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. 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. 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.

中文翻译：

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不同来源的乙二胺四乙酸钠铁的化学特性及其对传统玉米-豆粕日粮饲喂肉鸡的相对生物利用度

我们之前的研究表明，具有较高络合或螯合强度的二价有机铁 (Fe) 蛋白源（以较大的形成商 (Qf) 值表示）对肉鸡显示出较高的 Fe 生物利用度。乙二胺四乙酸钠铁 (NaFeEDTA) 是一种三价有机铁源，具有最强的螯合配体 EDTA。然而，当以 NaFeEDTA 形式施用给肉鸡和其他农业动物时，铁的生物利用度尚未经过测试。在此，确定了 12 种 NaFeEDTA 产品的化学特性。其中，选择了一种饲料级NaFeEDTA（Qf = 2.07 × 108）、一种食品级NaFeEDTA（Qf = 3.31 × 108）和一种具有极强螯合强度的Fe蛋白盐（Fe-Prot ES，Qf值= 8,590） 。在第 1 至 21 天期间，通过研究上述铁源和添加铁水平对生长性能、血液学指数、肉鸡各组织中铁含量、含铁酶活性及基因表达。NaFeEDTA 来源的化学特性差异很大。血浆铁浓度（PI）、转铁蛋白饱和度（TS）、肝脏铁含量、肝脏、心脏和肾脏中的琥珀酸脱氢酶（SDH）活性、肝脏中的过氧化氢酶（CAT）活性以及肝脏和肾脏中的SDH mRNA表达量线性增加（ P < 0.05) 随着铁补充水平的增加。然而，不同Fe来源之间仅在PI、肝脏Fe含量、肝脏CAT活性、心脏和肾脏SDH活性以及肝脏和肾脏SDH mRNA表达量方面检测到差异（P < 0.05）。根据上述指标对每日日粮分析铁摄入量的多元线性回归斜率，肉鸡 Fe-Prot ES、饲料级 NaFeEDTA 和食品级 NaFeEDTA 相对于无机 FeSO4·7H2O (100%) 的平均生物利用度为分别为 139%、155% 和 166%。有机铁源相对于FeSO4·7H2O的生物利用度与其Qf值密切相关，并且Qf值较高的NaFeEDTA源对传统玉米-豆粕日粮饲喂的肉鸡表现出较高的铁生物利用度。