Efficiency of inorganic and organic iron sources under iron depleted conditions in broilers

The chemical characteristics of different sodium iron ethylenediaminetetraacetate sources and their relative bioavailabilities for broilers fed with a conventional corn-soybean meal diet

BACKGROUND

Our previous studies demonstrated that divalent organic iron (Fe) proteinate sources with higher complexation or chelation strengths as expressed by the greater quotient of formation (Qf) values displayed higher Fe bioavailabilities for broilers. Sodium iron ethylenediaminetetraacetate (NaFeEDTA) is a trivalent organic Fe source with the strongest chelating ligand EDTA. However, the bioavailability of Fe when administered as NaFeEDTA in broilers and other agricultural animals remains untested. Herein, the chemical characteristics of 12 NaFeEDTA products were determined. Of these, one feed grade NaFeEDTA (Qf = 2.07 × 108), one food grade NaFeEDTA (Qf = 3.31 × 108), and one Fe proteinate with an extremely strong chelation strength (Fe-Prot ES, Qf value = 8,590) were selected. Their bioavailabilities relative to Fe sulfate (FeSO4·7H2O) for broilers fed with a conventional corn-soybean meal diet were evaluated during d 1 to 21 by investigating the effects of the above Fe sources and added Fe levels on the growth performance, hematological indices, Fe contents, activities and gene expressions of Fe-containing enzymes in various tissues of broilers.

RESULTS

NaFeEDTA sources varied greatly in their chemical characteristics. Plasma Fe concentration (PI), transferrin saturation (TS), liver Fe content, succinate dehydrogenase (SDH) activities in liver, heart, and kidney, catalase (CAT) activity in liver, and SDH mRNA expressions in liver and kidney increased linearly (P < 0.05) with increasing levels of Fe supplementation. However, differences among Fe sources were detected (P < 0.05) only for PI, liver Fe content, CAT activity in liver, SDH activities in heart and kidney, and SDH mRNA expressions in liver and kidney. Based on slope ratios from multiple linear regressions of the above indices on daily dietary analyzed Fe intake, the average bioavailabilities of Fe-Prot ES, feed grade NaFeEDTA, and food grade NaFeEDTA relative to the inorganic FeSO4·7H2O (100%) for broilers were 139%, 155%, and 166%, respectively.

CONCLUSIONS

The bioavailabilities of organic Fe sources relative to FeSO4·7H2O were closely related to their Qf values, and NaFeEDTA sources with higher Qf values showed higher Fe bioavailabilities for broilers fed with a conventional corn-soybean meal diet.

Leg disorders in broiler chickens: a review of current knowledge

Ensuring improved leg health is an important prerequisite for broilers to achieve optimal production performance and welfare status. Broiler leg disease is characterized by leg muscle weakness, leg bone deformation, joint cysts, arthritis, femoral head necrosis, and other symptoms that result in lameness or paralysis. These conditions significantly affect movement, feeding and broiler growth performance. Nowadays, the high incidence of leg abnormalities in broiler chickens has become an important issue that hampers the development of broiler farming. Therefore, it is imperative to prevent leg diseases and improve the health of broiler legs. This review mainly discusses the current prevalence of broiler leg diseases and describes the risk factors, diagnosis, and prevention of leg diseases to provide a scientific basis for addressing broiler leg health problems.

Iron requirements of broiler chickens as affected by supplemental phytase

Iron is routinely supplemented in broiler feeds intending to prevent dietary deficiencies. The present research was conducted with the objective of assessing Fe requirements of broilers when fed supplemental phytase. A total of 1,280 1-d-old male Cobb × Cobb 500 were distributed in a 2 × 5 factorial arrangement (phytase-supplemented feeds × 5 graded increases of supplemental Fe) in 80 battery cages, eight replications of eight chicks each. The trial was replicated once. Chicks were fed a Fe-deficient diet without phytase (Fe analyzed at 31.30 ± 3.79 mg/kg) from placement to 7 d and then randomly distributed into battery cages with corresponding dieting treatments with or without phytase and graded increases of supplemental Fe. Feeds were formulated with corn and soybean meal (SBM), laboratory-grade calcium carbonate, and phosphoric acid; therefore, the vast majority of dietary Fe originated from corn and SBM (analyzed diet had 53.3 ± 1.41 mg/kg Fe). Phytase was added in excess to the producer recommendation of 1,000 FYT (4,452 ± 487 FYT/kg analyzed) such that phytate degradation was expected to be maximized. Supplemental Fe was from laboratory-grade ferrous sulfate heptahydrate (FeSO47H2O) which was increasingly added to the feeds (analyzed Fe in the supplemented feeds were: 53.3 ± 1.41, 65.5 ± 0.59, 77.2 ± 1.97, 87.6 ± 1.72, 97.7 ± 1.33 mg/kg). There were no interactions between phytase and dietary Fe for any response throughout the study (P > 0.05). Supplementing phytase had no effects on Fe intake or Fe excretion, as well as on hematocrit (Ht), hemoglobin (Hb), ferritin, Fe contents in the liver or thigh muscle color (P > 0.05). However, phytase-supplemented feeds produced better live performance as well as higher ileal digestible energy and Fe digestibility (P < 0.05). No effects were found for dietary Fe in live performance at day 28 (P > 0.05). On the other hand, increasing dietary Fe led to linear increases in Fe retention and excretion, Fe contents in livers, as well as Ht and Hb at 14 d (P < 0.05). Quadratic responses (P < 0.05) were observed for Hb at 21 d, serum ferritin on days 14, 21, and 28 (maximum responses were 83.3, 104.0, 91.9, and 88.3 mg/kg Fe, respectively). In conclusion, supplementing Fe adding to a total of 97.7 mg/kg dietary Fe did not affect live performance traits. However, the average of Fe-related blood parameters was maximized at 91.9 mg/kg dietary Fe. Supplementing phytase provided a significant increase in Fe digestibility.

Effects of dietary organic or inorganic iron concentrations on productive performance, egg quality, blood measurements, and tissue iron concentrations in aged laying hens

The objective of the current experiment was to investigate the effects of dietary organic or inorganic iron (Fe) concentrations on productive performance, egg quality, blood measurements, and tissue Fe concentrations in aged laying hens. A total of three hundred fifty 60-week-old Hy-Line Brown laying hens were allotted to one of five dietary treatments with seven replicates. Each replicate had 10 consecutive cages. Organic Fe (Fe-Gly) or inorganic Fe (FeSO₄ ) was added to the basal diet at the levels of 100 or 200 mg/kg Fe. Diets were fed on an ad libitum basis for 6 weeks. Results indicated that supplementation of organic or inorganic Fe in diets increased (p < 0.05) eggshell color and feather Fe concentrations compared with no supplementation of Fe in diets. An interaction was found (p < 0.05) between Fe sources and supplemental levels in diets for egg weight, eggshell strength, and Haugh unit. Hens fed diets supplemented with organic Fe had greater (p < 0.05) eggshell color and hematocrit than those fed diets supplemented with inorganic Fe. In conclusion, dietary supplementation of organic Fe increases the eggshell color of aged laying hens. High supplemental levels of organic Fe in diets improve egg weight in aged laying hens.

Dietary supplementation of ferrous glycinate improves intestinal barrier function by modulating microbiota composition in Cherry Valley ducks

Ferrous glycinate (Fe-Gly) has been increasingly used as iron fortification in the diets of weaned piglets and broilers, but the effect of Fe-Gly on intestinal barrier function in meat ducks has not been well defined. This study therefore investigated the effect of Fe-Gly on apparent nutrient utilization, hematological indices, intestinal morphological parameters, intestinal barrier function and microbial composition in meat ducks. A total of 672 one-day-old Cherry Valley ducks were randomly divided into 6 treatments (8 replicates for each treatment and 14 ducks for each replicate) and fed diets with 0 (control), 30, 60, 90 and 120 mg/kg Fe-Gly or 120 mg/kg FeSO4 for 35 d. The results showed that diets supplemented with Fe-Gly significantly increased average daily gain (ADG), average daily feed intake (ADFI), hematocrit (HCT), mean cell volume (MCV), the apparent utilization of dry matter (DM) and metabolizable energy (ME), villus height (VH) and villus height-to-crypt depth ratio (V:C) (P < 0.05). Fe-Gly also significantly up-regulated barrier-related genes including zonula occludens-1 (ZO-1), zonula occludens-2 (ZO-2), mucin 2 (MUC2) and lysozyme (LYZ) (P < 0.05), and down-regulated the mRNA expression of claudin-2 (CLDN2) and occludin (OCLN) in the jejunum (P < 0.05). The 16S rRNA sequence analysis indicated that the diet with Fe-Gly had a higher relative abundance of Intestinimonas and Romboutsia (P < 0.05), which have an ability to produce short chain fatty acids (SCFAs), especially butyric acid. It also decreased the relative abundance of pathobiont, including Megamonas, Eubacterium_coprostanoligenes_group and Plebeius (P < 0.05). Additionally, diets supplemented with 120 mg/kg Fe-Gly significantly increased the apparent utilization of DM and ME (P < 0.05) and decreased the relative abundance of Megamonas_unclassified and Bacteroides_unclassified compared with those fed 120 mg/kg FeSO4 (P < 0.05). These results revealed that diets supplemented with Fe-Gly exerted a potent beneficial effect on physical, chemical, immune and microbial barriers, thereby improving the integrity of the intestinal structure, promoting the digestion and absorption of nutrients to a certain extent, and ultimately elevating the growth performance of ducks.

Research Note: Metabolic utilization of iron from different iron sources in primary cultured hepatocytes of broiler embryos

The present study was carried out to evaluate the effects of iron (Fe) sources and levels on the Fe concentration and expressions of iron-containing enzymes or protein in primary cultured hepatocytes of broiler embryos. The hepatocytes were incubated with 0, 0.25 and 0.50 mmol/L added Fe from either Fe sulfate, or 1 of 3 organic Fe chelates with weak (Fe-Met W), moderate (Fe-Pro M), or extremely strong (Fe-Pro ES) chelation strengths for 24 h. The results showed that all supplemental Fe treatments had higher (P < 0.05) Fe concentration, succinate dehydrogenase (SDH), CAT and ferritin heavy chain 1 (FTH1) mRNA levels than those in the control group. The hepatocytes incubated with Fe-Prot ES had lower (P < 0.009) Fe concentration than those incubated with Fe sulfate, Fe-Met W or Fe-Prot M. The SDH mRNA level was lower (P < 0.05) in Fe sulfate and Fe-Prot ES groups than in Fe-Prot M group. In conclusion, the Fe from Fe-Prot ES was less utilizable than Fe from Fe sulfate, Fe-Met W or Fe-Pro M in primary cultured hepatocytes of broiler embryos.

Metabolic utilization of intravenously injected iron from different iron sources in target tissues of broiler chickens

No information is available regarding the utilization of iron (Fe) from different Fe sources at a target tissue level. To detect differences in Fe metabolic utilization among Fe sources, the effect of intravenously injected Fe on growth performance, hematological indices, tissue Fe concentrations and Fe-containing enzyme activities and gene expressions of Fe-containing enzymes or protein in broilers was investigated. On d 22 post-hatching, a total of 432 male chickens were randomly allotted to 1 of 9 treatments in a completely randomized design. Chickens were injected with either a 0.9% (wt/vol) NaCl solution (control) or a 0.9% NaCl solution supplemented with Fe sulphate or 1 of 3 organic Fe sources. The 3 organic Fe sources were Fe chelates with weak (Fe-MetW), moderate (Fe-ProtM) or extremely strong (Fe-ProtES) chelation strength. The 2 Fe dosages were calculated according to the Fe absorbabilities of 10% and 20% every 2 d for a duration of 20 d. Iron injection did not affect (P > 0.05) ADFI, ADG or FCR during either 1 to 10 d or 11 to 20 d after injections. Hematocrit and Fe concentrations in the liver and kidney on d 10 after Fe injections, and Fe concentrations in the liver or pancreas and ferritin heavy-chain (FTH1) protein expression level in the liver or spleen on d 20 after Fe injections increased (P ≤ 0.05) as injected Fe dosages increased. When the injected Fe level was high at 20% Fe absorbability, the chickens injected with Fe-ProtES had lower (P < 0.001) liver or kidney Fe concentrations and spleen FTH1 protein levels than those injected with Fe-MetW or Fe-ProtM on d 20 after injections. And they had lower (P < 0.05) liver cytochrome C oxidase mRNA levels on d 20 after injections than those injected with Fe-MetW or Fe sulphate. The results from this study indicate that intravenously injected Fe from Fe-ProtES was the least utilizable and functioned in the sensitive target tissue less effectively than Fe from Fe sulfate, Fe-MetW or Fe-ProtM.

Ferric citrate is a safe and digestible source of iron in broilers and piglets

Background

Iron (Fe) is traditionally supplemented in poultry and swine diets using inorganic forms (e.g. sulfates, oxides). However, research suggests that organic sources are more beneficial due to greater bioavailability. In this paper, we present results from four studies aimed at assessing ferric citrate (CI-FER™, Akeso Biomedical Inc., Burlington, MA, USA) as a safe and effective source of Fe for broilers and piglets.

Methods

A total of four studies were performed in Germany following standard farming practices for each species. One study in day-old broiler chicks and one study in weaned piglets were designed as target animal safety studies where animals were randomly allocated to one of three treatment groups: a negative control group, the proposed dose group and a multifold dose group. Broilers and pigs were fed the experimental diets for 35 and 42 days, respectively. In each study, average daily feed intake, average daily weight gain and feed conversion ratio were measured, and blood samples were taken at study end for routine biochemistry and haematology. The other two studies were designed to evaluate different sources of dietary Fe for weaned piglets bred and managed under standard farm conditions. All piglets received routine Fe injections (200 mg Fe dextran, intramuscular) on day 3 of age, as well as the experimental diets for 42 days. In both studies, performance parameters were measured. In one study, Fe digestibility and serum Fe, superoxide dismutase and haptoglobin were also measured. In all studies, the general health status of the animals was monitored daily and all culls and mortality recorded. Each study followed a complete randomised block design.

Results

In broilers, ferric citrate was well tolerated up to 2,000 mg/kg feed (×10 the recommended inclusion rate) and no adverse effects on growth, blood parameters or mortality were observed. In piglets, ferric citrate was well tolerated up to 5,000 mg/kg feed (×10 the recommended inclusion rate) with no adverse effects on growth, blood parameters or mortality. In addition, piglets fed ferric citrate performed significantly better than animals fed the negative control diet (containing only endogenous Fe) and those fed inorganic forms of Fe. Moreover, piglets fed ferric citrate demonstrated improved Fe digestibility and improved oxidative status. Altogether, these findings show that ferric citrate is a safe and easily digestible source of dietary Fe for broilers and piglets.

Potential application of Fe-methionine as a feed supplement on improving the quality of broilers breast meat

A total of 250 one-day-old Ross 308 male chicks were used to investigate the effects of Fe-methionine (Fe-met) and iron sulfate (FeSO₄ .7H₂ O) on performance, mineral concentration, meat quality, and oxidative stability of breast. The feeding experiment was performed with five dietary groups including group I (basal diet [BD] + 80 mg/kg FeSO₄ ), group II (BD + 60 mg/kg FeSO₄  + 20 mg/kg Fe-met), group III (BD + 40 mg/kg FeSO₄  + 40 mg/kg Fe-met), group IV (BD + 20 mg/kg FeSO₄ + 60 mg/kg Fe-met), and group V (BD + 80 mg/kg Fe-met). The results showed that Fe and Cu content in the breast muscle increased by dietary supplementation of organic and inorganic iron from II to V groups. Dietary groups of II, IV, and V increased L* value and b* value of breast meat. Additionally, redness of breast meat enhanced linearly and quadratically by dietary supplementation of 80 mg/kg Fe as FeSO₄ . In addition, dietary supplementation Fe from II to V groups led to a significant increase in pHu at 24-h postmortem while it was negatively correlated with L* value of breast muscle. This study demonstrates that replacing FeSO₄ with Fe-Met could improve breast meat yield of broilers. Although 80 mg of Fe-Met improved the iron content of meat, it showed detrimental effects on the lipid oxidation of breast meat.

Broiler responses to ferrous sulfate at different time periods: a comprehensive research on qualitative parameters of breast meat

The objective of present study was to study the effects of dietary ferrous sulfate (FeSO4) and time periods on Fe deposition, nutrients composition, color indices, water-holding capacity and oxidative stability of breast meat in broilers. This experiment was performed by 450 broilers in a 3 × 3 factorial design with 3 levels of supplemental Fe (0, 40 and 80 mg/kg) and 3 time periods (total, T: from 1 to 42 days; grower and finisher, GF: from 11 to 42 days and finisher, F: from 25 to 42 days). The results showed that increasing the iron supplementation to 80 mg/kg increased the breast meat crude Protein. Adding 80 mg/kg of FeSO4 during the T period increased the iron content of breast meat compared to other dietary periods. Supplementation of 40 mg/kg FeSO4 during T and GF periods increased quadratically (P < 0.001) the L* value of meat compared to F period. Meat redness significantly increased by adding of 80 mg/kg iron into broiler diet. At 1 and 7 day postmortem, malondialdehyde (MDA) and total antioxidant capacity (T-AOC) of meat were measured for determination of lipid oxidation stability of tissue. Feeding 40 mg/kg Fe caused a higher MDA value at both time points compared to 0 mg/kg Fe (linear response). However, increasing the Fe level to 80 mg/kg decreased MDA of meat (quadratic response). Adding 40 mg/kg Fe increased T-AOC of meat at both time points. It was concluded that dietary supplementation of 80 mg/kg Fe during T period resulted in the higher Fe deposition and better oxidative stability of breast meat in broilers.

Effects of dietary supplementation of iron as sulphates or glycine chelates on the productive performance and concentrations of acute-phase proteins and iron in the serum and liver tissues of broiler chickens

The aim of the study was to determine the effects of inorganic (ferrous sulfate [FeSO4] and FeSO4 + phytase [FeSO4+F]) and organic forms of iron (ferrous glycine chelate [FeGly], Fe-Gly + phytase [Fe-Gly+F]) on the concentrations of C-reactive protein (CRP), serum amyloid A (SA), alpha- 1-acid glycoprotein (α-AGP), haptoglobin (Hp), transferrin (TRF) and iron in the blood and liver tissue of poultry. Ross 308 roosters were used in this study. The acute-phase protein (AP) levels in the chicken serum and liver tissues were assayed using the double-antibody sandwich ELISA kits for chickens. The iron levels in serum and liver samples were measured using flame atomic absorption spectrophotometry. The results showed that the serum and hepatic iron concentration in the chickens receiving Fe-Gly and Fe-Gly-F were significantly higher than those in the control group and in the chickens receiving iron in the form of sulphates. Further, serum CRP and SA concentrations were lower in the chickens from the supplemented groups than in those from the control. The hepatic CRP concentration was higher in the supplemented groups than in the control group. The serum and hepatic TRF concentration were highest in the chickens receiving FeSO4 and FeSO4-F. The hepatic Hp concentration was higher in the chickens receiving organic forms of iron than in the control chickens, whereas the serum Hp concentrations were similar across the groups. The highest α-1-AGP concentration was found in the livers of the chickens receiving Fe- Gly and Fe-Gly-F. Taken together, these findings suggest that iron had the most beneficial effects for poultry in terms of health, performance and immunity when added to the feed in the form of glycine chelate.

Nutritional significance of amino acids, vitamins and minerals as nutraceuticals in poultry production and health - a comprehensive review

Nutraceuticals have gained immense importance in poultry science recently considering the nutritional and beneficial health effects of their constituents. Besides providing nutritional requirements to birds, nutraceuticals have beneficial pharmacological effects, for example, they help in establishing normal physiological health status, prevent diseases and thereby improve production performance. Nutraceuticals include amino acids, vitamins, minerals, enzymes, etc. which are important for preventing oxidative stress, regulating the immune response and maintaining normal physiological, biochemical and homeostatic mechanisms. Nutraceuticals help in supplying nutrients in balanced amounts for supporting the optimal growth performance in modern poultry flocks, and as a dietary supplement can reduce the use of antibiotics. The application of antibiotic growth enhancers in poultry leads to the propagation of antibiotic-resistant microbes and drug residues; therefore, they have been restricted in many countries. Thus, there is a demand for natural feed additives that lead to the same growth enhancement without affecting the health. Nutraceuticals substances have an essential role in the development of the animals' normal physiological functions and in protecting them against infectious diseases. In this review, the uses of amino acids, vitamins and minerals as well as their mode of action in growth promotion and elevation of immune system are discussed.

Effect of iron glycine chelate supplementation on egg quality and egg iron enrichment in laying hens

This study was conducted to evaluate the effects of iron glycine chelate (Fe-Gly) on egg quality of laying hens. A total of 810 laying hens (HyLine Variety White, 26 wk old) were randomly assigned to 6 groups, and each group consisting of 135 hens (5 replicates of 27 hens each). Hens in the control group received a diet supplemented with 60 mg Fe/kg as FeSO4, whereas hens in the other 5 groups received diets supplemented with 0, 20, 40, 60, and 80 mg Fe/kg from Fe-Gly, respectively. The study showed that dietary Fe-Gly treatments influenced (P < 0.05) the internal egg quality (egg weight, Haugh unit, albumen height), compared with the control group. However, dietary Fe-Gly supplementation showed few effects on the ultrastructure of eggshell in this study. The group of 60 mg Fe/kg as Fe-Gly was promoted (P < 0.05) in succinate dehydrogenase levels of liver and spleen compared with the 0 mg Fe-Gly/kg group, whereas the control (Fe/kg as FeSO4) group has no differences compared with the 0 mg Fe-Gly/kg group. The concentrations of Fe in the eggshell, yolk, and albumen were increased with increasing concentrations of Fe-Gly, where Fe-Gly (60, 80 mg Fe/kg) had higher (P < 0.01) Fe concentration than the control in yolk and albumen. The Fe-Gly groups (60, 80 mg Fe/kg) were influenced (P < 0.05) in transferrin, divalent mental transport 1, and ferroportin 1, compared with the control (FeSO4). In conclusion, Fe-Gly (60 mg Fe/kg) improved egg quality and egg iron enrichment. In general, there were no significant differences between Fe-Gly (40) and the control group in albumen height, Haugh unit, Fe concentration in eggshell and yolk. It revealed that FeSO4 could be substituted by a lower concentration of Fe-Gly and Fe-Gly may be superior to FeSO4 for egg quality in laying hens.

Effects of hot melt extrusion processed nano-iron on growth performance, blood composition, and iron bioavailability in weanling pigs

This study was conducted to investigate the effects of hot melt extrusion (HME) nano-iron as an alternative for the common ferrous sulfate on iron (Fe) bioavailability, growth performance, nutrient digestibility, intestinal morphology, and intestinal microbiota of weanling pigs. A total of 200 piglets (Landrace × Yorkshire × Duroc) were randomly allotted to seven treatments on the basis of initial body weight (BW) and sex. Treatments were the INO100 (100 ppm Fe as FeSO₄), HME-Fe levels (50, 75, and 100 ppm nano-Fe as FeSO₄). ORG100 (100 ppm Fe as iron methionine). In phase 1, the HME50 pigs showed the lowest Fe content in feed and feces. Plasma Fe concentration was increased in HME100 and ORG100 pigs. In phase 2, there were significantly lower concentration of Fe in feed and feces of HME50 pigs (p < 0.01). A lower Fe concentration in the plasma and liver were observed in HME50 pigs compared with HME100 pigs. Concentration of red blood cell (RBC) was the lowest (p < 0.01) for HME50 pigs. During phase 2, the HME100, HME75, and ORG100 pigs showed a higher RBC and hemoglobin values compared with HME50 pigs. Digestibility of gross energy (GE) and crude protein (CP) were significantly higher in HME100 pigs compared with HME50 pigs. There was an increased (p < 0.01) villus height in the duodenum and jejunum of HME100 pigs compared with HME50 pigs. It is concluded that dietary Fe does not improve growth performance of weanling pigs; however, increasing the dietary iron concentration in weanling piglets increased the RBC and hemoglobin. In addition, the potential ability of HME to be used at a lower level (HME75) was observed.

Effect of Iron Supplementation on Growth Performance, Hematological Parameters, Nutrient Utilization, Organ Development, and Fe-Containing Enzyme Activity in Pekin Ducks

The current study was conducted with a mathematical model to investigate the appropriate iron supplementation by analyzing growth performance, hematological parameters, nutrient utilization, organ development, and Fe-containing enzyme activity in Pekin ducks. A total of 1120 ducks (1-day-old; 50.62 ± 0.20 g) were randomly allotted to seven groups with eight replicates of 20 ducks per replicate. Ducks were fed either a low-iron diet or basal diets supplemented with 0, 30, 60, 90, 120, and 150 mg Fe/kg from iron sulfate, respectively. The results showed that iron deficiency decreased body weight (BW), average daily gain (ADG), average daily feed intake (ADFI), red blood cell count (RBC), hemoglobin (Hb), hematocrit (Hct), mean cell volume (MCV), the apparent utilization of energy and dry matter, the weight of duodenum, jejunum, and ileum but increased feed conversion ratio (F/G) (P < 0.05). Meanwhile, birds in low-iron groups showed an increase in oxidative stress evidenced by the decreased catalase (CAT) activities and production of malonaldehyde (MDA) (P < 0.05). On the contrary, diets supplemented with iron significantly improved the growth performance, in different ages, and achieved the best values in group 4 which supplemented 60 mg Fe/kg (P < 0.05). Also, iron supplementation increased the apparent utilization of energy and dry matter but decreased the utilization of iron in ducks at 35 days of age (P < 0.05). Furthermore, the hematological and intestine Fe-containing enzyme activities were improved with iron up to an optimal level (P < 0.05) at 14 and 35 days. In conclusion, iron deficiency impaired growth performance, physiological indexes, nutrient utilization, and antioxidant system, while dietary 71.25~82.80 mg/kg iron for starter ducks and 75.00~89.41 mg/kg iron for grower ducks were suggested to improve growth performance.

Organic iron absorption by in situ ligated jejunal and ileal loops of broilers

The objective of this study was to determine the effect of organic and inorganic Fe sources on the Fe absorption and gene expression of Fe and amino acid transporters in the ligated jejunal and ileal segments of broilers. The in situ ligated jejunal and ileal loops from Fe-deficient broiler chicks (28-d-old) were perfused with Fe solutions containing 0, 3.58, or 7.16 mM Fe from one of the following Fe sources: Fe sulfate (FeSO4∙7H2O), the mixtures of FeSO4∙7H2O with either Met or Gly, Fe-Gly chelate, or three Fe-amino acid or protein chelates with weak, moderate or extremely strong chelation strengths (Fe-Met W, Fe-Pro M, or Fe-Pro ES), respectively, for up to 30 min. Iron absorption was increased (P < 0.0001) as the perfused Fe concentrations increased, and no differences (P > 0.07) were detected in the Fe absorption between the jejunum and ileum. Regardless of intestinal segments, Fe absorption was higher (P < 0.006) for Fe-Pro ES and Fe-Pro M than for FeSO4·7H2O, and for Fe-Pro ES than for Fe-Met W. Glycine but not Met supplementation increased (P < 0.03) the absorption of Fe as FeSO4. Regardless of Fe source, Fe addition inhibited (P < 0.05) the mRNA expressions of divalent metal transporter 1 (DMT1) in the jejunum and ileum, but enhanced (P < 0.05) the mRNA expressions of l-type amino transporter 1 (LAT1) and B0-type amino acid transporter 1 (B0AT1) in the jejunum and ileum. No differences (P > 0.05) among different Fe sources were observed in the mRNA expression levels of Fe and amino acid transporters in both the jejunum and the ileum. The mRNA expression levels of DMT1, ferroportin 1, B0AT1, or y+LAT1 were higher (P < 0.0001), but those of excitatory amino acid transporter 3, LAT1, or y+l-type amino transporter 2 were lower (P < 0.04) in the jejunum than in the ileum. The supplementation of inorganic or organic Fe had no effect (P > 0.14) on the protein expression levels of DMT1 and FPN1 in the jejunum and ileum. The above results indicate that organic Fe sources with stronger chelation strengths showed higher Fe absorption in the jejunum and ileum of broiler chicks. Glycine was more effective in facilitating Fe absorption than Met as a ligand. The mRNA expressions of Fe and amino acid transporters in the jejunum were different from those in the ileum. The DMT1, LAT1, and B0AT1 might be involved in the Fe absorption in the jejunum or ileum of broilers.

Effect of iron source on iron absorption and gene expression of iron transporters in the ligated duodenal loops of broilers

This experiment was conducted to investigate the effect of iron source on Fe absorption and the gene expression of divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1) in the ligated duodenal loops of broilers. The in situ ligated duodenal loops from Fe-deficient broiler chicks (28-d-old) were perfused with Fe solutions containing 0 to 14.33 mmol Fe/L from 1 of the following: Fe sulfate (FeSO∙7HO), Fe methionine with weak chelation strength (Fe-Met W; chelation strength is expressed as quotient of formation [Q] value, Q = 1.37), Fe proteinate with moderate chelation strength (Fe-Prot M; Q = 43.6), and Fe proteinate with extremely strong chelation strength (Fe-Prot ES; Q = 8,590) for up to 30 min. The gene expression of DMT1 and FPN1 in the duodenal loops from the control group and the groups treated with 3.58 mmol Fe/L from 1 of 4 Fe sources was analyzed. The absorption kinetics of Fe from different Fe sources in the duodenum followed a saturated carrier-dependent transport process. The maximum transport rate (J) values in the duodenum were greater ( < 0.03) for Fe-Prot ES and Fe-Prot M than for Fe-Met W and FeSO∙7HO. The Fe perfusion inhibited ( < 0.05) the mRNA expression of but enhanced ( < 0.0008) the mRNA expression of in the duodenum and had no effect ( > 0.14) on the protein expression levels of the 2 transporters. These results indicated that organic Fe sources with greater Q values showed higher Fe absorption; however, all Fe sources followed the same saturated carrier-dependent transport process in the duodenum, and DMT1 and FPN1 might participate in Fe absorption in the duodenum of broilers regardless of Fe source.

The chemical characteristics of organic iron sources and their relative bioavailabilities for broilers fed a conventional corn-soybean meal diet

Twenty-four organic Fe sources were evaluated by polarographic analysis and via solubility in buffers (pH 5 and 2) and deionized water. Organic Fe sources included 6 Fe-Met complexes (Fe-Met), 10 Fe-Gly complexes, 1 Fe-Lys complex, 4 Fe proteinates, and 3 Fe-AA complexes (Fe-AA). Sources varied considerably in chemical characteristics. Chelation strengths (quotient of formation [Q] values) ranged from weak (Q = 1.08) to extremely strong strength (Q = 8,590). A total of 1,170 1-d-old Arbor Acres male broilers were randomly allotted to 6 replicate cages (15 chicks/cage) for each of 13 treatments in a completely randomized design involving a 4 × 3 factorial arrangement of treatments (4 Fe sources × 3 added Fe levels) plus a control with no added Fe. Dietary treatments included a corn-soybean meal basal diet (control; 55.8 mg Fe/kg) and the basal diet supplemented with 20, 40, or 60 mg Fe/kg as iron sulfate (FeSO∙7HO); an Fe-Met with weak chelation strength (Fe-Met W; Q = 1.37; 14.7% Fe); an iron proteinate with moderate chelation strength (Fe-Prot M; Q = 43.6; 14.2% Fe); or an iron proteinate with extremely strong chelation strength (Fe-Prot ES; Q = 8,590; 10.2% Fe). The growth performance, Fe concentrations, hematological indices, and activities and gene expressions of 2 Fe-containing enzymes in tissues of broilers at 7, 14, and 21 d of age were determined in the present study. Transferrin saturation in plasma on 14 d; bone Fe on d 7 and 14; liver Fe on d 7, 14, and 21; kidney Fe on d 14; succinate dehydrogenase activities in the liver on d 21 and in the kidney on d 7 and 21; mRNA levels in the kidney and heart on d 14; and mRNA levels in the liver and kidney on d 21 linearly increased ( < 0.05) as added Fe levels increased. However, differences in bioavailabilities among Fe sources were detected ( < 0.05) only for the mRNA levels in the liver and kidney on d 21. Based on slope ratios from the multiple linear regression of mRNA level in the liver or kidney of broilers on d 21 on daily dietary analyzed Fe intake, the bioavailabilities of Fe-Met W, Fe-Prot M, and Fe-Prot ES relative to iron sulfate (100%) were 129 ( = 0.18), 164 ( < 0.003), and 174% ( < 0.001) or 102 ( = 0.95), 143 ( = 0.09), and 174% ( < 0.004), respectively. These results indicated that the relative bioavailabilities of organic Fe sources were closely related to their Q values and organic Fe sources with greater Q values showed higher Fe bioavailabilities.