蛋氨酸锌在反刍动物上的利用

锌是动物体内必需的微量元素,是生物学功能研究最为深入的微量元素之一.目前,锌添加剂有3类：第一类是无机锌.     

微量元素锌的营养研究进展

锌是动物必需的微量元素之一,具有广泛的生理功能。文章从锌在动物体内的分布及代谢,锌对动物的生产性能、免疫和繁殖性能的影响等方面进行了阐述。     

锌与动物免疫功能的关系

动物免疫功能受体内外诸多因素的影响,近30年来,微量元素与免疫功能的关系越来越受到人们的重视,在微量元素中,目前锌与免疫功能关系的研究较为活跃。锌是动物生长和生命活动所必需的微量元素,其功能主要包括:锌是多     

微量元素锌和铜与免疫

锌、硒、铜、铬等作为动物必需的微量元素 ,在动物营养中已得到广泛的研究和应用。近些年有关微量元素对动物机体免疫作用的研究愈来愈受到关注。所谓免疫反应是指动物机体识别和清除抗原性物质 ,以维护机体内外环境相对稳定所发生的一系列反应。试验研究表明 ,合理的营养水平可保证动物各组织、器官功能处于最佳状态 ,强化动物的防御和免疫系统 ,增强动物对疾病的抵抗能力[1] 。本文主要论述了微量元素锌、铜在家畜免疫反应中的应用效果。1　锌与免疫锌是动物营养中必需的营养元素 ,不仅为维持动物机体生长发育所必需 ,而且也是动物免疫系…     

锌的分子生物学功能

锌是动物必需的重要微量元素，在机体代谢过程中起到重要的作用。作者综述了锌在动物繁殖、免疫、生长和脂肪代谢等方面的国内外最新研究进展。     

不同有机锌在动物生产中的研究

锌是动物机体必需的微量元素.与无机锌相比,有机锌具有化学稳定性好、生物利用率高和污染低的特点,是一种较理想的微量元素添加剂.     

锌营养作用的研究进展

ToddBertrand于1934年证明锌是动物必需微量元系之一.迄今为止已证明锌是动物体内功能最多的微量元素之一,与200多种酶的结构和生物学活性有关,参与动物体内三大物质、核酸和维生素以及微量元素等营养物质的代谢,从而影响动物的生长发育、繁殖和机体健康等,具有广泛的生理功能.……     

甘氨酸锌在动物生产中的应用研究

锌是动物体内的必需微量元素之一,在动物生长发育和健康方面起着关键作用。甘氨酸锌作为有机微量元素具有生物利用率高、减排环保等优势。综述了甘氨酸锌对动物的生长性能、繁殖性能、免疫能力及肠道健康的影响,探讨了动物对甘氨酸锌的需要量,旨在为动物生产中科学利用甘氨酸锌改善动物健康,促进动物生长提供理论依据。     

锌与畜禽免疫功能的关系

近年来，随着动物营养学的横向发展，已形成了营养与生理、营养与免疫、营养基因与调控等边缘学科，微量元素与免疫功能的关系也越来越受到人们的高度重视。锌是动物机体维持生命活动所必需的微量元素，动物体内有200多种酶含有锌，锌通过调节这些酶的活性来影响动物机体的代谢过程。本文就微量元素锌与动物细胞免疫、体液免疫和非特异性防循系统的关系进行综述。     

微量元素锌在反刍动物生产中的应用

锌是动物机体的必需微量元素之一,具有提高动物繁殖性能、生产性能和免疫功能等作用。本文就锌在反刍动物生产中的应用作一综述。     

Bioavailability of zinc in several sources of zinc oxide, zinc sulfate, and zinc metal.

Three zinc depletion-repletion assays were carried out with chicks to determine Zn bioavailability in five sources of ZnO, three sources of ZnSO4.H2O, and two sources of Zn metal. A standard 23% CP corn-soybean meal diet was fed during the first 3 d posthatching, after which it was replaced with a Zn-deficient soy concentrate diet (13.5 mg Zn/kg) until d 7. On d 8 after an overnight period of feed withdrawal, chicks were fed for 12 d the Zn-deficient basal diet containing 0, 4.76, and 9.90 (Assay 1); 0, 5.06, or 10.12 (Assay 2); or 0, 4.73, or 9.13 (Assay 3) mg/kg supplemental Zn from analytical grade (AG) ZnSO4.7H2O (22.7% Zn) to generate a standard response curve. The AG and feed-grade (FG) Zn sources being evaluated were then provided at a level that would fall within the standard curve. Weight gain (Assays 1, 2, and 3) and total tibia Zn (Assay 1) responded linearly (P<.01) to Zn supplementation from ZnSO4.7H2O. Weight gain regressed on supplemental Zn intake gave standard-curve equations with fits (r2) ranging from .94 to .97. In Assay 1, regression of total tibia Zn (Y, in micrograms) on supplemental Zn intake (X, in milligrams/12 d) gave the equation Y = 13.2+6.74X (r2 = .90). Standard-curve methodology was used to estimate relative Zn bioavailability (RBV), with RBV of Zn in the ZnSO4.7H2O standard set at 100%. Four sources of FG ZnO were evaluated: Source 1 (78.1% Zn, hydrosulfide process, U.S.), Source 2 (74.1% Zn, Waelz process, Mexico), Source 3 (69.4% Zn, China), and Source 4 (78.0% Zn, French process, Mexico). Analytical-grade ZnO (80.3% Zn) was also evaluated. Feed-grade ZnO Sources 1 and 4 as well as AG ZnO produced average RBV values that were not different (P>.10) from the standard, but average RBV values for FG Source 2 and FG Source 3 were only 34 (P<.05) and 46% (P<.05), respectively. All sources of ZnSO4.H2O, which included two FG sources (source 1, 36.5% Zn; source 2, 35.3% Zn) and one food-grade source (36.5% Zn), were not different (P>.10) in RBV from the ZnSO4.7H2O standard. Two Zn metal products, Zn metal dust (100% Zn) and Zn metal fume (91.5% Zn), were also evaluated, and they were found to have Zn RBV values of 67 (P<.05) and 36% (P<.05), respectively. Feed-grade sources of ZnO vary widely in color, texture, Zn content, and Zn bioavailability.     

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.     

Uptake of zinc from zinc sulfate and zinc proteinate by ovine ruminal and omasal epithelia

Uptake and transport of Zn from (65)Zn-labeled ZnSO(4) and Zn proteinate (ZnProt) by ruminal and omasal epithelia were examined by using a parabiotic chamber system. Uptake was measured during a 4-h incubation with 10, 20, or 200 microM Zn as ZnSO(4) or ZnProt in the mucosal buffer (pH 6.0, Krebs-Ringer phosphate). Zinc uptake and transport were also evaluated after simulated ruminal digestion. Buffered ruminal fluid contained a feed substrate and 10 or 200 microM added Zn as ZnSO(4) or ZnProt. In a preliminary experiment, uptake of Zn by omasal tissue was low; thus, the remaining experiments were conducted solely with ruminal epithelium. Incubations to determine the effect of time on Zn uptake from mucosal buffer containing 20 microM added Zn as ZnSO(4) or ZnProt resulted in increased (P < 0.01) Zn uptake as incubation time increased from 30 to 240 min. Zinc uptake was also greater (P = 0.02) from mucosal buffer containing ZnProt compared with ZnSO(4). Zinc uptake from incubations containing 10 or 200 microM was affected by source x concentration (P = 0.05) and concentration x time (P < 0.01) interactions. With 10 microM Zn, uptake was not influenced by Zn source, whereas when 200 microM Zn was added, Zn uptake from ZnProt was greater than from ZnSO(4). Increasing incubation time resulted in increased Zn uptake with 200 microM Zn in the mucosal buffer; however, with 10 microM Zn, uptake did not change after 30 min. After simulated ruminal fermentation, the proportion of Zn in a soluble form was influenced by a source x concentration interaction (P = 0.03). After 18 h of incubation, the proportion of Zn that was soluble was not different between ZnProt and ZnSO(4) in buffered ruminal fluid that contained 10 microM added Zn, but was greater for ZnProt compared with ZnSO(4) with 200 microM Zn in the incubation. Zinc uptake from the aqueous fractions of simulated ruminal digestions containing 200 microM added Zn was greater (P < 0.01) than from those containing 10 microM added Zn. Zinc transport, based on detection of (65)Zn in serosal buffer, did not occur in any of the experiments. The results of the current experiments suggest that absorption of Zn into the bloodstream does not occur from the ruminant foresto-mach; however, Zn uptake occurs in ruminal tissue and is greater from ZnProt than from ZnSO(4).     

锌的生物学功能及有机锌的应用研究

锌是动物的必需元素,在动物机体代谢过程中起着重要的作用.本文综述了锌的生物学功能及有机锌的应用研究,包括有机锌的种类及在动物营养中的应用,并预测了今后有机锌的研究方向.     

饲粮锌水平对肉鸡血锌、组织锌及含锌酶含量的影响

为研究饲粮中不同锌水平对某些含锌酶活性及血、胰和胫骨锌含量的影响,试验选择1日龄健康AA肉鸡公雏300只,随机分为5个处理组,各处理组锌的含量分别为30、60、90、120、150 mg/kg。结果表明:(1)21日龄时,120、150 mg/kg锌组血锌含量显著增加(P<0.05),与对照组相比,分别提高了56.75%和91.45%;150 mg/kg锌组胰锌含量显著增加(P<0.05),与对照组相比,提高了130.77%;90、120、150 mg/kg锌组胫骨锌含量显著增加(P<0.05),分别比对照组提高14.16%、19.50%和26.61%。42日龄时,150 mg/kg锌组血锌含量显著增加(P<0.05),比对照组提高77.25%;60、90、120 mg/kg锌组胰锌含量显著增加(P<0.05),分别比对照组提高194%、198%和212%;120、150 mg/kg锌组胫骨锌含量显著增加(P<0.05),分别比对照组提高37.80%和43.29%。(2)21日龄时,120、150 mg/kg锌组心肌金属硫蛋白(MT)含量显著增加,分别比对照组提高9.79%和32.17%;90、120、150 mg/kg锌组骨骼肌MT含量显著增加,分别比对照组提高54.55%、57.02%和90.91%。42日龄时,心肌和骨骼肌中的MT含量没有表现出显著的差异。(3)21日龄时,150 mg/kg锌组肝脏铜锌超氧化物歧化酶(CuZn-SOD)活性显著提高,42日龄时,150 mg/kg锌处理组肝脏CuZn-SOD活性显著低于其他处理组。在本试验条件下,饲粮中添加硫酸锌可以显著提高肉鸡血清、胰脏、胫骨组织中的锌沉积,并对肝脏CuZn-SOD活性有一定的影响。     

Effects of dietary supplementation with tribasic zinc sulfate or zinc sulfate on growth performance,zinc content and expression of zinc transporters in young pigs

An experiment was conducted to compare the effects of zinc sulfate (ZS) and tribasic zinc sulfate (TBZ) as sources of supplemental zinc on growth performance, serum zinc (Zn) content and messenger RNA (mRNA) expression of Zn transporters (ZnT1/ZnT2/ZnT5/ZIP4/DMT1) of young growing pigs. A total of 96 Duroc × Landrace × Yorkshire pigs were randomly allotted to two treatments and were fed a basal diet supplemented with 100 mg/kg Zn from either ZS or TBZ for 28 days. Feed : gain ratio in pigs fed TBZ were lower (P < 0.05) than pigs fed ZS, and average daily weight gain tended to increase (0.05 ≤ P ≤ 0.10) in pigs fed TBZ. Compared with pigs fed ZS, pigs fed TBZ had a higher CuZn‐superoxide dismutase and Zn content in serum (P < 0.05) while they had a lower Zn content in feces (P < 0.05). In addition, ZIP4 mRNA expression of zinc transporter in either duodenum or jejunum of pigs fed TBZ were higher (P < 0.05) than pigs fed ZS. These results indicate that TBZ is more effective in serum Zn accumulation and intestinal Zn absorption, and might be a potential substitute for ZS in young growing pigs.     

Excretion of zinc in lactating cows receiving various supply of zinc]

Studies were carried out with 5 lactating cows receiving a semisynthetic diet to trace the pattern of zinc excretion in the faeces, urine and milk under conditions of Zn depletion and repletion. Faecal Zn concentrations were found to be drastically reduced during a 6-week period of Zn depletion. The Zn supply to the animals at different levels of Zn repletion (varying between 22 mg and 436 mg Zn per kg) was well reflected in the corresponding faecal Zn concentrations. Similarly, faecal Zn excretion expressed as the percentage of Zn supplied with the diet was shown to change with the level of Zn supply. In the range between 6 mg and 54 m Zn per kg of dietary dry matter the level of relative faecal Zn excretion increased from 42% to 56% whereas with higher Zn supplements (up to 436 mg/kg) only slight increases (up to 60%) were observed. This indicates that the organism exhibits a strong tendency to maintain a physiological balance; this tendency is all the more pronounced with increasing Zn depletion; thus after 19 weeks of Zn depletion as little as 25% of the administered amount of Zn was excreted in the faeces. The average minimum of urinary Zn concentrations was 0.25 mg Zn per litre. The Zn concentrations in urine were not found to be dependent on the Zn supply. The level of relative Zn excretion in the milk was markedly increased despite the reduced concentrations of milk Zn during the periods of Zn deficiency. At the beginning of Zn depletion rather more zinc was released with the milk than was taken up with the Zn deficient diet. The mean proportion of milk Zn in the total amount of dietary Zn over the 6-week depletion period was 91%. With Zn amounts of 22 mg, 54 mg, 87 mg, 108 mg, 130 mg and 436 mg per kg of diet 23.7%, 13.1%, 12.9%, 5.7%, 4.3%, and 1.7% of the dietary Zn were excreted with the milk. Thus, a relative decrease of Zn excretion in the milk was observed, i.e. relative to the level of Zn supplementation.