Apparent Absorption Of Zn Research Articles

Effect of bis-glycinate bound zinc or zinc sulfate on zinc metabolism in growing lambs.

To assess the efficacy of bis-glycinate bound Zn, 36 crossbred wethers (34 ± 2 kg) were sorted by body weight into three groups and stagger started on a Zn-deficient diet (18 mg Zn/kg dry matter [DM]; 22.5% neutral detergent fiber [NDF]) for 45 d prior to a 15-d metabolism period (10 d adaptation and 5 d collection). On day 46, lambs were randomly assigned to dietary treatments (four lambs treatment−1group−1): no supplemental Zn (CON) or 15 mg supplemental Zn/kg DM (ZINC) as Zn sulfate (ZS) or bis-glycinate (GLY; Plexomin Zn, Phytobiotics). Blood was collected from all lambs on days 1, 44, 56, and 61. Liver, jejunum, and longissimus dorsi samples were collected after euthanasia on day 61. Gene expression was determined via quantitative real-time polymerase chain reaction. Data were analyzed using ProcMixed of SAS (experimental unit = lamb; fixed effects = treatment, group, and breed) and contrast statements assessed the effects of supplemental Zn concentration (ZINC vs. CON) and source (GLY vs. ZS). After 15 d of Zn supplementation, plasma Zn concentrations were greater for ZINC vs. CON and GLY vs. ZS (P ≤ 0.01); tissue Zn concentrations were unaffected (P ≥ 0.27). Liver Cu concentrations were lesser for ZINC vs. CON (P = 0.03). Longissimus dorsi Mn concentrations were greater for ZINC vs. CON (P = 0.05) and tended to be lesser for GLY vs. ZS (P = 0.09). Digestibility of DM, organic matter (OM), and NDF was lesser for ZINC vs. CON (P ≤ 0.05); acid detergent fiber digestibility tended to be greater for GLY vs. ZS (P = 0.06). Nitrogen retention (g/d) tended to be greater for GLY vs. ZS (P = 0.10), and N apparent absorption was lesser for ZINC vs. CON (P = 0.02). Zinc intake, fecal output, retention, and apparent absorption were greater for ZINC vs. CON (P ≤ 0.01). Apparent absorption of Zn was −5.1%, 12.8%, and 15.0% for CON, ZS, and GLY, respectively. Nitrogen and Zn retention and apparent absorption were not correlated for CON (P ≥ 0.14) but were positively correlated for ZINC (retention: P = 0.02, r = 0.52; apparent absorption: P < 0.01, r = 0.73). Intestinal expression of Zn transporter ZIP4 was lesser for ZINC vs. CON (P = 0.02). Liver expression of metallothionein-1 (MT1) tended to be greater for GLY vs. ZS (P = 0.07). Although Zn apparent absorption did not differ between sources (P = 0.71), differences in post-absorptive metabolism may be responsible for greater plasma Zn concentrations and liver MT1 expression for GLY-supplemented lambs, suggesting improved bioavailability of GLY relative to ZS.

161 Effects of Supplemental Zn Source (sulfate or Bis-glycinate) on Metabolism, Apparent Absorption, and Retention of Zn by Lambs

Abstract To assess bioavailability of bis-glycinate Zn (Plexomin Zn, Phytobiotics), 36 crossbred wethers (34 ± 2 kg) were sorted by body weight into three groups and stagger started on a Zn deplete diet (18.6 mg Zn/kg dry matter [DM]; 22.5% neutral detergent fiber) for 45 d prior to a 15-d metabolism period (10 d adaptation, 5 d collection). On d 46, lambs were randomly assigned to dietary Zn treatments (4 lambs/treatment/group): no supplemental Zn (CON) or 15 mg supplemental Zn/kg DM as Zn sulfate (ZS) or bis-glycinate Zn (GLY). Blood was collected from all lambs on d 1, 44, 56, and 61. Liver, small intestine, and muscle samples were collected after euthanasia on d 61. Liver and intestinal gene expression was determined via quantitative real-time polymerase chain reaction. Data were analyzed using ProcMixed of SAS (experimental unit = lamb; fixed effects = treatment, group, and breed). After 15 d of Zn supplementation, plasma Zn concentrations were greatest for GLY versus CON or ZS (P ≤ 0.01), but tissue Zn concentrations were unaffected (P ≥ 0.15). Liver MT1 expression was approximately 2-fold greater for GLY versus CON or ZS (P ≤ 0.07). Intestinal ZIP4 expression tended or was lesser for ZS or GLY versus CON (P ≤ 0.07) and ZNT1 expression tended to be lesser for ZS versus CON (P = 0.07). Zinc intake, fecal output, retention, and apparent absorption were greater for ZS or GLY versus CON (P ≤ 0.01). Apparent absorption of Zn was -5.1, 12.8, and 15.0% for CON, ZS, and GLY, respectively. Although Zn apparent absorption did not differ between supplemental Zn sources (P = 0.71), differences in post-absorptive metabolism may be responsible for the observed increase in circulating Zn concentrations and liver MT1 expression in GLY supplemented lambs, suggesting improved bioavailability of GLY relative to ZS.

Trace mineral metabolism and nutrient digestibility in lambs supplemented with zinc sulfate during an adrenocorticotropic hormone challenge

The objective was to evaluate the effects of Zn supplementation and adrenocorticotropic hormone (ACTH) injections on nutrient digestibility, trace mineral metabolism and status. It was hypothesized that ACTH would decrease nutrient digestibility and Zn retention, but Zn supplementation would improve Zn retention, regardless of ACTH administration. Twenty-two Polypay cross weathers previously enrolled in a trial, consumed a moderately Zn deplete diet (22 mg Zn/kg DM) for 52 d, followed by being housed in metabolism crates for 15 d while receiving one of two diets: CON (Zn deplete diet) or ZINC (CON plus 40 mg Zn/d from ZnSO4). Lambs rested for one day outside of crates then returned to crates for this 5 d study. Lambs continued to receive dietary Zn treatments and were randomly assigned to receive injectable treatments, once daily on d 1–4 at feeding: SALINE (2 mL saline I.M.), STRESS (80 I.U. ACTH I.M.); lamb was experimental unit (n = 5–6/treatment) in a 2 × 2 factorial design. Total fecal and urine collection was conducted on d 3–5, and blood samples were collected on d 0, 1, and 4, 3 h post feeding. Day 4 plasma Zn concentrations, covariate adjusted with d 0 concentrations, displayed a diet × injection tendency (P = 0.06) where ACTH given to ZINC lambs depressed plasma Zn to values similar to CON lambs. Day 1 and 4 cortisol concentrations determined 3 h after injection administration were increased in STRESS vs. SALINE (P < 0.01). Day 4 plasma Cu concentrations, covariate adjusted with d 0 concentrations were lesser in STRESS vs. SALINE (P = 0.04). Day 4 plasma Fe concentrations were unaffected by diet or injection treatment (P ≥ 0.18). Apparent absorption of Zn was increased (P < 0.01) in CON vs. ZINC, but were similar in STRESS vs. SALINE (P = 0.13). Zinc retention, and apparent absorption of Mn and Cu was similar across treatments (P ≥ 0.19). Organic matter (OM) digestibility tended to be decreased in ZINC vs. SALINE (P = 0.07); neutral detergent fiber (NDF) and acid detergent fiber (ADF) digestibility were decreased (P ≤ 0.04) in ZINC vs. SALINE. Injection treatment had no effect on macronutrient digestibility (P ≥ 0.37). The CON lambs were marginally Zn deficient based on plasma Zn concentrations and rate of apparent absorption, while fiber digestion was impaired by Zn supplementation. Plasma cortisol concentrations indicate lambs receiving ACTH experienced physiological stress, however this had limited effects on macro or micronutrient metabolism.

The influence of supplemental zinc and dietary fiber concentration on mineral retention of beef steers.

The objective was to determine if zinc (Zn) retention improved with supplemental Zn above recommended concentrations with increasing dietary fiber concentration. Angus steers (n = 32; 309 ± 4.2 kg body weight [BW]) with GeneMax gain scores of 3, 4, or 5 were utilized in a 2 × 2 factorial arrangement (8 steers per treatment). Steers were stagger started (four blocks of eight steers) and stratified by BW within growing diets to one of two Zn strategies (ZNTRT), no supplemental Zn (analyzed 36 mg Zn/kg dry matter [DM]; CON) or supranutritional Zn (CON + 60 mg Zn/kg DM as ZnSO4 + 60 mg Zn/kg DM as Zn–amino acid complex; SUPZN). Dietary fiber strategies (FIBER) were formulated to target two fiber supplementation rates representing high fiber (HF; ~35% neutral detergent fiber [NDF]) or low fiber (LF; ~25% NDF). Within block, steers received HF for 60 d; then pens were randomly assigned to LF or HF for finishing. Steers fed LF were transitioned for 15 d; on day 75, steers were moved to metabolism crates and adapted for 10 d, followed by 5 d of total fecal and urine collection. Retention of Zn, Mn, Fe, Cu, and N were calculated. The model for analysis of metabolism data included the fixed effects of ZNTRT, FIBER, block, and the interaction of ZNTRT × FIBER, with the three-way interaction of ZNTRT × FIBER × block as random. Steer was the experimental unit (n = 8 per treatment combination). Zinc did not affect initial 60-d performance (P ≥ 0.62). DM and organic matter digestibility were lesser (P = 0.02) and N digestibility tended to be lesser (P = 0.07) in CON vs. SUPZN. Intake and digestibility of NDF and acid detergent fiber were greater (P ≤ 0.01) in HF vs. LF. Digestibility and retention of N as a percentage of intake were greater (P ≤ 0.04) whereas N retention as grams per day tended to be greater in HF vs. LF (P = 0.06). Apparent absorption of Zn tended to be greater (P = 0.06) in CON vs. SUPZN. A ZNTRT × FIBER effect was identified for Zn retention (milligrams per day; P = 0.01) where within SUPZN Zn retention was greater in HF vs. LF (P < 0.01). Apparent absorption and retention of Zn were greater (% of intake; P ≤ 0.02) in HF vs. LF. Apparent absorption of Cu, Fe, and Mn was unaffected by ZNTRT or FIBER (P ≥ 0.24). Increasing dietary Zn increased Zn retained regardless of changes in coefficient of absorption. In addition, dietary fiber content may impact trace mineral and N metabolism by steers, potentially due to increased release of these nutrients from feed as fiber digestibility increases. It appears dietary Zn concentrations and diet composition influence trace mineral absorption in beef steers.

Effect of source of trace minerals in either forage- or by-product–based diets fed to dairy cows: 2. Apparent absorption and retention of minerals

Eighteen multiparous cows were used in a split-plot replicated Latin square with two 28-d periods to evaluate the effects of source of supplemental Cu, Zn, and Mn (sulfates or hydroxy) on apparent absorption of minerals when fed in either a forage- or by-product-based diet. The by-product diets were formulated to have greater concentrations of NDF and lesser concentrations of starch, and specific ingredients were chosen because they were good sources of soluble fiber and β-glucans, which bind trace minerals in nonruminants. We hypothesized that hydroxy trace minerals would interact less with digesta and have greater apparent absorption compared with sulfate minerals, and the difference in apparent absorption would be greater for the by-product diet compared with the forage-based diet. During the 56-d experiment, cows remained on the same fiber treatment but source of supplemental trace mineral was different for each 28-d period; thus, all cows were exposed to both mineral treatments. During each period cows were fed no supplemental Cu, Zn, or Mn for 16 d, followed by 12 d of feeding supplemental minerals from either sulfate or hydroxy sources. Supplemental minerals for each of the mineral sources fed provided approximately 10, 35, and 32 mg/kg of supplemental Cu, Zn, and Mn, respectively, for both fiber treatments. Total Cu, Zn, and Mn dietary concentrations, respectively, were approximately 19, 65, and 70 mg/kg for the forage diets and 21, 85, and 79 for the by-product diets. Treatment had no effect on dry matter intake (24.2 kg/d) or milk production (34.9 kg/d). Cows consuming the by-product diets had greater Zn (1,863 vs. 1,453 mg/d) and Mn (1,790 vs. 1,588 mg/d) intake compared with cows fed forage diets, but apparent Zn absorption was similar between treatments. Manganese apparent absorption was greater for the by-product diets compared with the forage diets (16 vs. 11%). A fiber by mineral interaction was observed for Cu apparent absorption, as cows fed hydroxy minerals with forage diets had greater apparent absorption compared with cows fed sulfate minerals; however, the opposite was observed with the by-product diets. Source of supplemental trace minerals and type of fiber in diets affected availability of Cu and Mn and should be considered in ration formulation.

No indications that zinc and protein source affect Zn bioavailability in sows during late gestation fed adequate dietary Zn concentrations

Previous in vitro research has shown the possibility of spontaneous chelation of Zn in the presence of easily digestible protein sources. The objective of this study was to investigate the possible interaction between zinc (Zn) source and protein source on the in vivo Zn bioavailability in sows during late gestation that were fed adequate dietary Zn concentrations. Fifty-six sows were randomly allocated to one of four dietary treatment groups during a 20-day experimental period: (1) organic Zn+soybean meal, (2) inorganic Zn+soybean meal, (3) organic Zn+hydrolysed feather meal, and (4) inorganic Zn+hydrolysed feather meal. Zinc was provided at adequate dietary Zn concentrations, in which organic Zn was added as a Zn amino acid complex and inorganic Zn as ZnO. Blood samples were collected at the start (day 1) and at the end (day 20A) of the experimental period before feeding and 3h after feeding (day 20B) to determine plasma Zn and serum metallothionein (MT) concentration. Faecal samples were collected rectally, alternately in the morning (day 15, 17, and 19) and afternoon (day 16, 18, and 20) directly after feeding to calculate apparent nutrient digestibility and apparent Zn absorption. Neither Zn nor protein source affected Zn status (plasma Zn: P=0.288 and P=0.237, respectively, Serum MT: P=0.161 and P=0.193, respectively) or apparent Zn absorption (P=0.360 and P=0.527, respectively). Hydrolysed feather meal showed lower crude protein, crude fat, and crude ash digestibility compared to soybean meal (P<0.001). Faecal Zn concentration was not affected by Zn source (P=0.442). This study did not confirm the earlier observed in vitro effect of protein source on Zn bioavailability and shows that, at adequate levels commonly used in practice, the choice of Zn or protein source does not influence Zn status.

Mutation in porcine Zip4-like zinc transporter is associated with pancreatic zinc concentration and apparent zinc absorption

The aim of the present study was to analyse the sequence variability of the porcine Zip4-like Zn transporter gene and the association of identified sequence variants with average daily gain, apparent Zn absorption, plasma Zn concentration and Zn concentration in the liver and pancreas. For the purpose of the study, two different sample sets were used. Set one, which was used for sequencing and association analysis, included mRNA from intestinal tissue from thirty-five piglets of a feeding trial. Sample set two consisted of forty-six samples of genomic DNA from sperm or tissue of wild boars and several pig breeds and was used to genotype animals of different breeds. The sequence analysis of porcine Zip4-like complementary DNA in sample set one revealed the presence of seven nucleotide substitutions. Of these, six were synonymous, whereas a substitution of A with C in exon IX (XM_001925360 c.1430A>C) causes an amino acid exchange from glutamic acid to alanine (p.Glu477Ala). The association analysis revealed no influence of the six synonymous substitutions on Zn values, but the non-synonymous nucleotide exchange significantly increased Zn concentration in the pancreas and apparent Zn absorption of the piglets in week 2 of the feeding trial. The parentage of the piglets and the genotyping results in sample set two suggest a breed-specific presence of the A allele in Piétrain for this amino acid substitution. These results indicate that genotype influences the Zn absorption abilities of individual animals, which should be taken into consideration in animal breeding as well as for the selection of experimental animals.

Apparent zinc absorption and zinc status of weanling rats fed moderately zinc‐deficient diets enriched with beef tallow or sunflower oil

The aim of the study was to compare apparent Zn absorption and Zn status of weanling rats fed diets that differed in Zn level, fat level and fat source. Semi-synthetic diets, which were about isoenergetic and contained 3% soyabean oil, were supplemented with 7 or 100 mg Zn/kg to create a mild Zn deficiency (LZ) or a high Zn supply (HZ) and with 0 (LF), 22% beef tallow (BT) or 22% sunflower oil (SF) according to a 2 × 3 factorial design of treatments. They were fed ad libitum to 6 × 8 rats for 28 days. Energy intake and growth rates were comparable among the HZ groups. Weight gains in the LZ-LF, LZ-BT and LZ-SF groups averaged 5.54, 4.95 and 4.15 g/day, and apparent Zn absorption averaged 79.4, 60.3 and 48.0 μg Zn/day, respectively, whereas faecal Zn excretion was comparable among these groups. Apparent Zn absorption, and plasma and femur Zn concentrations were lower in the high-fat groups than in the LF group, possibly due to the high cellulose content of the BT and SF diets. Plasma Zn concentrations were higher in the animals fed the BT-based than in the SF-based diets, whereas femur and soft tissue Zn concentrations were comparable among these groups. The differences between the LZ-BT and LZ-SF groups in growth rate, Zn absorption rate and Zn status were confirmed in a second experiment. The results indicate that moderately Zn-deficient diets enriched with SF in relation to BT affect Zn metabolism of weanling rats by a yet unknown mechanism.

Determination of true absorption and fecal endogenous loss of zinc in goats

We determined the true absorption and endogenous fecal loss of zinc (Zn) in goats using its stable isotope. Three goats were fed with the diet containing 50 mg/kg Zn twice a day for 17 days. In the morning of day 11, the goats were given a meal labeled by (67) Zn as the tracer with dysprosium as the unabsorbed marker. Then the goats were given unlabeled diet as the rest of the morning feed. We measured dietary and fecal Zn concentration, (67) Zn abundance and dysprosium concentration in feces. The excretion pattern of the tracer Zn into feces differed from that of dysprosium. Therefore, we directly calculated the true absorption of Zn from Zn concentration and (67) Zn abundance in fecal samples collected after the labeled diet was given. The apparent absorption of Zn was -0.009 ± 0.016 mg/kg bodyweight (fractional absorption, -1.07 ± 1.85%). The true absorption of Zn was 0.162 ± 0.018 mg/kg bodyweight (fractional absorption, 18.25 ± 2.01%). The endogenous fecal loss of Zn was 0.172 ± 0.004 mg/kg bodyweight and the intestinal secretion of Zn was 0.210 ± 0.009 mg/kg bodyweight. The present experiment indicates that stable isotopic Zn is a powerful tool for examining Zn metabolism in ruminants.

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.

Interactions of Dietary Microbial Phytase, Citric Acid and Crude Protein Level on Mineral Utilization by Rohu, Labeo rohita (Hamilton), Juveniles

Abstract A 2 × 2 × 2 factorial experiment was designed to study the effect of microbial phytase (MP), citric acid (CA), and crude protein (CP) and their interactions on mineral utilization by rohu, Labeo rohita, juveniles. Two basal diets containing 25% (subnormal) or 35% (normal) CP were supplemented with MP (units, U/kg) and CA (%) at 0, 0; 500, 0; 0, 3; and 500, 3, respectively and fed to 125 juveniles (average initial weight: 13.16 g/fish). MP did not affect fecal ash content but CA (3%) addition activated MP. Apparent absorption of Zn, its content in whole body and plasma, was significantly (P &lt; 0.05) higher in CA‐ and MP‐fed groups. Interaction between CA and MP was found for increased absorption of Na, P, K, Mn, Mg, Fe, and N, their concentrations in whole body and plasma. Cu and Ca absorption, and their concentration in body and plasma were increased as a result of addition of CA, MP, or their interaction. Thus, bioavailability of major minerals was highest in groups fed diets containing 500‐U MP and 3% CA. This improvement was more prominent in subnormal CP diet. Growth performance was also highest in this group. Thus, CA and MP at 25% CP diet had synergistic effect on mineral bioavailability in L. rohita.

Development of iron deficiency decreases zinc requirement of rats.

Effects of the development of Fe deficiency on changes in Fe and Zn metabolism and its possible interactions with dietary Zn were determined. Adequate (25 microg/g) and marginally deficient (5 microg/g) Zn diets containing a sufficient (40 microg/g) dietary Fe levels were fed for 2 wk. Thereafter, both dietary Zn groups were fed an Fe-deficient (2.2 microg/g) diet for 4 wk. It was found that the effects of an Fe-deficient diet began to occur 7 and 14 d after feeding the Fe-deficient diet. At this time, tissue Fe concentrations were depleted and rats were unable to maintain hemoglobin levels. The Fe-deficient diet also induced an immediate fall in plasma Fe concentration, transferrin saturation, and apparent Fe absorption, while the concentrations of liver cytochrome c increased as Fe deficiency developed. Decreases in liver and spleen Fe levels, as well as the activities of blood and bone marrow aminolevulinic acid dehydratase (ALA-D, EC 4.2.1.24) were observed 3, 7, and 14 d after feeding the Fe-deficient diet, and thereafter they were increased. On the other hand, the activity of plasma alkaline phosphatase (ALK-P, EC 3.1.3.1) decreased continuously as Fe deficiency progressed. With severe development of Fe deficiency, rats fed the Zn-adequate diet had increased levels of Zn concentration in the plasma, liver, spleen, kidney, and femur, whereas apparent Zn absorption was decreased. The decrease in apparent Zn absorption and the increase in tissue Zn concentration of rats might be related to the lowered Zn requirement, which is associated with the depressed Zn metabolism caused by feeding Fe-deficient diets.

Consumption of silk protein, sericin elevates intestinal absorption of zinc, iron, magnesium and calcium in rats

Rats were examined for the effect of consumption of silk protein, sericin on the intestinal absorption of Zn, Fe, Mg and Ca. Male Wistar rats were fed on the diet containing either 23% egg albumin or 20% egg albumin plus 3% sericin for 12 d. Consumption of sericin elevated the apparent absorption of Zn, Fe, Mg and Ca (41%, 41%, 21% and 17%, respectively), but did not affect serum concentrations of these elements. Urinary excretion of the elements was unaffected by dietary sericin. The results suggest that consumption of sericin enhances bioavailability of Zn, Fe, Mg and Ca in rats.

Wholewheat flour ensures higher mineral absorption and bioavailability than white wheat flour in rats

Consumption of unrefined whole flour is thought to affect mineral bioavailability because it contains high levels of fibre and phytic acid. The present experiment was designed to study the absorption of minerals from diets based on wholewheat flour and white wheat flour in rats. Two groups of male Wistar rats were fed on the diets for 3 weeks and absorption and tissue retention of minerals were studied. The rats fed on the wholewheat flour diet had significantly greater food intake, weight gain, faecal excretion and intestinal fermentation than those fed on the white flour diet. Mineral intakes, except for Ca, were significantly greater in rats fed on the wholewheat flour diet (4-fold for Mg, 2-fold for Fe and Zn). A significant rise in the apparent absorption of Fe (%) and a significant decrease in the apparent absorption of Zn (%) were observed. The amounts of minerals absorbed (mg/d) were significantly enhanced (excepted for Ca) with the wholewheat flour diet. Moreover, plasma and tibia levels of Mg and plasma, liver and tibia levels of Fe were significantly increased in rats fed on the wholewheat flour diet compared with those fed on the white flour diet. In conclusion, wholewheat flour, rich in phytic acid and minerals, did not have a negative effect on mineral absorption, but rather improved the bioavailability of some minerals. Human studies are needed to confirm these rat results before extrapolation to human nutrition.

Cadmium accumulation, zinc status, and mineral bioavailability of growing rats fed diets high in zinc with increasing amounts of phytic acid.

Five groups of individually housed albino rats (n = 7, initial average weight = 48 g) were fed diets based on egg albumen and cornstarch (basal diet 8.2 g Ca, 6.0 g P, 0.7 g Mg, 225 mg Zn, 150 mg Fe, 60 mg Mn, 8 mg Cu, and 5 mg Cd) over a 4-wk period. Group I (control) was fed the basal diet free of phytic acid (PA). In groups II, III, IV, and V, cornstarch was replaced by 3.5, 7.0, 10.5, and 14.0 g sodium phytate/kg diet, respectively. Daily gain, feed efficiency, Zn status (Zn in plasma, femur, testes, liver and kidneys, activity of the plasma alkaline phosphatase) and apparent absorption of Zn, Fe, Cu, and Mn remained unchanged by the different dietary treatments. PA decreased apparent Mg absorption significantly and apparent absorption of Ca in tendency. Increasing the amount of phytate caused a corresponding enhancement of amount of the digestible P. Cd accumulation in the liver was not significantly altered, and kidney Cd accumulation slightly increased owing to PA. In conclusion, it was shown that under conditions of high dietary Zn, PA had only little effect on the carryover of Cd in growing rats.

Zinc and calcium apparent absorption from an infant cereal: a stable isotope study in healthy infants.

Fractional apparent absorption of Zn and Ca from a wheat-milk-based infant cereal was studied in six healthy infants (18-30 weeks old). Mineral absorption was measured by a stable-isotope technique based on faecal excretion of the isotopes. Each test meal (40 g cereal) was extrinsically labelled with 70Zn and 42Ca before intake. All faecal material passed during the 21 d following intake of the labelled test meal was collected on trace-element-free nappies. Individual stool samples were analysed for their content of 70Zn and 42Ca by thermal ionization mass spectrometry. Apparent absorption was calculated as intake minus total faecal excretion of the isotopes over 68-92 h after administration. The fractional apparent absorption values for Zn and Ca were 33.9 (SD 16.4) % (range 19.2-63.9%) and 53.5 (SD 12.6) % (range 36.7-71.7%) respectively. Re-excretion of absorbed 70Zn (> 68-92 h to 21 d after intake of the labelled meal) was 0.44 (SD 0.38) % of administered dose while only one infant re-excreted detectable amounts of 42Ca (1.74% of administered dose). The analysis of individual stool samples confirmed that 72 h is a sufficient time period for complete collections of non-absorbed isotopes in faecal material from infants during the weaning period and that re-excretion of initially absorbed 70Zn and 42Ca (> 68-92 h to 21 d after intake of the labelled meal) is negligible.

Zinc and calcium apparent absorption from an infant cereal: a stable isotope study in healthy infants

AbstractFractional apparent absorption of Zn and Ca from a wheat-milk-based infant cereal was studied in six healthy infants (18-30 weeks old). Mineral absorption was measured by a stable-isotope technique based on faecal excretion of the isotopes. Each test meal (40 g cereal) was extrinsically labelled with 70Zn and 42Ca before intake. All faecal material passed during the 21 d following intake of the labelled test meal was collected on trace-element-free nappies. Individual stool samples were analysed for their content of ‘OZn and 42Ca by thermal ionization mass spectrometry. Apparent absorption was calculated as intake minus total faecal excretion of the isotopes over 68-92 h after administration. The fractional apparent absorption values for Zn and Ca were 33.9 (SD 164) % (range 19.2-639 %) and 53.5 (SD 12.6) %) (range 36.7-71.7 %) respectively. Re-excretion of absorbed 70Zn (&gt; 68-92 h to 21 d after intake of the labelled meal) was 044 (SD 038) %] of administered dose while only one infant re-excreted detectable amounts of 42Ca (1.74%) of administered dose). The analysis of individual stool samples confirmed that 72 h is a sufficient time period for complete collections of non-absorbed isotopes in faecal material from infants during the weaning period and that re-excretion of initially absorbed 70Zn and 42Ca (&gt; 68-92 h to 21 d after intake of the labelled meal) is negligible.

Apparent absorption of Ca, P and Zn, and true absorption of 65Zn in rats fed diets containing lupin ( Lupinus angustifolius) seed meal or its fractions

The effects of lupin ( Lupinus angustifolius, cultivar ‘Unicrop’) seed meal or some of its fractions on the apparent and true absorption of minerals were studied in three experiments. Groups of four growing rats were pair-fed for 10 days (Experiments 1 and 2) or for 14 days (Experiment 3) on diets which contained the same amounts of energy and protein, and supplemented with amino acids and minerals to target requirements. In Experiment 1, the apparent absorption of Ca, P and Zn was compared in animals fed a control (lactalbumin-based, LA) and a lupin meal (LM) diet. In addition, three lupin fractions were tested, two protein fractions (aqueous dialysed, soluble (ADS); aqueous dialysed, insoluble (ADI) and a residue (LR) containing most of the material from the meal insoluble in water and phosphate-buffered saline (PBS). In Experiment 2, the true absorption of 65Zn was determined in three groups of rats given the following diets: LA (control), LM (lupin meal diet) and LR (diet containing the insoluble material). The inclusion of lupin protein fractions (ADS and ADI) in the diet had no significant effect on the apparent absorption of Ca, P or Zn. The apparent absorption of Ca was not affected by the inclusion in the diet of either lupin seed meal or its fractions but the apparent absorption of P was significantly lower in rats fed whole lupin meal diets (50.8%) than in those given the control diet (63.7%). The apparent absorption of Zn was also significantly lower in rats fed diets containing lupin meal (5.9%) or the insoluble residue (6.5%) compared with that of control animals (26.8%). The true absorption of 65Zn was decreased in animals fed on diets containing lupin meal (22.2%) or insoluble lupin residue (30.9%) in comparison with that of controls (41.9%). Growth was significantly retarded in rats given a lupin based diet with limited Zn supply (12 mg Zn kg −1) compared with those given a lupin diet containing 40 mg Zn kg −1 (Experiment 3). The results suggest that insoluble non-starch polysaccharides and phytate are mainly responsible for the lower availability of Zn in rats fed diets containing lupin meal as the only source of protein. Furthermore, growth can be compromised in animals fed on lupin-based diets when the total Zn supply of the diet is limiting.

Assessment of zinc bioavailability: studies in rats on zinc absorption from wheat using radio- and stable isotopes

Absorption from wheat intrinsically and extrinsically labelled with 67Zn and extrinsically labelled with 65Zn was measured from 67Zn faecal excretion and 65Zn whole-body retention in rats. There were significant differences between the extrinsically- and intrinsically-labelled 67Zn (P < 0.001), but not between the extrinsically-labelled 65Zn and intrinsically-labelled 67Zn. The effect of chicken meat on the absorption of Zn from intrinsically-labelled wheat was also studied in the rat. Mean Zn absorption from wheat and chicken meat fed separately was 18.5 and 68.2% respectively, and from a mixture of the two containing the same level of Zn was 50.1%. The apparent absorption of Zn from the composite meal was significantly higher than predicted from the results of the foods on their own (P < 0.001).

Sulfate supplementation of Angora goats: sulfur metabolism and interactions with zinc, copper and molybdenum

Effects of S intake on Zn, Cu, and Mo metabolism in Angora goats were studied. Animals were fed isocaloric and isonitrogenous diets containing 0.16%, 0.23%, 0.29% or 0.34% S of DM. Dietary Zn, Cu and Mo were constant at 29.2, 8.8 and 1.0 ppm, respectively. Supplementation of dietary S level did not affect ( P>0.20) feed intake, fecal DM output, urinary volume, and fecal S output; but increased urinary S output (linear, P<0.0001), sulfate concentration in feces (linear, P<0.0001; quadratic, P<0.05), and apparent absorption and net retention of S (linear, PP<0.001). Metabolic fecal S, endogenous urinary S, and biological values of supplemented S were 0.55 g/d (32.2 mg/BW kg 0.75), 0.48 g/d (27.8 mg/BW kg 0.75) and 62.7%, respectively. Serum Cu and Zn concentrations were not affected by added S, although concentrations were lower ( P<0.05) at 2 and 4 h than at 0 and 6 h postprandial. Concentration of protein S in the rumen, apparent absorption of Zn (quadratic, P<0.05), and Zn retention (quadratic, P<0.05) increased with S intake. Urinary Zn excretion increased ( P<0.05) when diets containing higher amounts of S were fed. Presumably, this was due to enhanced absorption of Zn by S amino acids at lower S intake, but ZnS precipitation was greater at higher S intake. Urinary Cu output decreased (quadratic, P<0.01), and metabolism of Mo was not altered ( P>0.10) by S supplementation. The models for SCu, SMo and SMoCu interactions proposed by Huisingh et al. (1973) were updated in view of these findings.