Effect Of Dietary Iron Levels Research Articles

Dietary Iron Levels and Hypoxia Independently affect Iron Absorption in Mice

The effect of dietary iron levels on the hypoxic response of iron absorption was investigated by feeding mice diets of different iron composition and determining iron absorption. Eight groups of mice were fed a purified diet consisting of casein, corn oil and sucrose with vitamins and iron-free mineral supplements. Groups A–D were fed a nonpurified diet until 6 wk old and then switched to purified diet for 4 d. Groups E–H were fed purified diet for 4 wk from weaning. Groups C, D, G and H were exposed to hypoxia (53.3 kPa) for the last 3 d of the study. Groups A, C, E and G received the low iron purified diet (<1 mg iron per kg); the other groups received the same diet supplemented with 62 mg/kg iron as FeCl3·6H2O. Hypoxic exposure raised iron absorption (P < 0.001) by a similar proportion (2.5- to 5.0-fold) in all mice but did not affect duodenal nonheme iron levels. Low iron diet feeding raised iron absorption but reduced duodenal and liver nonheme iron levels. In a second experiment, mice fed nonpurified diet were divided into four groups and exposed to normal atmosphere or hypoxia (53.3 kPa) with or without dosing with 100 µg iron by stomach tube 1 h before determining iron absorption. There was no effect of iron dosing on iron absorption at either pressure. The data suggest that the control of iron absorption by tissue oxygen acts through a mechanism independent of the control exerted by dietary or mucosal iron levels.

Effects of dietary iron levels on growth performance, iron metabolism and antioxidant status in spotted seabass (Lateolabrax maculatus) reared at two temperatures

The increased ambient temperature is often accompanied by the enhanced metabolic rate and oxygen consumption of fish, which affects their nutritional requirements. Currently, no information compares the iron requirements of fish species under moderate and high temperatures. This study investigated the effects of dietary iron levels on growth performance, iron metabolism, and antioxidant status in spotted seabass (Lateolabrax maculatus) reared at two temperatures. Six diets were formulated to contain 63, 120, 188, 316, 425, and 554 mg/kg iron, each of which was fed to two groups of juveniles reared at 27°C (MT) and 33°C (HT) for 56 days. The results showed that the satisfied iron requirement for spotted seabass improved growth, feed utilization, and antioxidant capacity. Furthermore, fish fed with high‑iron diets prevented iron overload by repressing intestinal iron-regulatory proteins and inducing liver hepcidin production. Iron deficiency depressed erythropoiesis and worsened HT-induced hypoxic status. Moreover, the HT compromised fish growth, feed utilization and liver hepcidin expression, while inducing lipid deposition. Compared to 27°C, the iron demand of spotted seabass was increased at 33°C as more blood erythrocyte and tissue iron deposition were required. Based on the broken-line regression analysis of weight gain, the optimum dietary iron levels for spotted seabass reared at 27°C and 33°C were 178.5 and 209.0 mg/kg, respectively.

Evaluation of the optimum dietary iron level and its immunomodulatory effects on juvenile Chinese mitten crab, Eriocheir sinensis

This study evaluated the effects of dietary iron levels on growth, antioxidant status and non-specific immunity in juvenile Chinese mitten crab (Eriocheir sinensis). A 56-day feeding trial containing six experimental diets supplemented with six iron levels (0, 30, 60, 120, 240, 480 mg/kg) was conducted. The crabs fed the 177 mg/kg iron diet had significantly higher weight gain and specific growth rate and lower feed conversion ratio compared with those fed the 64 and 508 mg/kg iron diets. A positive correlation was observed between the iron content in the whole body and hepatopancreas with dietary iron supplementation. The catalase activities, total antioxidant capacity, superoxide dismutase and glutathione peroxidase in the hepatopancreas were significantly increased in 89–177 mg/kg iron diets. In addition, the non-specific immunity of the crabs was also improved with the increasing level of dietary iron supplementation (P < 0.05). Broken-line analysis on weight gain, specific growth rate and iron level in the hemolymph against dietary iron levels indicates that the optimal iron requirement for juvenile crabs ranged from 130 to 141 mg/kg. The transcription of iron regulatory protein had a decreasing trend while that of ferritin-1and ferritin-2 had an increasing trend regardless of the lipopolysaccharide and phosphate buffer saline treatment. The highest transcription of inflammation-related genes in the hepatopancreas was found in the crabs fed diets without iron supplementation under the lipopolysaccharide stimulation. Our results indicate that the optimal iron requirement for juvenile crabs was in the range of 130–141 mg/kg and dietary iron plays an indispensable role in the innate immune system in E. sinensis.

Effects of dietary iron level on growth performance, hematological status, and intestinal function in growing-finishing pigs.

This study investigated the different addition levels of iron (Fe) in growing-finishing pigs and the effect of different Fe levels on growth performance, hematological status, intestinal barrier function, and intestinal digestion. A total of 1,200 barrows and gilts ([Large White × Landrace] × Duroc) with average initial body weight (BW; 27.74 ± 0.28 kg) were housed in 40 pens of 30 pigs per pen (gilts and barrows in half), blocked by BW and gender, and fed five experimental diets (eight replicate pens per diet). The five experimental diets were control diet (basal diet with no FeSO4 supplementation), and the basal diet being supplemented with 150, 300, 450, or 600 mg/kg Fe as FeSO4 diets. The trial lasted for 100 d and was divided into the growing phase (27 to 60 kg of BW) for the first 50 d and the finishing phase (61 to 100 kg of BW) for the last 50 d. The basal diet was formulated with an Fe-free trace mineral premix and contained 203.36 mg/kg total dietary Fe in the growing phase and 216.71 mg/kg in the finishing phase based on ingredient contributions. And at the end of the experiment, eight pigs (four barrows and four gilts) were randomly selected from each treatment (selected one pig per pen) for digesta, blood, and intestinal samples collection. The results showed that the average daily feed intake (P = 0.025), average daily gain (P = 0.020), and BW (P = 0.019) increased linearly in the finishing phase of pigs fed with the diets containing Fe. On the other hand, supplementation with different Fe levels in the diet significantly increased serum iron and transferrin saturation concentrations (P < 0.05), goblet cell numbers of duodenal villous (P < 0.001), and MUC4 mRNA expression (P < 0.05). The apparent ileal digestibility (AID) of amino acids (AA) for pigs in the 450 and 600 mg/kg Fe groups was greater (P < 0.05) than for pigs in the control group. In conclusion, dietary supplementation with 450 to 600 mg/kg Fe improved the growth performance of pigs by changing hematological status and by enhancing intestinal goblet cell differentiation and AID of AA.

Effects of Dietary Iron Level on Growth Performance, Immune Organ Indices and Meat Quality in Chinese Yellow Broilers.

Simple SummaryIron (Fe) is an essential trace mineral for all living organisms, playing important roles in oxygen and electron transport as well as in DNA synthesis. At present, requirements of chickens for trace elements are still based on past National Research Council (NRC) (1994) standards. It is important, therefore, to accurately re-evaluate and satisfy the Fe requirements of modern broiler chicken, and especially important, non-Western breeds such as Chinese yellow broilers, for their optimal growth and health. Therefore, the aim of the present study was to investigate the effects of Fe on growth performance, immune organs and meat quality in Chinese yellow broilers. Based on the findings, feeding yellow-feathered broilers on a conventional corn-soy-based diet satisfies their requirements without additional Fe at ages 1 to 21, and 22 to 42 d, while 90 mg/kg in the finisher phase improved meat quality, and from the QP (quadratic polynomial) models of the key meat quality variables pH of breast muscle and drip loss of breast muscle, the optimal dietary Fe level was 89 to 108 mg/kg, and daily Fe fed allowance was 11 to 13 mg in the finisher phase (43 to 63 d).The objective of three trials was to investigate the effects of dietary Fe on growth performance, immune organ indices and meat quality of Chinese yellow broilers during the whole growth period. A total of 1440 1-day-old, 1440 22-day-old, and 1080 43-day-old Lingnan yellow male broilers were randomly assigned to one of six dietary treatments with six replicates per treatment (40 birds per replicate for both 1 to 21 d and 22 to 42 d, 30 birds for 43 to 63 d). Additional Fe (0, 20, 40, 60, 80, and 100 mg/kg) was added as FeSO4 • H2O to the three basal diets (calculated Fe 50 mg/kg, analyzed 48.3, 49.1, 48.7 mg/kg, respectively). The calculated final dietary Fe concentrations in Starter, Grower and Finisher phases were 50, 70, 90, 110, 130, and 150 mg/kg. The results showed that average daily gain (ADG), average daily feed intake (ADFI) and feed conversion rate (FCR) of the broilers were not influenced by the different levels of Fe (p> 0.05). Weight indices of the spleen, thymus and bursa of Fabricius were not influenced (p > 0.05) by the different levels of Fe during three 21-day experimental periods. Hematocrit, and Fe contents of the liver and kidney were not affected by different levels of Fe (p> 0.05). The diet with 150 mg/kg of Fe increased the a* (relative redness) value of breast muscle compared to the 50 and 70 mg/kg diets at 24 h post mortem (p< 0.05). The diet with 90 mg/kg Fe increased the pH of breast muscle compared to broilers fed 50 or 150 mg/kg Fe (p < 0.05) 45 min after slaughter. The diet with 90 mg/kg Fe decreased drip loss of breast muscle compared to 150 mg/kg Fe (p< 0.05). These data suggest that feeding yellow-feathered broilers on a conventional corn-soy based diet satisfies their requirements without additional Fe at ages 1 to 21, and 22 to 42 d, while 90 mg/kg in the finisher phase improved meat quality, and from the QP (quadratic polynomial) models of the key meat quality variables, pH of breast muscle and drip loss of breast muscle, the optimal dietary Fe level was 89 to 108 mg/kg, and daily Fe fed allowance was 11 to 13 mg in the finisher phase (43 to 63 d).

Effect of dietary iron levels on growth, iron concentration in tissues, and blood concentration levels of transferrin and hepcidin in bighead carp (Aristichthys nobilis)

A 60‐day feeding trial was conducted to estimate the effects of dietary iron (Fe) levels on growth, Fe concentration in the liver, spleen, and blood, and transferrin and hepcidin concentrations in the blood of bighead carp (Aristichthys nobilis). The six experimental diets were formulated to contain different Fe levels (0, 43.1, 84.2, 123.3, 162.2 and 203.1 mg/kg of dry diet) using ferrous sulphate (FeSO₄) as the source. The weight gain (WG) and the specific growth ratio (SGR) of A. nobilis fed with a dietary Fe level of 123.3 mg/kg were significantly higher than that of the 0 mg/kg Fe group (p liver > whole body. When the Fe dietary content increases to 162.2 mg/kg, the blood concentrations of Fe significantly decreased and thereafter increased, hepcidin significantly decreased and thereafter decreased, and transferrin significantly increased and thereafter decreased. The results indicate that the transferrin blood content significantly increased with decreasing hepcidin of up to 264.63 μg/ml content and thereafter decreased. It could be concluded that after transferrin saturation, hepcidin functions to maintain iron balance in the blood of A. nobilis by decreasing transferrin content.

Effect of Dietary Iron Levels on Tissues, Intestinal Digestive Enzyme Activity, and Muscle Nutrient Compositions of Juvenile Bighead Carp (Aristichthys nobilis)

A 60-day feeding trial was conducted to estimate the effects of dietary iron (Fe) levels on iron concentration in tissues, intestinal digestive enzyme activities, and muscle nutrient composition of bighead carp (Aristichthys nobilis). Six experimental diets were formulated to contain different Fe levels (0, 43.1, 84.2, 123.3, 162.2 and 203.1 mg/kg of dry diets) using ferrous sulfate (FeSO4) as the source. When Fe dietary content increased to 43.1 mg/kg, trypsin activity in the intestine significantly increased and thereafter decreased. Lipase and amylase activity in the intestine significantly increased with increasing dietary Fe levels up to 123.3 mg/kg diet and thereafter decreased. With lipase and amylase activity in the intestine as the main indicators, Fe content of 123.3 mg/kg was the most suitable dietary Fe level for A. nobilis. Crude protein content in the muscle of the 84.2 mg/kg Fe group was the highest in all groups. Results indicated that the appropriate levels of dietary Fe alter muscle nutrient composition of A. nobilis. Fe content in the muscle and vertebrae significantly increased with increasing dietary Fe levels up to 203.1 mg/kg diet. Fe contents in different tissues were as follows: Vertebra &gt;intestine &gt;muscle.

Effect of dietary iron levels on growth, body composition and intestinal enzyme activities of juvenile Jian carp (Cyprinus carpio var. Jian)

A 60-day feeding trial was carried out to investigate the effect of iron on growth, body composition and digestive enzyme activities. Diets with seven levels of iron (53.9, 90.0, 115.6, 146.1, 176.0, 215.8 and 266.0 mg iron kg−1 diet) were fed to Jian carp (initial weight 11.4 ± 0.0 g). Per cent weight gain (PWG), feed efficiency (FE) and protein efficiency ratio were the lowest in fish fed the basal diet (P < 0.05). Body protein content was increased with the increasing iron levels (P < 0.05), but moisture, lipid and ash of fish were not significantly affected by dietary iron levels (P > 0.05). Activities of trypsin, lipase, α-amylase, Na+, K+-ATPase, alkaline phosphatase and gamma-glutamyl transpeptidase were improved with increasing dietary iron levels. Serum iron were significantly enhanced with dietary iron levels up to 146.1 mg iron kg−1 diet, and plateaued. In conclusion, iron improved digestive enzyme activities of juvenile Jian carp and the dietary iron requirement for serum iron of juvenile Jian carp (11.4–64.0 g) was 147.4 mg iron kg−1 diet with ferrous fumarate as the iron source.

Effects of Dietary Iron Levels on Growth Performance, Hematological Status, Liver Mineral Concentration, Fecal Microflora, and Diarrhea Incidence in Weanling Pigs

An experiment was conducted in weanling pigs (Landrace x Yorkshire x Duroc) to evaluate the effects of dietary iron levels on growth performance, hematological status, liver mineral concentration, fecal microflora, and diarrhea incidence. One hundred and forty-four piglets (initial BW 5.96 +/- 0.93 kg) were randomly allotted to one of the four dietary treatments on the basis of their body weights. The basal diets for each phase (phase 1: days 0 to 14; phase 2: days 15 to 28) were formulated to contain minimal Fe and then supplemented with gradient levels of Fe (0, 50, 100, and 250 mg/kg) from ferrous sulfate. Feces were collected on days 14 and 28 and used for the analysis of microbial count and trace minerals. Eight piglets from each treatment (two piglets per pen) were bled at 0, 7, 14, 21, and 28 days to determine their hematological and plasma Fe status. In addition, two piglets from each pen (eight piglets per treatment) were killed at days 14 and 28 to determine liver mineral concentrations. Pigs fed supplemental 250 ppm Fe showed lowest overall average daily gain (linear, p = 0.036). Diarrhea incidence was linearly increased (p < 0.001) with supplemental Fe level. On days 14, coliform population in normal feces was increased (p = 0.036) linearly with supplemental Fe level, and there were higher (p = 0.043) coliform population and lower (p < 0.001) Bifidobacterium spp. in the diarrhea feces. Supplemental Fe linearly (p < 0.05) improved the total red blood cells, hemoglobin, plasma, and liver (p = 0.109) Fe status of pigs and also increased (linear and quadratic, p < 0.001) the fecal excretion of Fe on days 14 and 28. It is concluded that increasing the dietary iron levels in piglets improved their hematological status and liver Fe content; however, higher dietary Fe levels might also be associated with the increased diarrhea incidence.

The effect of dietary iron levels on changes in iron status and zinc-dependent enzyme activities in rats fed two levels of dietary zinc.

In order to determine the interrelationship between dietary iron and zinc levels, the effects of dietary iron levels (2, 10, 20, and 40 microg/g) on changes in iron and zinc status and zinc enzyme activities (aminolevulinic acid dehydratase ALA-D EC 4.2.1.24 and alkaline phosphatase ALK-P EC 3.1.3.1) in male Wistar rats were investigated using adequate and marginally deficient zinc diets (25 and 5 microg/g). When rats were fed 5 microg Zn/g diets, body weight gain and food intake remained unchanged at a Fe diet intake of 20 microg/g or greater. Similar tendencies were obtained for hemoglobin, hematocrit, plasma iron, and transferrin saturation. In contrast, liver, spleen, and femur iron concentrations increased gradually with increased iron intake. Feeding diets containing 25 microg Zn/g did not alter these parameters. The percentages of apparent iron absorption in both dietary zinc groups tended to increase with decreasing dietary iron and attained maximum levels at an Fe intake of 10 microg/g. However, In the case of rats fed Fe at concentrations of 2 microg/g Iron absorption decreased. Regardless of the dietary zinc level, rats fed diets with an Fe concentration of 2 microg/g had decreased zinc absorption and plasma ALK-P activity. However, ALA-D activity was not influenced by dietary iron.

Ferrous iron uptake by rat duodenal brush border membrane vesicles: Effects of dietary iron level and competing minerals (Zn +2, Mn +2, and Ca +2)

We sought to confirm a recent report that Fe +2 uptake into rat brush-border membrane vesicles is markedly increased by short-term consumption of iron-deficient diet, with no additional enhancement as the animal becomes functionally iron-deficient with continuing dietary Fe deprivation. In addition, we investigated whether previously observed in vivo absorption interactions of iron, zinc, and manganese occur in the brush border membrane vesicles uptake process, and whether short-term or long-term consumption of an iron-deficient diet affects the interaction at the uptake level. We did not observe any differences in Fe +2 uptake between normal and iron-deficient brush border membrane vesicles, even when the iron status contrast was intensified by feeding a high iron versus iron-deficient diet for 3 weeks. Equimolar Zn +2 and Mn +2 decreased Fe +2 uptake by 29 to 50% and 11 to 39%, respectively. Iron deficiency did not alter these effects. Equimolar Fe +2 decreased Zn +2 uptake by 13 to 22%. Calcium, included as a negative control, did not affect Fe +2 uptake. Thus, some competition between Fe +2 and similar divalent cations does occur at the level of the brush border membrane; the exact nature of this competition remains to be determined.

Effects of Level and Saturation of Fat and Iron Level and Type in the Diet on Iron Absorption and Utilization by the Rat

Two 2 × 2 × 2 factorial studies were done to examine the effects of dietary iron level (10 or 35 ppm), percent dietary fat (5 or 30%) and type of fat (safflower or coconut oil) on heme or nonheme iron absorption and other indices of iron status in rats (liver Fe, Hb, ΔHb). Rats were made moderately anemic (Hb 7.8 ± 0.7 g/dL) by feeding an iron-deficient diet and were then fed one of the 16 experimental diets. Test meals (100 µg Fe) labeled with 59Fe were fed after 5 d and 59Fe absorption determined by whole-body counting. Rats were killed after 5 wk and liver Fe, final Hb and ΔHb were determined. Nonheme iron was better absorbed than heme iron regardless of other dietary factors. Both heme iron absorption and nonheme iron absorption were higher when high (30%) rather than low (5%) dietary fat was fed. The type of fat had no effect. Rats fed both nonheme and heme iron had significantly higher Hb, ΔHb and liver iron when fed coconut oil, compared to safflower oil. Rats fed nonheme iron had higher liver Fe, but not Hb or ΔHb, when fed high rather than low dietary fat. Rats fed heme iron had higher Hb, ΔHb and liver Fe when fed high fat than low fat.

Effects of Dietary Iron Level on Gut Iron Levels and Iron Absorption in the Rat

The proposal that the iron content of the intestine is of critical importance in determining the rate of iron absorption was examined in Sprague-Dawley rats. The iron content of the rat gut was found to vary with the iron content of the diet but the relationship was not a linear one. The more proximal sections of the gut were more sensitive to dietary iron level than the distal portions. Rats fed stock ration had much lower proximal gut iron levels than rats fed purified diets of lower iron content. The iron content of the gut appeared to influence, within limits, the absorption of 59Fe from an isolated gut loop. When rats were transferred from a high iron diet to a low iron diet, a steady depletion of iron from the gut was accompanied by an increase of iron absorption which was maximum on the third to fifth day after the change of diet. In the reverse experiment, iron absorption was almost immediately depressed concomitant with the elevation of the gut iron level. The iron content of the mucosa did not appear to influence the entrance of the test dose of iron into the mucosa. Rather, the major point of mucosal regulation appeared to be the transfer of iron from the mucosa to the blood supply. The failure of a large dose of iron placed in the jejunum to influence immediately the absorption of 59Fe from a duodenal loop indicates that extra-mucosal (hormonal?) control of iron absorption is minimal or lacking.