降低鸡蛋胆固醇的营养调控措施

胆固醇是细胞膜的重要组分,在维持与营养细胞膜方面起着重要作用,是人类维持正常生理活动所必需的,但人体血液中胆固醇浓度过高会引起高血脂,进而引起高血压、冠心病等一系列心血管疾病.     

鸡蛋中胆固醇含量变化规律的探讨

１材料和方法１．１试验动物试验于１９９９年３月５日～１９９９年９月１０日在郑州罗寨养殖场进行。试验动物选择２１周龄，健康，正常开产的海兰白蛋鸡１２０只，分养在３层梯形笼中，上、中、下各４０只，自动饮水；喂料、光照时间及饲养管理、防疫措施与场内大鸡群一致，试验期内喂同一种饲料（市购）。营养成分含量粗蛋白１５．２％，代谢能１１．２MJ／kg，钙３．４６％，总磷０．７％。１．２材料处理每日统计产蛋量。分别在试验的０、３、６、９、１２、１５、２２、２９、３６、５０、７１、９９、１３４、１７９d收集鸡蛋，将每…     

调控鸡蛋胆固醇含量的营养途径

禽蛋类食品营养丰富，是人们日常饮食中普遍喜欢食用的食品。蛋类蛋黄中含有大量胆固醇，胆固醇是生命活动的必需物质，适宜量的胆固醇有利于人体健康，但过量摄入可形成高脂血症，引起动脉粥样硬化，进而诱发冠心病、高血压等一系列心脑血管疾病。利用营养和分子生物学手段对蛋鸡的胆固醇代谢过程进行研究．有利于找到降低鸡蛋中胆固醇含量的措施。笔者综述了通过营养代谢调控的途径来降低鸡蛋中胆固醇含量。     

降低鸡蛋胆固醇含量的营养调控措施

鸡蛋的胆固醇和多不饱和脂肪酸（PUFA）的含量已成为衡量蛋品质的重要指标,蛋黄中胆固醇含量约占蛋黄重的4％。约为200-250mg／枚。如此高的胆固醇含量直接影响着蛋鸡养殖业的发展和蛋产品的市场容量需求。研究发现,通过营养代谢调控手段,即选用适当的方法来降低鸡蛋中胆固醇的含量,进而能生产出胆田醇含量低、多不饱和脂肪酸（PUFA）含量高的鸡蛋来满足消费者的需求。     

降低鸡蛋胆固醇含量的调控措施及其机制

鸡蛋营养价值很高,但由于含有较高浓度的胆固醇从而限制了公众对鸡蛋的消费,开发低胆固醇鸡蛋具有重要的理论价值和现实意义。通过遗传选育和在饲粮中添加脂肪（或脂肪酸）、中草药、植物甾醇、矿物质以及他汀类药物等方法能够有效地降低鸡蛋胆固醇含量。本文从遗传因素、营养因素和非营养因素 ３个方面综述了国内外学者在降低鸡蛋胆固醇领域的最新研究成果。     

降低鸡蛋中胆固醇含量的营养调控技术

本文探讨了通过营养调控技术降低鸡蛋中胆固醇含量,包括调控日粮能量、纤维素以及寡聚糖、微生态制剂、异黄酮物质、中草药、植物固醇、微量元素等营养调控剂的应用。     

鸡蛋中胆固醇含量的营养调控措施

随着人们生活水平的不断提高,其膳食结构也在不断变化,除了要求食品营养好外,开始逐渐强调绿色保健化。鸡蛋作为人们餐桌上的常见食品,胆固醇的含量日趋成为消费者和研究者关心的问题。笔者认为,通过鸡日粮营养的调控,可以一定程度的降低鸡蛋的胆固醇含量,适应社会的需求。本文     

降低鸡蛋中胆固醇含量的试验研究

胆固醇是人体健康不可缺少的营养素,但如果食入量过多,会引发动脉粥样硬化、静脉血栓、胆石症等病症,对机体产生不利影响。近年来由于人们生活水平的提高,日常膳食结构发生了很大变化,经常性的摄入动物肉类、鸡蛋以及食用油等,会导致体内胆固醇含量超标。鸡蛋含有丰富的优质蛋白、不饱和脂肪酸和微量元素,营养价值很高,但由于蛋黄中含有较多的胆固醇,限制了人们对鸡蛋的食用量,减少了优质蛋白的摄入。低胆固醇鸡蛋产品在保持鸡蛋原有营养成分的基础上降低了鸡蛋中胆固醇的含量,其营养组成有益于成人和高胆固醇血症患者食用。本试验旨在通过营养调控手段和添加饲喂益生素等措施,控制蛋鸡营养物质的摄入量或摄入能,调节蛋鸡体内脂质代谢的物质,减少胆固醇的合成和向蛋黄中的转移,可以降低鸡蛋中胆固醇含量,满足人们对低胆固醇鸡蛋的需求。     

Effect of dietary karaya saponin on serum and egg yolk cholesterol in laying hens

1. The objective of the study was to investigate the effect of dietary karaya saponin on cholesterol deposition in laying hens. 2. A total of 40 Boris Brown hens were randomly assigned at 20 weeks of age to 4 treatment groups and fed on diets supplemented with 0 (control), 25, 50 or 75 mg/kg karaya saponin for an 8-week experimental period. 3. After 8 weeks of dietary supplementation, karaya-saponin-treated groups had significantly lower serum cholesterol (23·0%) and triglycerides but increased high density lipoproteins cholesterol concentration than controls, irrespective of karaya saponin content in the diet. Egg yolk cholesterol and triglycerides were also significantly reduced by dietary karaya saponin. Hepatic cholesterol and triglycerides were significantly reduced by karaya saponin but bile acids concentration in the faeces and liver were significantly increased by karaya saponin. The concentrations of oleic, linoleic and linolenic acids in the yolk were greater in hens receiving karaya saponin than in controls. Karaya saponin significantly increased egg production, feed efficiency and yolk colour compared with controls. Karaya saponin tended to increase egg weight, feed consumption, Haugh units, albumen weight and yolk index. 4. In conclusion, karaya saponin is a potential agent for reducing yolk cholesterol concentration together with an overall increase of production performance and improvement in egg quality.     

Effects of feeding fermented fish on egg cholesterol content in hens

This study was conducted to investigate the effects of feeding fermented fish (FF) to layers on laying performance, and polyunsaturated fatty acid and cholesterol levels in eggs and plasma. A total of 96, 13-week-old Babcock B380 pullets were used in this study. They were randomly assigned to four numerically equal groups with eight replicates per treatment, three birds per replicate. All the birds were housed in individual cages. The dietary treatments were: Control diet, without FF; FF3 diet containing 3% (w/w) FF, FF6 diet containing 6% (w/w) FF and FF9 diet containing 9% (w/w) FF. The study was carried out for 16 weeks inclusive of two weeks of adjustment. Weekly feed intake and egg production were recorded. Blood plasma cholesterol and fatty acid profiles were assayed at the end of the experiment. FF did not enhance ( P  > 0.05) egg mass but ( P  < 0.05) decreased egg weight slightly. However, egg yolk cholesterol and plasma cholesterol concentrations were reduced ( P  < 0.05) by FF. The n-6:n-3 fatty acids ratio in the egg yolk (Control = 7.9, FF9 = 6.2) and plasma (Control = 10.6, FF9 = 6.2) were decreased by feeding FF. Moreover, FF was able to increase ( P  < 0.05) the docosahexaenoic acid (DHA) concentrations in egg yolk and plasma. In conclusion, this study demonstrated that FF increased DHA and reduced egg yolk cholesterol in poultry eggs.     

Effects of dietary copper on production and egg cholesterol content in laying hens

1. This experiment was carried out to determine the effects of diets supplemented with different amounts of copper on egg production, food intake, food conversion ratio, egg weight, damaged egg ratio, specific gravity, mortality and cholesterol concentration in yolk. The experiment lasted 90 d and 400 Hisex-Brown hens, aged 27 weeks at the start of the study, were used. 2. There were no statistically significant effects of supplementary copper on egg production, food intake or food conversion efficiency. 3. There were no statistically significant differences between the groups in terms of damaged eggs, egg weight, specific gravity and live weight. 4. At the end of the experiment, the lowest yolk cholesterol concentrations were obtained in the 150 kg/kg copper group and the greatest concentrations were in the control group. 5. Consequently, the use of supplementary copper to provide 150 kg/kg in poultry diets was concluded to decrease yolk cholesterol concentrations without any effect on production performance.     

Divergent selection for yolk cholesterol in laying hens

1. Lines were selected for divergence in yolk‐cholesterol concentration for three and four generations in the Cornell Control (Leghorn) and Athens‐Canadian (AC) (meat‐type) randombred populations respectively. Selection was based on both individual and family records.

2. Cholesterol values were obtained from two consecutively laid eggs when birds were 28 weeks of age. The yolks of eggs from individual hens were pooled and analysed for cholesterol content by the colorimetric assay of Zlatkis et al. (1953) on the “fat extract” obtained by a modification of the procedure of Folch et al. (1956).

3. The largest differences between high and low lines (1.lb27 and 1.lb38 mg cholesterol/g yolk) were observed in the last generation of selection. There was evidence of a lack of response in the low lines. Realised herita‐bility estimates obtained by dividing the difference between high and low lines by half the cumulative selection differential ranged from 0.lb11 to 0.lb25 in the AC population and from 0.lb21 to 0.lb25 in the Leghorn population. Realised estimates on a within‐line basis suggest that selection for yolk cholesterol is effective only in the upward direction.     

Effects of inulin on performance, egg quality, gut microflora and serum and yolk cholesterol in laying hens

1. The present study was conducted to investigate the effects of inulin on laying hens. A total of 360 Brown Nick laying hens were divided randomly into 6 groups of 60 with 6 replicates of 10 hens and fed on diets containing 0 (control), 0·1, 0·5, 1·0, 1·5 or 2·0% inulin during the 4-week trial. 2. Dietary supplementation of inulin reduced cholesterol concentration (mg/g yolk) and content (mg/egg) in eggs. Cholesterol content in eggs decreased linearly with increasing levels of dietary inulin level. 3. Supplementation of inulin in diets decreased coliform bacteria counts and pH in the caecum. The lowest coliform bacteria counts (6·30 ± 0·03 log10 cfu/g) and pH (6·47 ± 0·01) were obtained in the 2·0% inulin group, the two indices decreasing by 21·6% and 3·0% respectively, compared with the control group. Coliform bacteria count and pH were changed linearly in accordance with increasing levels of dietary inulin level. Caecal Bifidobacteria counts were increased in the 2·0%-inulin group. 4. Inulin supplementation of layer diets did not appear to have any adverse effects on laying rate, egg weight, feed intake, feed conversion efficiency, cracked-egg rate, eggshell thickness or Haugh unit compared with the control laying hens. 5. Therefore, dietary supplementation with inulin may lead to the development of low-cholesterol chicken eggs as demanded by health-conscious consumers.     

Effect of fructooligosaccharides and antibiotics on laying performance of chickens and cholesterol content of egg yolk

1. Nine hundred and sixty 25-week-old Lohmann Brown layers were randomly divided into 5 groups with 216 layers in each group. Layers in group one were fed a control diet, group 2 received the control diet plus 20 mg/kg zinc bacitracin and 4 mg/kg colistinsulfate, and the remaining three groups received control diet plus 2000, or 4000, or 6000 mg/kg fructooligosaccharide (FOS). 2. The results showed improvements in egg production, feed consumption and feed conversion of layers when 2000 mg/kg FOS was added to the diets. 3. The results also showed some additional improvements in the group supplemented with 2000 mg/kg FOS, including increases in egg shell thickness, yolk colour and Haugh unit, and decreases in yolk cholesterol concentration. 4. However, larger (excessive) doses of FOS did not improve the performance of layers.     

Effects of zinc and vitamin A supplements on plasma levels of thyroid hormones, cholesterol, glucose and egg yolk cholesterol of laying hens

The effects of zinc and vitamin A supplementation to the diet on some blood metabolites were evaluated in Hisex brown laying hens from 56 weeks to 68 weeks of age. A total of 130 birds were divided into two main groups according to vitamin A treatment (0 and 3.44 mg retinyl acetate kg(-1) feed, respectively), each consisting of 65 hens. Hens in both of the main groups were then divided into five zinc treatment groups (0, 25, 50, 100 and 200 mg zinc kg diet(-1) respectively) of 13 hens each. It was observed that plasma T4, T3 and total cholesterol levels were affected by only zinc supplementation. While 100 and 200 mg Zn kg(-1) decreased plasma T4 level compared to control value, plasma T3 level was reduced by 100 mg Zn kg(-1) compared to groups fed less Zn. Adding 50 and 200 mg Zn kg(-1) to the diet increased plasma total cholesterol level in the birds compared to other groups. Vitamin A, zinc, and their interaction did not influence the concentration of plasma high-density lipoprotein (HDL)-cholesterol, glucose and egg yolk cholesterol in laying hens.     

Effects of dietary supplementation of resveratrol on performance,egg quality,yolk cholesterol and antioxidant enzyme activity of laying hens

1. This experiment was conducted to evaluate the effects of dietary supplementation of resveratrol on laying performance, egg quality, egg yolk cholesterol and antioxidant enzyme activities of laying hens.

2. A total of 360 Beijing PINK-1 laying hens (60 weeks old) were randomly distributed among five dietary treatments, each of which included 6 replicates of 12 hens. Dietary treatments were basal diet supplemented with 0 (control), 0.5, 1.0, 2.0 and 4.0 g/kg diet resveratrol. The study lasted for 9 weeks including 1 week of adaptation and 8 weeks of the main experimental period.

3. The results indicated that dietary resveratrol significantly improved feed conversion ratios during 5–8 weeks and 1–8 weeks of the trial. Increasing dietary concentrations of the resveratrol linearly improved Haugh unit and albumen height of eggs.

4. The content of total cholesterol (TC), total triglyceride (TG), low density lipoprotein cholesterol (LDL-C), very low density lipoprotein cholesterol (VLDL-C) in serum and cholesterol in yolk was significantly decreased by dietary resveratrol, and there were significant linear correlations between these indexes and resveratrol supplemental levels.

5. Dietary resveratrol supplementation significantly improved serum Glutathione peroxidase (GSH-Px) enzyme activity and decreased serum malondialdehyde (MDA) content in groups with 2.0 and 4.0 g/kg resveratrol as compared to the control, respectively. However, supplementation of resveratrol did not affect the activity of serum superoxide dismutase (SOD).

6. It is concluded that resveratrol supplementation has a positive effect on performance, lipid-related traits and antioxidant activity of laying hens.