调控牛乳中共轭亚油酸含量的研究进展

介绍了共轭亚油酸(CLA)的来源和在人体中的生理作用,重点阐述影响牛乳中CLA含量的因素,包括在日粮中添加油脂、饲喂制度、季节变化和地理位置,提出了调控牛乳中CLA的含量的两种途径:改变日粮和饲养管理方式。     

调控牛乳中共轭亚油酸含量的研究进展

介绍了共轭亚油酸(CLA)的来源和在人体中的生理作用,重点阐述影响牛乳中CLA含量的因素,包括在日粮中添加油脂、饲喂制度、季节变化和地理位置,提出了调控牛乳中CLA的含量的两种途径改变日粮和饲养管理方式.     

日粮调控乳脂CLA含量研究进展

一系列医学研究证实共轭亚油酸（CLA）具有抗癌、抗动脉粥样硬化、抗氧化、降低脂肪沉积、促进生长以及调节免疫等重要生理活性功能。人类摄取CLA主要来源于膳食中的反刍动物制品,尤其是牛乳。因此,如何提高牛乳中CLA的累积便成为当今反刍动物营养专家们研究的重点与热点。国内外研究报道表明,乳脂中CLA含量极易受日粮影响。     

改善牛乳脂中共轭亚油酸含量的研究

自从发现共轭亚油酸特殊的生理作用以来,共轭亚油酸就一直是动物营养、药物及食品等研究领域的一个热点,目前对于含有共轭亚油酸的功能性食品的研究越来越受到关注和重视。文中阐述了现阶段改善牛乳脂中共轭亚油酸含量的各种方法和手段,为以后共轭亚油酸的深入研究提供一些参考。     

营养调控奶牛乳脂中共轭亚油酸的含量

共轭亚油酸(CLA)是一种新型的功能性脂肪酸,因其具有特殊生物学功能和营养调节作用,所以改善和提高畜产品中CLA的含量日益成为研究热点。本文介绍了一些重要的营养调控措施,以提高奶牛乳脂中CLA含量。     

杨凌地区奶牛乳中共轭亚油酸含量测定及其影响因素

随机抽取杨凌地区80头荷斯坦泌乳奶牛的240个乳样,采用紫外分光光度计检测乳样中共轭亚油酸（CLA）含量。结果表明：杨凌地区奶牛乳中共轭亚油酸含量平均为2．7±0．17（mg／g fat）;奶牛乳中共轭亚油酸含量受多种因素的影响,场地、年龄、胎次、乳脂率、产奶量等均影响乳中共轭亚油酸的含量。随着年龄、胎次的增加．共轭亚油酸含量上升,不同场地奶牛乳样中共轭亚油酸含量差异较大（P〈0．05）。     

调控牛乳中共辗亚油酸含量的研究进展

介绍了共轭亚油酸（CIA）的来源和在人体中的生理作用，重点阐述影响牛乳中CIA含量的因素，包括在日粮中添加油脂、饲喂制度、季节变化和地理位置，提出了调控牛乳中CIA的含量的两种途径：改变日粮和饲养管理方式。     

影响牛乳中共轭亚油酸(CLA)因素

随着社会人口的老龄化，恶性肿瘤已经成为一个越来越被普遍关注的重大问题，在过去的３０年中，尽管对癌症进行了广泛的研究，并在这一领域取得了显著的成绩，但患有结肠，乳腺，肺，胰腺，前列腺和膀胱的原发及转移癌患者的死亡率一直没有下降（Sporn，１９９６）。尤其肺癌、结肠癌、乳腺癌和前列腺癌占癌症死亡率的一半以上。大多数癌症是饮食和生活方式等因素的长期作用所致，其次是环境化学因素。对于癌症的外科治疗或化学治疗，预后效果多数不佳，所以，要想征服癌症不应以治疗为主。而应以预防癌症作为攻克癌症的重点。一、共轭亚油…     

牛乳脂共轭亚油酸的合成及其营养调控

共轭亚油酸(CLA)是存在于动物脂肪和乳脂中的天然活性成分。本文综述了牛乳脂CLA的来源、合成机制及其营养调控。     

牛乳脂共轭亚油酸的来源及其含量调控研究进展

共轭亚油酸（CLA）即共轭十八碳二烯酸，是亚油酸的一组构象和位置异构体，这些异构体的共同特征为2个双键直接通过1个碳-碳单键连接，没有被亚甲基隔开。在人类和动物中最主要的CLA异构体为cis-9，trans-11异构体（Chin等，1992）。近20年的研究发现CLA具有多种有益的生物学功能，包括抗癌、降低血液和肝脏胆固醇浓度、免疫调节、改善肉品质、抑制脂肪沉积，另外CLA还能降低动脉粥样硬化，减少动脉粥样硬化模型动物的主动脉中的脂肪条纹形成、促进动物生长与饲料转化效率、降低动物体脂和提高肌肉含量，牛奶和牛、羊肉等反刍动物来源的食品是最主要的CLA天然来源。     

共轭亚油酸在猪营养中的研究进展

共轭亚油酸是一种功能性脂肪酸,具有抗癌、抗动脉硬化、抗糖尿病、抗氧化、降低脂肪沉积、促进骨生成、提高免疫力和缓和狼疮等功能.作者就共轭亚油酸在猪营养中的研究进展进行了综述,并试图探讨其作用机理.     

苜蓿青贮对牛奶中共轭亚油酸含量的影响

试验采取完全随机设计,在日粮中分别用0、27%和54%的苜蓿青贮代替玉米青贮,共3种处理日粮、对30头高产奶牛乳中共轭亚油酸的含量进行了研究。采用气相色谱法分析牛乳中的共轭亚油酸含量。试验结果表明,用苜蓿青贮替代玉米青贮能有效提高牛乳中共轭亚油酸的含量。     

Biological activities of conjugated linoleic acid (CLA) and effects of CLA on animal products

Conjugated linoleic acid (CLA) is a collective term for a group of positional (c8, c10; c9, c11; c10, c12, and c11, c13) and geometric (cis,cis; cis,trans; trans,cis; and trans,trans) isomers of octadecadienoic acid (linoleic acid) with conjugated double bond system. Dietary CLA increased the ratio of saturated fatty acid (SFA) and decreased unsaturated fatty acid (USFA) in the egg yolk and CLA sources for fat improved the color stability possibly by inhibition of lipid oxidation and oxymyoglobin oxidation in beef patties. Also dietary CLA reduced purge loss in pork loin, it could be due not only to high intramuscular fat content but also to stability of cell membrane lipids assumed by the observed delay in lipid oxidation for CLA. Cholesterol content in egg yolk was significantly decreased by a supply of dietary CLA for 5 weeks feeding. Dietary CLA and storage of CLA eggs increased the firmness of hard-cooked egg yolk and the texture of yolks from hard-cooked CLA eggs was rubbery and elastic and yolk were more difficult to break using an Instron. The eggs produced by hens fed CLA were hard and were characterized by a reddish yolk when cooled to 4 °C for 10 weeks. Several studies have determined the antioxidant property of CLA. The oxidative reactions could influence CLA concentrations by either causing the formation of linoleic acid radicals, which in turn could be converted to CLA by hydrogen donors, or causing the oxidative destruction of the conjugated double-bond system of CLA.     

Enrichment of conjugated linoleic acid (CLA) in hen eggs and broiler chickens meat by lactic acid bacteria

1. The aim of this work was to compare conjugated linoleic acid (CLA) concentrations in chickens supplemented with 4 American Tissue Culture Collection (ATCC) bacterial strains, Lactobacillus plantarum, Lactobacillus lactis, Lactobacillus casei and Lactobacillus fermentum, and 4 isolates of Lactobacillus reuteri from camel, cattle, sheep and goat rumen extracts.

2. Micro-organisms were grown anaerobically in MRS broth, and 10⁶ CFU/ml of bacteria were administered orally to mixed-sex, 1-d-old broiler chickens weekly for 4 weeks and to 23-week-old layer hens weekly for 6 weeks.

3. The 4 strains were evaluated for their effects on synthesis of CLA in hen eggs and broiler meat cuts.

4. Administration of pure Lactobacillus and isolated L. reuteri strains from camel, cattle, goat and sheep led to significantly increased CLA concentrations of 0.2–1.2 mg/g of fat in eggs and 0.3–1.88 mg/g of fat in broiler chicken flesh homogenates of leg, thigh and breast.

5. These data demonstrate that lactic acid bacteria of animal origin (L. reuteri) significantly enhanced CLA synthesis in both eggs and broiler meat cuts.     

Effect of dietary conjugated linoleic acid (CLA) on broiler performance, serum lipoprotein content, muscle fatty acid composition and meat quality during refrigerated storage

1. A trial was conducted to investigate the effects of dietary conjugated linoleic acid (CLA) concentration on performance parameters, carcase composition, thiobarbituric acid reactive substances (TBARS) and fatty acid composition in leg and breast muscle and serum lipoprotein concentrations. 2. A total of 128 male chickens were allocated to 4 dietary treatments (0, 1, 2 and 3% CLA) and given a standard starter diet from d 1 to d 21 and a finisher diet from d 22 to d 42. Breast and leg muscles were stored at 4 degrees C for 1, 3 or 7 d. Fatty acid composition, TBARS and pH were determined in muscles. 3. Weight gain and feed conversion ratio were positively influenced by dietary CLA level. CLA isomer concentration in muscles increased linearly (P < 0.01) as dietary CLA increased. Addition of CLA to feeds significantly increased saturated fatty acid (SFA) and polyunsaturated fatty acid (PUFA) and decreased (P < 0.01) monounsaturated fatty acid (MUFA) in leg and breast tissues. 4. Muscle pH decreased with duration of refrigerated storage. TBARS values were significantly (P < 0.01) influenced by dietary CLA and storage time. CLA increased total cholesterol, LDL-cholesterol and HDL-cholesterol, but reduced triglycerides in the plasma of broilers.     

Milk production, milk fatty acid composition and conjugated linoleic acid (CLA) content in dairy ewes raised on feedlot or grazing pasture

To evaluate milk production and milk fatty acid (FA) composition and conjugated linoleic acid (CLA) content, 75 Sicilo-Sarde ewes were used on three dietary treatments during 89 days. Two groups were conducted on rotational grazing in separate pastures of green barley grass (GB group) or perennial ryegrass (RG group) and receiving daily 300 g of concentrate/ewe. A third group was conducted in feedlot (FL group) on oat hay and silage and receiving 500 g of the same concentrate per ewe per day. Milk production did not differ among GB and RG pasture treatments (617 ml/day) but it was higher (p < 0.01) than FL one (363 ml/day). Milk fat and protein content were higher for ewes in FL than for ewes raised on both pasture treatments (88.8 and 56.7 vs. 74.5 and 54 g/kg for fat and protein, respectively). However, fat and protein yields were higher for pasture groups than FL one. The palmitic, oleic, miristic, stearic, and caprinic acids were dominant for all regimens. Short-chain FA (C4:0–C10:0) did not differ among all treatments. The medium chain FA content was significantly higher in milk fat from FL group. Conversely, the long chain ones increased for grazing groups. Milk from pasture groups had a higher C18:3 proportion than that from FL sheep (4.5 vs. 2.7 g/1000 g). The CLA content was significantly (p < 0.001) higher for grazing groups than for FL one (7.3 and 10.3 for GB and RG, respectively, vs. 2.4 g/1000 g for FL). Pasture-based diets increased the concentrations of long-chain unsaturated FA and desirable FA in milk fat.     

高含量共轭亚油酸豆油饲喂蛋鸡试验

选择900羽海兰灰商品蛋鸡,随机分为2个处理,每处理3个重复,每重复150羽鸡,研究在日粮中添加0和1.0%共轭亚油酸对蛋鸡生产性能及饲养效益的影响,以验证自行研制的高含量共轭亚油酸豆油在蛋鸡中的作用及在蛋鸡生产中应用的可行性,试验期60d。结果表明,尽管试验组产蛋率和蛋质量分别降低了0.62%和0.76%,每千克产蛋饲料成本提高了7.97%,但每羽蛋鸡所获毛利润比对照组高10.58元,提高率达256.8%。结果表明,在蛋鸡饲料中添加高含量共轭亚油酸豆油具有提高经济效益的作用,因而在生产中推广应用是切实可行的。     

Effect of dietary vitamin A restriction on marbling and conjugated linoleic acid content in Holstein steers

To determine the effect of duration of dietary vitamin A restriction on site of fat deposition in growing cattle, 60 Holstein steers (BW = 218.4 +/- 6.55 kg) were fed a diet based on high-moisture corn, with 2,200 IU of supplemental vitamin A/kg of DM (control) or no supplemental vitamin A for a long (243 d; LR) or short (131 d; SR) restriction before slaughter at 243 d. The SR steers were fed the control diet for the first 112 d. Steers were penned individually and fed for ad libitum intake. Jugular vein blood samples for serum retinol analysis were collected on d 1, 112, and 243. Carcass samples were collected for composition analysis. Subcutaneous fat samples were collected for fatty acid composition. Fat samples from the i.m. and s.c. depots were collected to measure adipocyte size and density. Feedlot performance (ADG, DMI, and G:F) was not affected (P > 0.05) by vitamin A restriction. On d 243, the i.m. fat content of the LM was 33% greater (P < 0.05) for LR than for SR and control steers (5.6 vs. 3.9 and 4.2% ether extract, respectively). Depth of back-fat and KPH percentage were not affected (P = 0.44 and 0.80, respectively) by vitamin A restriction. Carcass weight, composition of edible carcass, and yield grade were similar among treatments (P > 0.10). Liver retinol (LR = 6.1, SR = 6.5, and control = 44.7 microg/g; P < 0.01) was reduced in LR and SR vs. control steers. On d 243, LR and SR steers had similar serum retinol concentrations, and these were lower (P < 0.01) than those of control steers (LR = 21.2, SR = 25.2, and control = 36.9 microg/dL). Intramuscular adipose cellularity (adipocytes/mm2 and mean adipocyte diameter) on d 112 and 243 was not affected (P > 0.10) by vitamin A restriction. Restricting vitamin A intake for 243 d increased i.m. fat percentage without affecting s.c. or visceral fat deposition, feedlot performance, or carcass weight. Restricting vitamin A intake for 131 d at the end of the finishing period appears to be insufficient to affect the site of fat deposition in Holstein steers.     

共轭亚油酸的免疫应激调控作用

<正>共轭亚油酸(CLA)是必需脂肪酸亚油酸的一组异构物的总称,由于其分子结构中2个双键被共轭连接,表现出顺式及反式两种空间构型,从而具有广泛而多样的生物学特性。近年来,共轭亚油酸在动物营养中的作用日益受到关注,并逐渐成为研究的热点。研究表明,共轭亚油酸具有营养重分配的作用,可降低机体脂肪含量,提高瘦肉率;共轭亚油酸还具有抗癌、抗动脉粥样硬化作用;低剂量的共轭亚油酸也有降低血脂和血液胆固醇的效应;另外,共轭亚油酸在不同动物模型中均表现出不同程度的免疫调控作用。