动物肠道铁吸收、转运及其调节的分子机制

铁是动物必需的微量矿物元素,在机体内发挥氧气运输、电子传递、细胞增殖等重要的生物学功能。缺铁或铁过量均会对机体产生危害。肠道铁吸收是调节机体铁稳态的重要环节,目前已经清楚了解的铁吸收和转运机制包括肠黏膜细胞对铁的摄取、铁在细胞内的转移、铁经基底膜转运到血液并经血液循环供机体组织细胞利用等几个环节。本文拟对铁在动物体内的吸收、转运及相关调节分子机制进行综述。     

Iron deficiency anemia

Iron is essential to virtually all living organisms and is integral to multiple metabolic functions. The most important function is oxygen transport in hemoglobin. Iron deficiency anemia in dogs and cats is usually caused by chronic blood loss and can be discovered incidentally as animals may have adapted to the anemia. Severe iron deficiency is characterized by a microcytic, hypochromic, potentially severe anemia with a variable regenerative response. Iron metabolism and homeostasis will be reviewed, followed by a discussion of diagnostic testing and therapeutic recommendations for dogs and cats with iron deficiency anemia.     

氨基酸螯合铁在养猪生产中的应用研究进展

铁是动物必需的一种微量元素 ,从母乳中摄入的铁不能满足仔猪的正常需要 ,若无有效补铁途径 ,仔猪极易发生贫血 ,同时也易感染其它疾病。与无机铁和简单有机铁添加剂相比 ,氨基酸螯合铁具有生物学效价高、环境污染小、安全性高等优点。本文对氨基酸螯合铁的吸收机制、生物学效价、跟其它微量元素吸收的关系及其应用效果等方面作一综述     

氨基酸螯合铁的研究及应用进展

铁是人和动物机体生命活动必需的微量元素之一,它参与机体内血红蛋白、肌红蛋白以及多种氧化酶的合成与代谢,同时,与增强机体免疫力、提高动物繁殖力及生长发育各项指标等有着密切的联系。氨基酸螯合铁作为一种优质的有机铁源,因其吸收率高、生物学效价高、对环境污染小等优点而备受国内外研究者的关注。主要从氨基酸螯合铁在体内的吸收和代谢、生理功能以及在实践中的应用等方面进行阐述,以期为相关研究提供参考。     

有机铁在猪饲料中的应用研究进展

铁在猪饲料营养中是必需的重要微量元素之一。而有机铁是第3代新型饲料添加剂,具有生物利用率高、化学结构稳定、增强免疫力、吸收率高、利于环保等特点,是当前国内外研制和开发的热点。作者综述了有机铁的生化特性、功能作用、吸收机理、生产应用和研究进展。     

幼龄动物铁吸收及其调控

哺乳动物机体内铁稳态的维持对生长发育非常重要,尤其是在幼龄快速生长阶段.铁的缺乏不仅严重影响幼龄动物的生长性能,而且会给中枢神经系统带来不可逆的损伤;但是机体铁过量也将对幼龄动物造成氧化应激并产生长期的副作用.动物机体在成年阶段对铁吸收过程能够精准地调控,但在幼龄阶段其铁调控功能并不成熟.幼龄动物小肠铁吸收的效率非常高,因此,对幼龄动物补铁需要慎重.本文就幼龄动物铁的吸收及其调控特点做一综述.     

Nickel content in the milk of lactating rats under intake of various amounts of nickel]

Model experiments were carried out with rats showing that the average Ni concentrations in the milk of the experimental animals receiving a Ni deficient diet (40 ppb of dietary Ni), relative to those of the controls (20 ppm), declined from 1088 ng/g to 726 ng/g (33%). This produced a Ni deficiency in the youngs of the rats resulting in retarded growth, reduced Fe absorption and a decline in enzymatic activity. An increase in the Ni content of the milk from both the experimental animals and the controls was observed during lactation. In the Ni deficient group this upward trend was longer noticeable from about the middle of the lactation period onwards. Animals in the Ni deficient group excreted about three times as much Ni through the milk as was ingested with the food. Because of the wide range of deviations of the Ni content in the different animals the Ni content of the milk cannot be used, under practical conditions, as an index of a state of Ni deficiency.     

Experimental bovine group-B streptococcal mastitis induced by strains of human and bovine origin

Intramammary infections with Group-B streptococci of human and bovine origin were produced experimentally in cows. The initial cytological response was more rapid to the human than to the bovine strain (Table I), while at later stages the pathological changes induced by the two infections were much the same (Fig. 1). The initial clinical reaction was more acute to the "human" than to the "bovine" infections and the average daily loss of milk was greater in cases of "human" infection than in cases of "bovine" infection (Table II). In contrast to the "bovine" infections the "human" infections showed a pronounced tendency to spontaneous clearance. The rate of excretion of Group-B streptococci with the milk was lower for the "human" than for the "bovine" infections (Table III). The special mode of reaction of the bovine udder against infections with Group-B streptococci of human origin may, in part, explain why such infections have a lower tendency to spread within a herd than infections with bovine strains of B-streptococci.     

Vitamin B12 Supplementation to Mink (Mustela vison) in the Prevention of Feed-Induced Iron Deficiency Anaemia: I. Effect on Growth Performance and Fur Quality Characteristics

Abstract

Vitamin B₁₂ supplementation in the prevention of feed-induced iron deficiency anaemia was evaluated with six treatment groups of mink kits, comprising a control group and five groups fed an anaemiogenic diet either unsupplemented, supplemented with vitamin B₁₂ orally, or by intramuscular injection, with iron therapy by ferrous fumarate and cysteine, and iron therapy plus vitamin B₁₂ orally. Unsupplemented animals showed symptoms of anaemia including poor growth performance, achromotrichia and poor fur quality. Oral vitamin B₁₂ supplementation, but not injections, had some effect in preventing anaemia, indicating an influence on intestinal iron absorption. Iron therapy completely prevented the occurrence of anaemia, and simultaneous addition of vitamin B₁₂ had no further positive effect.     

Iron homeostasis and disorders in dogs and cats: a review

Iron is an essential element for nearly all living organisms and disruption of iron homeostasis can lead to a number of clinical manifestations. Iron is used in the formation of both hemoglobin and myoglobin, as well as numerous enzyme systems of the body. Disorders of iron in the body include iron deficiency anemia, anemia of inflammatory disease, and iron overload. This article reviews normal iron metabolism, disease syndromes of iron imbalance, diagnostic testing, and treatment of either iron deficiency or excess. Recent advances in diagnosing iron deficiency using reticulocyte indices are reviewed.     

Impairment of the peripheral lymphoid compartment in iron-deficient piglets

The aim of this study was to investigate the effect of neonatal iron deficiency on immune functions in young piglets. While control piglets were not given any iron preparation until the age of 21 days, another group of piglets was given 200 mg of Fe(3+)-dextran i.m. on day 3. Red blood cell parameters in the former, iron-deficient group were characteristic of hypochromic anaemia. In addition, the total leucocyte count (P < 0.01), relative and absolute neutrophil count (P < 0.01) and absolute lymphocyte count (P < 0.05) in peripheral blood were found significantly lower in iron-deficient piglets than in their iron-supplemented counterparts. Lymphocyte activity as measured by in vitro lymphocyte transformation test was impaired in iron-deficient piglets. A statistically significant decrease in circulating B-lymphocyte numbers was found in non-supplemented animals. Iron deficiency apparently negatively influenced the immunocompetence in piglets.     

肠道细胞中铁、锌吸收与DMT-1相互关系的研究进展

铁、锌是动物重要的微量元素,对维持机体正常代谢起着关键的作用,其过量和缺乏都会对机体产生极大危害。本文综述了铁和锌吸收的相互作用、铁和锌吸收与DMT-1的相互关系以及影响铁锌吸收的其它因素,提出肠道细胞对铁、锌吸收的相互竞争,而这种竞争并非发生在DMT-1这一位点。     

Effect of iodine, copper and zinc supplements to rations with a high quota of rapeseed extract meal on the growth and thyroid function of fattening swine. 2. The effect of the iodine supplement on nutrient digestibility and on protein and energy retention

Three groups of six pigs each (live weight at the beginning of the experiment 20 kg) were given a cereal ration with 8% rape seed meal. Group I did not receive a J supplement and was fed ad libitum. The rations of groups II and III were supplemented with 1 mg J/kg feed. The feed intake of group II was limited to the amount consumed by group I (pair fed); group III received the feed ad libitum. The daily weight gains of the 3 groups were 327, 377 and 613 g, feed expenditure 3.79, 3.68 and 3.47 kg/kg gain. In an N balance experiment carried out with 3 animals each from groups I and II, 41.4% of the N taken in group I and 43.8% in group II were retained (p greater than 0.05). Liver, intestinal fat and leaf were heavier in group I (p less than 0.01), the protein content of the empty body, the bones and bristles significantly lower than in group II. Protein retention in group II was 14% higher than in group I. In case of iodine deficiency protein retention is lower, energy retention, however, is largely unchanged.     

氨基酸铁在大鼠小肠中的吸收及组织中沉积研究

本试验用50日龄Wistar纯系雄性大鼠,采用体内原位结扎肠段灌注技术和放射性同位素示踪技术,研究了氯基酸螯合铁(以赖氨酸螯合铁和甘氨酸螯合铁为代表)的吸收特点。试验中观察了向结扎肠段灌注含不同形态铁的吸收液后,不同时间点(5、15、30、60、90、120分钟)血液中59Fe比放射性的动态变化;120分钟(试验结束)时不同组织器官中59Fe的放射性大小和总铁含量以及主要血液学指标的变化。试验结果表明:①赖氨酸和甘氨酸都能促进大鼠对铁的吸收。②与相应摩尔浓度的氨基酸与氯化亚铁的混合物相比,赖氨酸螯合铁和甘氨酸螯合铁能更有效地被大鼠吸收。综合分析本试验结果认为,氨基酸螯合铁都是一种优秀的铁添加剂。从本试验结果看,放射性同位素示踪技术结合结扎十二指肠段灌注技术不失为一种研究动物对微量元素吸收情况的理想试验手段。     

丁酸钠对肉鸡肠道形态与消化吸收功能影响的研究进展

肠道是肉鸡重要的消化、内分泌及免疫器官，肠道健康主要依赖于营养物质、微生物菌群和肠道黏膜之间的动态平衡。肠道消化吸收功能与肠黏膜上皮细胞的生长及肠道形态结构的完整性直接相关。研究表明，丁酸钠作为能量来源，可刺激肉鸡肠道上皮细胞增殖并改善肠道黏膜形态，促进绒毛生长和肠道组织发育。丁酸钠通过肠道游离脂肪酸受体FFAR2和FFAR3介导肠道内分泌细胞分泌多种激素，促进胃肠黏膜的发育，刺激胃和胰腺分泌消化酶，促进养分消化吸收。丁酸钠是肠道稳态的重要调节因子，可刺激黏蛋白的产生，增加黏液层厚度，降低结肠上皮的通透性，维持肠道完整性和黏膜屏障功能。丁酸钠促进宿主防御肽（HPDs）的合成，抑制肠道内有害菌的增殖，降低内毒素对肠黏膜上皮细胞的损伤。丁酸钠通过抑制NF-κB激酶（IKK）下调促炎症途径，抑制NF-κB的活化，预防肠黏膜炎症发生，进而促进消化吸收和保护肠道健康。综上，丁酸钠具有肠道保护和抗菌作用，可增强肠道完整性，促进营养物质的消化吸收，提高免疫力和抗病力。在饲料工业禁抗的背景下，对抗生素替代品丁酸钠的研究和应用非常重要，作者就丁酸钠对肠道功能的作用机制进行重点阐述，以期为其在肉鸡饲料中替代抗生素提供科学依据。     

影响铁吸收利用因素研究进展

本文对动物体对铁的吸收利用的众多因素的影响进行了综述。近来的研究表明 ,动物的品种、年龄、机体铁贮和胃肠道环境影响对铁的吸收利用 ;动物所采食饲料的种类、铁含量以及饲料中所含的某些因子也影响动物对铁的吸收利用 ;动物对饲料中不同价态、不同存在形式铁的吸收利用有很大差别。     

乳源生物活性肽对动物肠道功能的影响及作用机制

乳源生物活性肽(MDBPs)是指乳汁中存在的参与机体多种代谢途径和生理环节,具有特殊氨基酸排列和空间结构的相对较短的小分子肽段。近年的研究发现MDBPs能影响动物肠道黏膜营养物质吸收、减缓肠道氧化应激、改善肠道微生态环境以及提高肠道免疫力。本文将围绕MDBPs对动物肠道功能的影响及作用机制进行综述。     

大肠埃希氏菌致东北虎子宫内膜炎的诊治

大肠埃希氏菌（E．coli）是人和动物肠道后段的常住菌，为条件致病菌，在动物机体免疫抵抗能力不足的情况下易诱发子宫内膜炎。在兽医临床上多以剧烈呕吐、腹泻等胃肠道症状出现，单纯以生殖道感染的报道很少见。     

Effects of different iron contents in the milk replacer on the development of iron deficiency anaemia in veal calves.

The effect of different iron concentrations in the milk replacer on the development of iron deficiency anaemia during a fattening period of 28 weeks was studied in three groups of 14 calves. The iron contents in the milk replacer differed during the first seven weeks: 60, 100 and 150 mg Fe/kg in groups A, B and C, respectively. In all three groups blood haemoglobin, mean corpuscular volume, plasma iron concentration and saturation decreased during the fattening period, whereas the total iron-binding capacity increased. At week 7, liver iron concentrations were high with a large individual variation [A: 201 (61-706), B: 99 (47-129), C: 296 (77-1572) micrograms/g dry matter]. During the fattening period, liver iron concentrations decreased, with the lowest values at week 25 [A: 54 (34-82), B: 55 (44-83), C: 57 (42-79) micrograms/g dry matter]. Muscle iron concentrations decreased between week 7 and 19. Except plasma iron and saturation in group C, no differences in haematological and tissue iron variables were found throughout the fattening period in spite of different iron contents in the milk replacer during the first seven weeks.     

日粮铁缺乏对肉仔鸡机体抗氧化功能影响的研究

１日龄艾维茵肉仔鸡１００只,随机分为２组,每组设有重复,自由采食以玉米、淀粉、葡萄糖和大豆分离蛋白为主日粮,日粮中分别添加０（铁缺乏组）和１１０ｍｇ／ｋｇ铁（对照组）,饮用去离子水,分别于１和１４日龄皮下接种ＨＶＴ冻干苗、７和１４日龄滴鼻接种Ｌａｓｏｔａ系冻干苗。试验结果表明,肉仔鸡疫苗接种及饲养管理同前。铁缺乏组与对照组相比：４２日龄肝脏、胸腺、脾脏和法氏囊中过氧化氢酶（ＣＡＴ）活性显著降低（Ｐ＜０．０５）、肝脏、胸腺和脾脏中谷胱甘肽过氯化物酶（ＧＳＨ－Ｐｘ）活性显著降低（Ｐ＜０．０５）;４２日龄肝脏、胸腺、脾脏和法氏囊中脂质过氧化物（ＬＰＯ）含量显著升高（Ｐ＜０．０５）。铁营养状况与机体抗氧化功能密切相关,日粮铁缺乏机体抗氧化功能降低。