogenous fecal zinc excretion. Plasma samples were also collected on d 5 for measuring plasma zinc concentrations by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). 24 hr urine samples were collected for 5 d and complete fecal samples were collected for 9 d after isotope administration. Fractional zinc absorption (FZA) was calculated from mass balance corrected for endogenous fecal zinc (EFZ) excretion and EFZ was determined by using an isotopic dilution technique. Isotopic ratios for FZA and EFZ were measured by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Statistical analyses were done using ANOVA.Results: Both the young and elderly women were in negative zinc balance during the HP period. This was due to a significant decrease in FZA and total absorbed zinc (TAZ) with a HP diet (43 vs 22% in young women, 34 vs 20% in elderly women, p < 0.001). EFZ excretion did not differ in the young and elderly women during the LP and HP periods. Dietary phytate did not alter plasma zinc concentrations or and urinary zinc excretion in either group.Conclusions: Adjustments in zinc homeostasis with an increase in dietary phytate did not differ between young and elderly women in this study.

EFFECTS OF PRENATAL OR POSTNATAL ETHANOL CONSUMPTION ON ZINC INTESTINAL ABSORPTION AND EXCRETION IN RATS

The effect of ethanol consumption, either during the pregnancy or lactation period, on the altered metabolism of zinc is not well-defined; consequently, this study was performed to analyze the effect of chronic ethanol exposure on milk consumption, serum, milk, duodenal absorption, fecal and urinary excretion of zinc in dams and offspring during either gestation or lactation in the rat. A complementary study was performed regarding pregnancy outcome. We evaluated testosterone values, the offspring born/litter and several indices such as fertility, viable gestations and the survival index. To study the effect of chronic alcoholism during gestation or lactation separately, at birth control newborns were cross-fostered to ethanol dams (ED), and the offspring issued from the ethanol treated mothers were cross-fostered to control dams (CD). Thus, three experimental groups of offspring were formed: (i) control offspring receiving no treatment (CO); (ii) offspring exposed to ethanol only during gestation (GO); and (iii) offspring exposed to ethanol only during lactation (LO). All the results were compared with offspring pair-fed groups (PFO) born of the pair-fed dams (PFD). Duodenal absorption of zinc increased significantly in LO offspring when the substrate concentrations in the perfusion medium were 25, 75, and 150 microM. A higher faecal excretion in GO pups compared with those with LO exposure and control groups (CO and PFO). The urine excretion of zinc was higher for LO offspring with respect to the other three experimental groups (CO, GO, and PFO). Maternal adaptation resulted in zinc retention, adequate to meet the demands of pup's growth in the face of a lower diet intake. The zinc status in pups is regulated by a higher absorption of zinc and intestinal conservation of endogenous fecal zinc after postnatal ethanol consumption. The increase in urinary zinc excretion could be responsible for decreased serum zinc. However, we found an increase in serum zinc probably due to an increase in the zinc absorption values.

Effect of adding macro and micro minerals in pig feces fed diets with different levels of probiotic

This study aimed to verify the effect of diets with different doses (0, 100, 200 and 300 ppm) of probiotic on daily fecal production (DFP) and level of macro and micro minerals in feces of nursing (1st and 2nd initial phases) and growing pigs and during total period. The DFP, as percentage of body weight, was different (P&lt;0.05) among treatments only at 1st initial phase. Fecal levels of macro and micro minerals were similar (P&gt;0.05) among treatments, with exception of calcium and sodium excretion at 1st initial phase and calcium, zinc and nickel during total period. The addition of a poliprobiotic to diets do not affect fecal production of nursing and growing pigs. However, the presence of microorganisms, added (levels of 200 and 300 ppm) in diets for nursing and growing pigs reduced fecal excretion of calcium, zinc and nickel.

Dysprosium as a nonabsorbable fecal marker in studies of zinc homeostasis

Dysprosium is a nonabsorbable rare earth element that has had successful application as a marker for fecal excretion of unabsorbed zinc. Our goals were 1) to evaluate the efficacy of administering dysprosium with all meals over several days as a method of determining the completeness of fecal collections, 2) to determine the similarity of gastrointestinal transit kinetics and excretion patterns of dysprosium and zinc tracer administered simultaneously over several days, and 3) to evaluate alternative methods of using the data for fecal excretion of orally administered zinc tracer and dysprosium to measure the fractional absorption of zinc. 70Zn and dysprosium were administered orally with all meals for 5 consecutive days to 7 healthy, free-living adults consuming a constant diet based on habitual intake. Additional tracers, 67Zn and 68Zn, were administered intravenously. Urine and fecal samples were collected during tracer administration and for 8 d after the last dose. Isotope ratios were measured in urine and feces, and total zinc and dysprosium were measured in fecal samples. The mean recovery of dysprosium was 101.3 +/- 2.4%. The zinc oral tracer and dysprosium had similar fecal excretory patterns; the correlation coefficient for 70Zn and dysprosium in fecal samples exceeded 0.99 (P < 0.0001) for each subject. Fractional zinc absorption measurements using various dysprosium methods correlated well (r > 0.95) with those from the fecal monitoring and dual-isotope-tracer ratio methods. Administration of dysprosium is a useful means of determining the completeness of fecal collections and of measuring zinc absorption.

Growth performance, carcass characteristics, plasma minerals, and fecal mineral excretion in grower-finisher swine fed diets with levels of trace minerals lower than common industry levels

Objectives: To determine the impact of lowering levels of supplemental trace minerals (TM) below those commonly fed to grower-finisher swine on fecal mineral excretion, growth performance, carcass characteristics, and economic return. Methods: Pigs (n = 6024) were randomly distributed into four blocks of two barns per block and allotted within block to diets with either Normal (industry levels) or Reduced TM supplementation. Growth performance was measured for each barn, and individual carcass characteristics were recorded at a commercial packing plant. Fecal samples randomly obtained from at least eight pigs per barn were analyzed for zinc, copper, iron, and manganese. Plasma samples from six pigs per barn were analyzed for zinc, copper, and iron. Results: In pigs fed Reduced TM diets, fecal levels were lower for zinc (P &lt; .05), and tended to be lower for copper, iron, and manganese (P &lt; .10), than in pigs fed Normal TM diets. Carcass weight, carcass weight payment, and total payment were greater for pigs fed Reduced TM diets (P &lt; .05), which may have been partly due to greater weight at placement and uneven gender distribution. Backfat thickness, loin depth, percent lean, and lean premium payment did not differ between treatments (P &gt; .05). Implications: Fecal excretion of zinc was significantly lower, and excretion of copper, iron, and manganese tended to be lower, in grower-finisher pigs fed diets containing trace mineral levels lower than common industry standards. Carcass characteristics were not negatively affected.

Metabolic adaptations to low zinc intakes in premenarcheal girls

Zinc deficiency is increasingly recognized as an important cause of mortality and morbidity. Children in developing countries are at especially high risk because of relatively low zinc intakes and poor bioavailability. We assessed the effect of 2-wk adaptation to low zinc intake (4 mg/d) on fractional zinc absorption, endogenous fecal zinc excretion, and urinary zinc excretion. Sixteen healthy 9-14-y-old girls were studied twice in random order after 2-wk adaptation to diets providing either 12 mg/d (high) or 4 mg/d (low) zinc. Fractional zinc absorption and endogenous fecal zinc excretion were measured with use of established stable isotope techniques. Plasma zinc was not significantly lower during the low dietary intake period (1.06 +/- 0.18 mg/L) than during the high dietary intake period (1.14 +/- 0.23 mg/L, P = 0.30). Endogenous fecal zinc excretion was significantly lower during the low intake period (1.08 +/- 0.62 mg/d) than during the high intake period (1.82 +/- 0.95 mg/d, P < 0.026), but there was no significant change in fractional zinc absorption (30.6% +/- 12.4% compared with 26.6% +/- 9.0%, P = 0.32) or urinary zinc excretion (0.68 +/- 0.35 mg/d compared with 0.59 +/- 0.24 mg/d, P = 0.30). Approximate zinc balance was significantly lower during the low-intake period than during the high-intake period (P = 0.007) and significantly (P < 0.0001) less than zero. Short-term zinc restriction in premenarcheal girls leads to a significant decrease in endogenous fecal zinc excretion, which was inadequate to restore normal zinc balance.

Zinc metabolism in adolescents with Crohn's disease.

Low serum zinc concentrations have been reported in Crohn's disease (CD) and overt zinc deficiency has been described, but little is known about the effect of CD on zinc metabolism in adolescents. The aim of this study was to measure zinc absorption, endogenous fecal zinc excretion, urinary zinc excretion, and zinc balance in children with stable CD and in matched controls. Subjects were 15 children, ages 8-18 y, with stable CD, and 15 healthy matched controls. Subjects were adapted to diets providing 12 mg/d elemental zinc for 2 wk, and then admitted for a 6-d metabolic study. Stable zinc isotopes were given intravenously and orally, and urine and feces collected for 6 d. Fractional zinc absorption, endogenous fecal zinc excretion, and zinc balance were calculated using established stable isotope methods. In subjects with CD, zinc absorption (10.9% +/- 6.1 versus 23.4 +/- 15.8, p = 0.008) and plasma zinc concentration (0.85 mg/dL +/- 0.15 versus 1.25 +/- 0.35, p = 0.004) were significantly reduced, compared with controls. Despite this, there were no significant differences in endogenous fecal zinc excretion (2.0 mg +/- 1.5 versus 1.5 +/- 1.5, p = 0.34) or urinary zinc excretion (0.9 mg +/- 0.7 versus 1.0 +/- 0.7, p = 0.47). Zinc balance was significantly lower in CD (-1.5 mg +/- 1.5) than in controls (+0.6 mg +/- 3.1, p < 0.0001). In conclusion, adolescents with CD have significantly reduced zinc absorption. Despite this, they were unable to reduce endogenous fecal zinc excretion to restore normal zinc balance and had a significantly worse zinc balance and lower plasma zinc concentration than controls.

Exchangeable Zinc Pool Size in Infants Is Related to Key Variables of Zinc Homeostasis

The exchangeable zinc pool (EZP) is the sum of the combined pools that exchange with zinc in the plasma within 48-72 h and is thought to be critical for zinc-dependent biological processes. The size of the EZP in adults has been found to be positively related to dietary zinc intake, daily absorbed zinc and fecal excretion of endogenous zinc. In this study, we examine data on EZP size in relation to variables of zinc homeostasis in normal infants on different feeding regimens. Data from 45 male infants who participated in one of four different studies contribute to the analysis. The feeding regimens include exclusive breastfeeding (n = 9; age, 2-5 mo); breastfeeding plus modest supplementation with cow's milk-based formula (n = 16; age, 3-4 mo); exclusive formula feeding (n = 4; age, 3-4 mo) and exclusive breastfeeding plus complementary foods (n =16; age, 7 mo). Fractional absorption was determined by fecal monitoring after oral administration of zinc-stable isotopes. Urine enrichment 4-8 d posttracer was used to determine endogenous fecal zinc (7-mo-old infants excepted) and EZP size. Univariate correlations and multivariate regression analyses were performed between EZP and age, weight, dietary zinc intake, fractional absorption, total absorbed zinc and endogenous fecal zinc. Results include no significant relationship between EZP size and age, body weight or fractional absorption but a positive relationship with daily absorbed zinc and endogenous fecal zinc excretion. We conclude that the amount of absorbed zinc is not tightly regulated, and that endogenous fecal zinc is dependent on and responsive to the zinc status of the organism.

Effects of Pharmacological Levels of Zinc as Zinc Oxide on Fecal Zinc and Mineral Excretion in Weanling Pigs

Eighteen weanling crossbred barrows (7.3 kg; 22 d of age) were used in a randomized complete block design to evaluate the effect of supplemental Zn from ZnO on fecal excretion of Zn and other minerals. Pigs were blocked by BW and penned (two pigs per crate) in stainless steel metabolism crates. Dietary treatments were 0, 2,000, or 3,000ppm supplemental Zn from ZnO. Growth performance and feed intake were measured weekly for a total of 21 d. Excretion of minerals was measured by total fecal collection with indigo carmine marking the beginning and end of each weekly period. No differences (P > 0.05) occurred in ADG, ADFI, and feed/gain (F/G) among treatments. Increasing dietary Zn increased (linear, P < 0.01) Zn intake, absolute absorption of Zn, and absolute fecal excretion of Zn. Increasing dietary Zn also increased absolute excretion of Fe, Cu, and Mn and decreased apparent absorption of P, Fe, and Cu (linear, P < 0.05) for the entire period. Fecal N increased, and N digestibility decreased, with increasing dietary Zn (linear, P < 0.05). Increasing dietary Zn increased fecal DM (quadratic, P < 0.05) and decreased DM digestibility (quadratic, P < 0.05). Increasing dietary Zn also increased liver Zn (quadratic, P < 0.01) and decreased (linear, P < 0.05) liver Cu and Mn. Overall, pharmacological levels of Zn reduced Zn and other mineral apparent absorption and increased fecal mineral excretion.

Zinc Metabolism in Patients with Exocrine Pancreatic Insufficiency

Objective: Metabolism of zinc was studied by administering radioactive zinc (Zn65), and by performing metabolic balance studies in eight patients with exocrine pancreatic insufficiency and eighteen control subjects.Methods: Retention of radioactive zinc was measured by total body counter, and its urinary and fecal excretion by gamma scintillation counter. Metabolic balance studies were carried out by measuring dietary zinc intake as well as fecal and urinary excretion of zinc by atomic absorption spectrophotometry in this group of patients.Results: These studies revealed a 50% reduction in intestinal absorption of Zn65 in patients with exocrine pancreatic insufficiency as compared to alcoholic and non-alcoholic control subjects. In addition, there was a 2 to 4 fold increase (p<0.05) in urinary excretion of zinc in subjects with pancreatic disease. In pancreatic insufficiency, reduced zinc absorption and increased urinary zinc excretion were balanced by lower (p<0.05) endogenous excretion of zinc as evidenced by reduced excretion of Zn65 in feces during the second 4-day period. The mean biological half-life of Zn65 tended to be lower in patients with pancreatic insufficiency as compared to alcoholic control subjects, however the difference did not reach statistical significance.Conclusion: These observations indicate marked alterations in zinc metabolism in patients with advanced chronic pancreatic disease and provide greater insight into development of zinc deficiency in this group of patients.