产蛋鸡血浆卵黄前体物及其受体研究进展

在雌激素作用下,产蛋鸡肝脏合成卵黄前体物,即极低密度脂蛋白(VLDL)和卵黄生成素(VTG),二者分别为卵母细胞生长发育提供能量和营养物质.血浆卵黄前体物水平与蛋鸡生产性能密切相关.卵母细胞卵黄生成受体(OVR)介导卵黄前体物被产蛋鸡吸收,转运到生长中的卵母细胞,是卵黄前体物进入卵母细胞的瓶颈,其内吞VLDL的数量是蛋黄胆固醇含量的决定因素.本文综述了卵黄前体物及其受体类型、结构及其与产蛋鸡生产性能和蛋品质的关系.     

产蛋鸡卵母细胞卵黄生成受体(OVR)的研究进展

OVR介导大量的血浆蛋白被产蛋鸡吸收到生长的卵母细胞中,是卵黄前体进入卵母细胞的瓶颈。到目前为止发现它不仅与最丰富、最重要的卵黄前体极低密度脂蛋白(VLDL)、卵黄蛋白原(VTG)结合,还结合丛生蛋白、α2-巨球蛋白(α2-M)、受体相关蛋白(RAP)、乳铁蛋白、核黄素结合蛋白(ribBP)等,这些成分占蛋黄干物质的绝大部分。OVR发生突变的蛋鸡,不能繁殖,并且具有严重的高脂血症。它所内吞的VLDL的数量是蛋黄胆固醇含量的决定因素,因此期望通过调控OVR来控制蛋黄胆固醇的含量。     

产蛋鸡极低密度脂蛋白Y的转运与沉积机理

蛋鸡开产以后,在雌激素作用下,肝脏将由合成普通型极低密度脂蛋白(VLDL)转向大量合成极低密度脂蛋白Y(VLDLy),VLDLy颗粒小,富含甘油三酯、磷脂和胆固醇酯。载脂蛋白VLDL-Ⅱ(apoVLDL-Ⅱ)和载脂蛋白B100(apo-B100)是VLDLy主要的两种载脂蛋白,也受雌激素调控,是VLDLy正确组装所必需的。apoVLDL-Ⅱ是脂蛋白脂酶(LPL)的抑制剂,可以防止VLDLy被降解。这样,VLDLy就可以顺利地通过由卵黄生成素受体(OVR)介导的内吞作用完整地转运进入生长中的卵母细胞。在与受体结合的过程中,OVR的配体结合域LBR1～LBR3起到了关键的作用。可望通过调控apoVLDL-Ⅱ、apo-B100和OVR的基因表达来调控VLDLy的代谢。     

家禽卵泡发育与调控机制研究进展

禽蛋的主要营养都集中在蛋黄,而蛋黄在禽类体内由卵泡发育而来,形成过程分为多个阶段,主要包括前期卵母细胞的激活以及后期的卵黄快速沉积.从卵母细胞到成熟卵泡的发育过程中,需要吸收大量卵黄蛋白原(VTG)和极低密度脂蛋白(VLDL)等营养物质,以保障卵泡的正常发育,期间主要受到性腺激素、日粮以及相关通路的调节.文章阐述了家禽...     

鱼体的脂类运输（续）

1.6 鱼类脂蛋白的基因调控 鱼类脂蛋白不仅密度、大小和组成部分比例是不均一的,而且载脂蛋白部分的组成也不同,载脂蛋白是脂蛋白中唯一具有化学和免疫学独立特性的组成部分.其中,VLDL主要由载脂蛋白B(apo B)组成,也包括apo A-II和apo C.LDL主要含apo B,而HDL主要含apo A-I,其次是apo A-II.apo AI-1作为血清HDL中的主要组成蛋白,是LCAT潜在的激活因子,有利于血清中游离脂肪酸的去除.大西洋鲑肝和肌肉表达的是apo A-I的前体,而apo A-I的表达在小肠内才显现出来.apo C-II作为LPL的激活辅因子,在血清脂蛋白代谢中发挥重要作用.Yan Shen等(2000)对虹鳟的apo C-II序列测定发现,apo C-II存在于所有的脂蛋白中,包括LDL,10 ℃时虹鳟的血清比人类的血清对LPL表现出更高的激活能力,因此,虹鳟apo C-II的表达受外界条件(如温度)的影响较大.     

家禽脂肪酸代谢及其在禽蛋中的沉积和营养调控

在肝脏中载脂蛋白作用下,内源合成或外源获取的脂肪酸以甘油三酯的形式同胆固醇及其他脂类组装形成极低密度脂蛋白(VLDL)。VLDL经血液循环到达卵巢,穿过卵母细胞外层屏障后,经卵母细胞受体介导的内吞作用进入卵母细胞发生沉积。而机体的营养状况或饲粮中营养成分的改变可通过影响脂肪酸的从头合成或VLDL结构直接或间接影响禽蛋中脂肪酸的最终沉积。本文阐述了家禽体内脂肪酸的来源、转运与沉积过程,并探讨了脂肪酸代谢及其在禽蛋中沉积的营养调控。     

ApoB100对肝脏VLDL合成分泌的影响及其在兽医临床中的研究进展

肝脏可从循环中获得脂质,进行合成并将脂质中的脂蛋白分泌至血液中,在全身新陈代谢的动态平衡中起到核心作用。极低密度脂蛋白（VLDL）是肝脏的主要分泌产物,其主要作用是向外周组织运输内源性合成的脂类,如甘油三酯（TG）等。载脂蛋白B100 (ApoB100)作为VLDL颗粒中主要和必需的蛋白质,与大多数肝脏分泌蛋白的合成不同,主要由共降解和翻译后降解进行调节。文章就ApoB100通过降解及自噬作用影响奶牛肝脏VLDL的合成分泌以及ApoB100在兽医临床中的相关研究进行概述,以期为未来的相关研究提供参考。     

鸡蛋中的胆固醇为什么难以降低

出于对人类饮食中胆固醇含量的关注,人们作了种种努力来降低鸡蛋中的胆固醇含量,如通过遗传选择,改变蛋鸡饲粮或应用降胆固醇药物。尽管也有几个引人注目的例子,但绝大多数文献报道都表明,蛋黄中的胆固醇含嚣很难降低。本文阐述了蛋黄中胆固醇的沉积机制,以解释为什么蛋黄胆固醇难以降低? 蛋黄中的大部分胆固醇(>90％)以游离胆固醇的形式(非酯化)存在于蛋黄的脂蛋白中,它们在雌激素的刺激下予蛋鸡的肝脏中合成然后由     

脂肪代谢调控及其在改善鸡蛋品质中的应用

本文综述了前人利用胆固醇和多不饱和脂肪酸(PUFA)在蛋鸡体内的代谢和调控机制开发保健蛋以及提高鸡蛋品质方面的研究成果,即通过对营养代谢途径的调控来降低蛋黄中胆固醇含量、增加蛋黄中PUFA含量、改善蛋黄色度等。同时,结合现代生物技术和微生态营养调控技术,试图为开发具有降低蛋黄胆固醇含量、改善蛋黄色度以及提高蛋黄PUFA含量的饲料添加剂提供理论依据。     

高能量低蛋白质日粮对蛋鸡载脂蛋白AⅠ和脂质代谢的影响

本试验旨在研究高能量低蛋白质日粮对蛋鸡载脂蛋白A Ⅰ(apo A Ⅰ)和脂质代谢的影响.选用140日龄健康海兰褐壳蛋鸡102羽,随机分为2组,对照组日粮代谢能与粗蛋白质含晕分别为11.51 MJ/kg和15.58%,试验组日粮代谢能与粗蛋白质含量分别为14.47 MJ/kg和12.55%,每组设3个重复,每个重复17羽.于试验期第1天、第15天、第25天、第35天、第45天和第55天,每组取6羽采血制备血清和采集肝脏样品,测定血清apo A Ⅰ含量和与脂质代谢相关的指标.结果表明,与对照组相比,试验组血清甘油三酯和低密度脂蛋白胆固醇浓度分别从第35天和第45天起显著升高(P<0.05,P<0.01),第45天起高密度脂蛋白胆固醇显著降低(P<0.05);试验组血清和肝脏匀浆中脂肪酶活性第25天和第35天起显著升高(P<0.05,P<0.01),脂蛋白脂酶活力第45天和第35天起显著升高(P<0.05,P<0.01);试验组血清和肝脏匀浆中游离脂肪酸含量升高,从25天起与对照组差异极最著(P<0.01);第35天开始试验组血清apo A Ⅰ含量显著下降(P<0.05).结果提示,高能量低蛋白质日粮能降低产蛋鸡血清apo AⅠ含量,促进肝脂的蓄积,导致产蛋鸡脂质代谢平衡破坏.     

Effects of supplemental copper and chromium on the serum and egg traits of laying hens

1. This study investigated the effects of supplemental copper and chromium on the serum and egg traits of laying hens using 144 forty-five-week-old White Leghorn layers. The hens were randomly assigned into 9 groups to conduct this 3 copper (0, 125 and 250 mg/kg as copper sulphate) x 3 chromium (0, 800 and 1600 microg/kg as chromium picolinate) factorial trial. 2. Egg yolk cholesterol was significantly reduced by supplementary copper (Cu) and chromium (Cr) and there was an interaction between Cu and Cr supplementation. Egg production, egg weight, eggshell strength and eggshell thickness were not influenced by Cu or Cr supplementation. 3. Serum cholesterol concentration was decreased by Cu supplementation and very low-density lipoprotein (VLDL) was reduced markedly by both Cu and Cr. On the other hand, high-density lipoprotein (HDL) was significantly increased by Cu and Cr. Interaction occurred between Cu and Cr in the VLDL and HDL parameters. Supplmentary Cu also reduced VLDL-cholesterol (VLDL-C) and enhanced HDL-cholesterol (HDL-C), while supplemental Cr had a contrary effect on these two parameters. 4. If minimum egg cholesterol content is the criterion, this study suggests that 125 mg/kg of Cu together with 800 to 1600 microg/kg of Cr provide adequate supplementary concentrations for laying hens.     

蛋鸡血浆甘油三酯与蛋黄性状关系的研究

本实验对蛋鸡血浆甘油三酯 (Triglyceriche ,TG)浓度进行高、低选择之后 ,测定了两个世代的产蛋早期的褐壳鸡的血脂成分 (血浆中胆固醇、磷酯、游离脂肪酸 )及其鸡的蛋黄性状 (蛋黄比例、蛋黄胆固醇含量 ) ;且以父系半同胞法估计了血脂和蛋黄性状的遗传参数。研究了与鸡体脂肪代谢关系密切的血脂成分和蛋黄性状的变化规律及其之间的相互关系 ,来寻找能降低蛋黄胆固醇的新途径。结果表明 :血浆甘油三酯的变异系数较大为 5 3.5 2 % ;血浆甘油三酯、蛋黄比例和相对蛋中胆固醇含量的遗传力较高分别是 0 .2 74、0 .90 2、0 .30 4 ,它们之间的遗传相关分别是 0 .2 71、0 .36 6。即血浆甘油三酯可以作为间接选择蛋中胆固醇含量的指标。     

Comparison between wheat, triticale, rye, soyabean oil and strain of laying bird on the production, and cholesterol and fatty acid contents of eggs.

1. The effects of feeding three types of cereal grain (wheat, triticale or rye) and soyabean oil (0 or 20 g/kg) over a 12-week period on the production, yolk cholesterol and yolk fatty acid concentrations of three strains of laying pullets were studied. 2. Pullets fed on wheat- or triticale-based diets had higher body weight gains, egg productions, egg weights, egg mass and lower yolk cholesterol concentrations than pullets fed on rye-based diets. However, there were no significant differences between the cereals in yolk cholesterol content. 3. There were no significant differences between the three cereals in total food consumption of pullets nor of yolk weight nor yolk concentration of palmitic, stearic and oleic acids. 4. Pullets fed on triticale-based diets had higher yolk linoleic acid concentrations and lower yolk oleic acid: linoleic acid ratios than pullets fed on rye- or wheat-based diets. 5. Soyabean oil supplementation increased egg production, egg mass, yolk linoleic concentration and yolk unsaturated to saturated fatty acid ratio, but reduced yolk oleic acid: linoleic acid ratio. 6. There were differences between strains of pullets in weight gain, food consumption, rate of lay, egg weight and yolk cholesterol, but not in yolk fatty acid concentrations. 7. It was concluded that wheat- or triticale-based diets gave good production of eggs of lower cholesterol content, that soyabean oil supplementation gave eggs with a high unsaturated to saturated fatty acid ratio and that two strains of layers produced eggs with lower yolk cholesterol concentrations than a third strain.     

Correlations between breeder age, egg cholesterol content, blood cholesterol level and hatchability of broiler breeders

1. The research was carried out to investigate correlations between breeder age, egg cholesterol content, blood cholesterol level and hatchability of broiler breeders. 2. Egg cholesterol content increased with increased breeder age. The mean yolk cholesterol contents (mg per g yolk) were 10.47+/-0.28, 15.34+/-0.65 and 15.64+/-0.71 mg/g at 28, 45 and 65 weeks of age, respectively. 3. There were positive correlations between yolk weight and yolk cholesterol content (mg/g yolk) (r=01.941; P<0.01) and egg cholesterol content (mg/egg) (r=0.980; P<0.01). 4. Negative correlations were found between egg yolk cholesterol content and hatchability of fertile eggs (r=-0.345; P<0.05), fertility ratio (r=-0.609; P<0.01) and hatchability of total eggs (r=-0.574; P<0.01). 5. The mean blood cholesterol levels were 165.1+/-11.04, 166.5+/-11.97 and 179.5+/-11.33 mg/dl at 28, 45 and 65 weeks of age, respectively.     

A rapid determination of cholesterol in egg yolks using the Bio-La-Test

A technique of direct one-stage determination of the total cholesterol content in egg yolk is proposed. Yolk samples are treated by dilution into a form suitable for a diagnostic application of the Bio-La-Test Cholesterol (manufacturer Lachema, n.e., Brno, CSSR), designed for the determination of cholesterol in blood serum. The procedure of applying the bio-assay was partly modified. Modification of the Bio-La-Test for egg yolk provides results with a methodical error of 1.5%. The time needed for sample preparation and the analysis itself does not exceed 40 minutes. It was found out by checking the proposed analytical procedure that in the egg yolk of the Hisex laying hybrid the content of cholesterol fluctuated from 1.14 to 1.41 weight percent during the laying period.     

菊苣提取物对蛋鸡鸡蛋胆固醇、肠道菌群和生产性能的影响

本文旨在研究菊苣提取物对蛋鸡生产性能、鸡蛋品质、肠道菌群、血清胆同醇和卵黄胆同醇的影响.300只尼克红蛋鸡随机分为5组,每组6个重复,每个重复10只,各组日粮中分别添加0、0.5%、1.0%、1.5%的菊苣提取物和1.0%的菊粉,试验进行4周.结果表明:与对照相比,不同水平的菊苣提取物或菊粉对蛋鸡产蛋率、蛋重、采食量、料蛋比、破蛋率、蛋黄重、蛋壳厚度和哈氏单位没有显著影响(P>0.05),但能显著降低鸡蛋胆固醇浓度(mg/g蛋黄)和含量(mg/蛋黄)(P<0.05),1.5%菊苣提取物添加组的动脉粥样硬化指数显著降低(P<0.05);日粮添加菊苣提取物或菊粉显著降低蛋鸡盲肠大肠杆菌数量和pH(P<0.05),1.5%菊苣提取物添加组和菊粉添加组显著增加盲肠双歧杆菌数量(P<0.05);鸡蛋胆固醇含量和盲肠大肠杆菌数量随菊苣提取物添加水平的增加线性降低(r=-0.957和r=-0.977)(P<0.05).结论:本试验在蛋鸡日粮中添加菊苣提取物或菊粉能显著降低鸡蛋胆固醇和盲肠有害菌(大肠杆菌)的数量,且不影响蛋鸡生产性能和鸡蛋品质.故在蛋鸡日粮中添加菊苣提取物或菊粉可为生产低胆同醇鸡蛋提供一条途径.     

Hypocholesterolemic effect of karaya saponin in Japanese laying quails (Coturnix coturnix japonica)

The effect of karaya saponin supplementation on the serum and egg yolk cholesterol and fatty acid composition in egg yolk were investigated in Japanese quails. A total of 80 Japanese quails aged 5 weeks were equally divided into four groups of 20. Four levels (0, 25, 50 and 75 mg/kg feed) of karaya saponin were included in the basal diet and experiment was lasted for 6 weeks. The cholesterol fractions in the egg yolk and serum were measured by enzymatic assay, and the fatty acid composition in egg yolk was determined by gas chromatography. The results revealed that the supplementation of 75 mg/kg karaya saponin significantly reduced (p < 0.05) cholesterol and triglycerides concentration in serum and egg yolk. High-density lipoprotein-cholesterol was increased, low-density lipoprotein-cholesterol and the atherogenic index were decreased (p < 0.05) by the dietary supplementations. Hepatic cholesterol was reduced (p < 0.05) by the 25 mg/kg karaya saponin. A higher degree of yolk colour was improved (p < 0.05) when 75 mg/kg saponin was supplemented in the diet. The concentration of polyunsaturated fatty acids (PUFA) in egg yolk was increased (p < 0.05) in a dose-dependent manner in quails fed the supplemented diet than the control diet. The ratio of PUFA to saturated fatty acids in egg yolk was improved (p < 0.05) by 75 mg/kg feed karaya saponin-supplemented diet. Therefore, the dietary supplementation of 75 mg/kg karaya saponin may be a feasible means of producing quail eggs with lower cholesterol and higher PUFA content for health conscious consumers.     

Lipid profile in eggs of Araucana hens compared with Lohmann Selected Leghorn and ISA Brown hens given diets with different fat sources

1. In a cross-over trial, the egg cholesterol and fatty acid composition of Araucana hens was compared with those of two commercial breeds (Lohmann Selected Leghorn and ISA Brown) under two feeding regimes, either high (Hn-3) or low (Ln-3) in long-chain n-3 fatty acids. 2. The Hn-3 diet was formed by isocaloric substitution of animal fat in the control diet (Ln-3) by a dry product containing stabilised fish oil with standardised concentrations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). 3. Both breed and diet had influences on egg composition, without interactions. 4. The Araucana breed showed lower feed intake and lower egg weights than the other two breeds. The yolk weight was similar, leading to a much higher yolk:albumen ratio in the Araucana eggs. 5. In comparison to commercial breeds, Araucanas produced eggs with higher cholesterol content per g of yolk, which was even more pronounced when expressed per g of egg, due to the high yolk content of the eggs. The cholesterol content of an egg remained unchanged by the diet, irrespective of the dietary fat source. 6. Changing to the Hn-3 diet led to greater concentrations of polyunsaturated fatty acids (PUFA) and lower concentrations of monounsaturated fatty acids (MUFA) contents in the yolk, without a change in the ratio of saturated (SFA) to unsaturated fatty acids (UFA). 7. Within the PUFA, the n-3 fatty acids increased at the expense of the n-6 fatty acids, indicating a competition between n-3 and n-6 fatty acids for incorporation in the yolk.