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反式脂肪酸降低乳脂合成的机理 总被引:3,自引:0,他引:3
乳中的反式脂肪酸直接来源于日粮脂肪或由瘤胃微生物氢化生成,本文重点介绍了反10-油酸和反10,顺12-共轭亚油酸两种不同反式脂肪酸对乳脂合成的影响,讨论了反式脂肪酸影响乳脂合成的机理,可能是反式脂肪酸通过抑制乳腺中脂肪酸合成的关键酶乙酰辅酶A羧化酶和脂肪酸合成酶的活性,进而导致乳脂合成的减少。 相似文献
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乳脂肪受日粮因素的调控的可塑性大,CLA是乳脂肪中的一种微量不饱和脂肪酸,影响乳脂肪的物理和生物学特性。CLA最初发现于奶牛瘤胃,但牛奶中CLA主要通过乳腺组织Δ9去饱和酶作用于trans11C18∶1而内源合成。研究结果表明,日粮因素、动物个体间的差异和动物组织间SCD酶活性的差异是影响乳脂CLA合成的关键因素。作者针对影响trans11C18∶1和Δ9去饱和酶的因素对CLA合成调控因素作了简要论述。 相似文献
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乳脂肪是高质量的天然脂肪,其可为人类提供营养和能量,在各种膳食脂肪和油类中,是最容易被消化吸收的。乳脂肪是在乳腺中由从头合成或外源摄取的脂肪酸与甘油酯化形成的一种脂类物质,其含量的高低关系着牛奶品质的优劣和乳制品的加工特性。在奶牛的泌乳周期中,乳腺泌乳功能受多种因素影响,其中内分泌腺分泌的多种激素对奶牛乳腺上皮细胞(BMECs)乳脂的合成具有积极的调控作用。综上所述,作者介绍了氢化可的松、催乳素、胰岛素和生长激素4种泌乳相关激素对BMECs乳脂肪合成的调控机理,即从乳脂合成适宜的激素添加量、激素对乳脂球形态的影响方面初步阐释其调控作用,并从乳脂合成的关键酶及转录因子、激素对乳脂合成相关基因表达量方面深入阐释其作用机理,旨在为研究泌乳相关激素对奶牛乳腺内乳脂肪合成的调控机理提供参考。 相似文献
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五、日粮脂肪含量 对奶成分影响最大的是由日粮脂肪和碳水化合物的结构引起,在正常范围内日粮的蛋白质不起作用。等能日粮增加脂肪可提高乳脂率。日粮的脂肪酸向乳脂的转化依赖于脂肪酸在日粮的含量,泌乳阶段和糖元营养的摄入影响乳脂率和脂肪组织的代谢平衡。 相似文献
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在特定的日粮条件下,瘤胃氢化过程可以产生一些抑制乳脂合成的特殊脂肪酸。其中trans10,cis12CLA最早被证实能够抑制乳脂合成,而其它脂肪酸也可能是日粮诱导的乳脂降低综合症(MFD)的原因。通过气相和液相色谱技术分析显示,日粮引起MFD的同时,乳脂trans9,cis11CLA含量的升高与乳脂降低相一致。因此本试验通过使用富含9和11位共轭双键的CLA来进一步研究trans9,cis11CLA对乳脂合成的影响。选用4头安装瘤胃瘘管的荷斯坦奶牛采用4×4拉丁方试验设计。试验处理为:连续5 d皱胃灌注①乙醇;②9,11CLA混合物(其中trans9,cis11CLA占32%,cis9,trans11CLA占29%以及trans9,trans11CLA占17%);③trans9,trans11CLA;④trans10,cis12CLA。其中trans9,trans11CLA和trans10,cis12CLA纯度均高于90%,且每天灌注量为5 g,灌注速率一致。结果表明,不同处理之间产奶量和干物质采食量均无显著差异。与对照组相比,9,11CLA混合物和trans10,cis12CLA处理组乳脂产量分别降低15%和27%。而trans9,trans11CLA处理对乳脂产量没有影响,这与以前研究灌注cis9,trans11 CLA取得的结果一致。试验结果表明:trans9,cis11 CLA是第9和第11位CLA混合物中主要引起乳脂降低的异构体,但trans9,cis11 CLA抑制乳脂合成的效果低于trans10,cis12CLA。有趣的是trans9,trans11CLA降低了乳脂去饱和酶指数,这进一步说明乳脂合成过程中脂肪去饱和现象的变化是相对独立与MFD无关。试验中,当每天皱胃灌注含5 g trans9,cis11CLA后可引起乳脂降低达15%,因此,本研究证实了特定日粮条件下trans9,cis11CLA含量的增加与MFD出现存在一定的相关性,也提供了trans9,cis11CLA异构体在MFD中发挥作用的证据。 相似文献
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M.A.S. Gama P.C. Garnsworthy J.M. Griinari P.R. Leme P.H.M. Rodrigues L.W.O. Souza D.P.D. Lanna 《Livestock Science》2008,115(2-3):319-331
This experiment was designed to examine changes in milk fatty acids during fish oil-induced milk fat depression (MFD) and to test the theory that these changes are related to milk fat fluidity. The experiment was divided into three periods: 1) Baseline: all cows (n = 12) received a high fiber diet without fish oil (FO) for 12 days; 2) Treatment: 4 cows/group received the following treatments for 21 days: a) Low fiber diet without FO (LF), b) High fiber diet + FO (HF + FO) and c) Low fiber diet + FO (LF + FO); 3) Post-treatment: cows returned to the baseline diet and were monitored for 12 days. FO was included at 1.6% DM and HF and LF diets had 40 and 26% NDF, respectively. Milk fat content and yield were unchanged by the LF diet, but were reduced by FO diets at both dietary fiber levels and recovered in the post-treatment period. FO diets caused a pronounced reduction in stearic and oleic acid concentrations in milk fat and an equally pronounced increase in trans-18:1 fatty acid concentrations. Milk fat mean melting point (MMP) was correlated with MFD (r = 0.73) and with milk oleic acid concentration (r = − 0.92). The ratio of oleic:stearic in milk fat increased gradually and consistently in response to FO. Trans-C18:1 isomers with double bounds at carbon ≤ 10 increased with greater MFD and those with double bonds at carbon ≥ 11 decreased with greater MFD. Trans-9 cis-11 CLA explained more than 80% of MFD and was strongly correlated with trans-10 C18:1. Maintenance of MMP below 39–40 °C suggests that the mammary gland was able to secrete only milk fat with adequate fluidity and that MFD could be an adaptation mechanism to prevent secretion of milk with higher MMP. 相似文献
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Milk fatty acid composition is determined by several factors including diet. The milk fatty acid profile of dairy cows is low in polyunsaturated fatty acids, especially those of the n-3 series. Efforts to change and influence fatty acid profile with longer chain polyunsaturated fatty acids have proven challenging. Several barriers prevent easy transfer of dietary polyunsaturated fatty acids to milk fat including rumen biohydrogenation and fatty acid esterification. The potential for cellular uptake and differences in fatty acid incorporation into milk fat might also have an effect, though this has received less research effort. Given physiological impediments to enriching milk fat with polyunsaturated fatty acids, manipulating the genome of the cow might provide a greater increase than diet alone, but this too may be challenged by the physiology of the cow. 相似文献
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《畜牧与生物技术杂志(英文版)》2016,(3)
Milk fatty acid composition is determined by several factors including diet. The milk fatty acid profile of dairy cows is low in polyunsaturated fatty acids, especially those of the n-3 series. Efforts to change and influence fatty acid profile with longer chain polyunsaturated fatty acids have proven challenging. Several barriers prevent easy transfer of dietary polyunsaturated fatty acids to milk fat including rumen biohydrogenation and fatty acid esterification. The potential for cellular uptake and differences in fatty acid incorporation into milk fat might also have an effect, though this has received less research effort. Given physiological impediments to enriching milk fat with polyunsaturated fatty acids, manipulating the genome of the cow might provide a greater increase than diet alone, but this too may be challenged by the physiology of the cow. 相似文献
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本试验研究了阴外动脉灌注乳脂前体物对奶牛产奶量及乳腺内短链脂肪酸摄取规律的影响。选择8头健康荷斯坦奶牛分为2组,每组4头牛。采用2×2交叉试验设计,2组分别饲喂2种不同粗饲料[苜蓿(MF组)、玉米秸秆(CS组)]的饲粮,饲粮的精粗比为45∶55。试验分为2阶段,每阶段20 d,其中预试期14 d,载体灌注期3 d,乳脂前体物灌注期3 d。在载体灌注期,MF组与CS组均接受载体灌注,分别命名为MFC_1组和CSC组;在乳脂前体物灌注期,MF组继续接受载体灌注(MFC_2组),CS组灌注乳脂前体物(CSF组)。测定产奶量、干物质采食量及乳成分。采集尾动脉和乳静脉血浆测定短链脂肪酸浓度和脂肪酸比例。结果表明:1)在灌注乳脂前体物前,CSC组产奶量、4%乳脂校正乳产量、乳脂产量、乳蛋白产量和产乳脂效率显著低于MFC_1组(P0.05),CSC组尾动脉血浆中短链脂肪酸浓度及短链脂肪酸/长链脂肪酸有低于MFC_1组的趋势(0.05≤P0.10)。2)灌注乳脂前体物后,CSF组产乳脂效率和乳蛋白率显著高于CSC组(P0.05),CSF组产奶量、4%乳脂校正乳产量、乳脂率和乳蛋白率尽管在数值上仍然低于MFC_2组,但组间差异不显著(P0.05),而CSF组产乳脂效率显著高于MFC_2组(P0.05)。3)灌注乳脂前体物后,CSF组尾动脉血浆中乙酸、丙酸以及短链脂肪酸浓度显著高于CSC组(P0.05),且乙酸、丁酸及短链脂肪酸浓度显著高于MFC_2组(P0.05),短链脂肪酸/长链脂肪酸有低于MFC_2组的趋势(0.05≤P0.10)。4)除CSF组丁酸动静脉差有高于CSC组的趋势(0.05≤P0.10)外,CSC组与MFC_1组、CSC组与CSF组、CSF组与MFC_2组乳腺对乙酸、丙酸、丁酸、短链脂肪酸的摄取量、摄取率和动静脉差均无显著差异(P0.05)。结果提示,以玉米秸秆为粗饲料奶牛灌注乳脂前体物可显著增加奶牛的产奶量、乳脂率和乳脂产量,并达到与以苜蓿等为粗饲料相似的水平,且具有较高的产乳脂效率,但对乳腺内短链脂肪酸的摄取量和摄取率无显著的影响。 相似文献
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为研究不同乳脂率德宏奶水牛乳腺组织中FATP1基因的表达情况,试验选取216头处于泌乳盛期的健康德宏奶水牛,分为高乳脂率组(H组)、中乳脂率组(M组)和低乳脂率组(L组),采集乳样,用乳品分析仪测定乳脂率,利用气相色谱法测定脂肪酸含量。采集乳腺组织,利用荧光定量PCR法检测FATP1基因的mRNA表达水平,并与乳脂率和脂肪酸含量进行相关性分析。结果表明:H组乳脂率、总脂肪酸含量和长链脂肪酸含量均极显著高于M组和L组(P<0.01),M组显著高于L组(P<0.05)。不饱和脂肪酸含量H组极显著高于L组(P<0.01),显著高于M组(P<0.05),而M组与L组无显著差异(P>0.05)。FATP1基因mRNA表达水平为H组极显著高于L组(P<0.01),而H组与M组、M组与L组均无显著差异(P>0.05)。相关性分析表明,乳脂率与乳中总脂肪酸、长链脂肪酸和不饱和脂肪酸含量间呈极显著正相关(P<0.01),FATP1基因mRNA表达量与乳脂率、脂肪酸总量、长链脂肪酸含量、不饱和脂肪酸含量均呈极显著正相关(P<0.01)。研究表明在乳脂合成的过程当中FATP1基因对脂肪酸的摄取和转运起到重要的调控作用。 相似文献
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GAO San-si SHEN Tai-yu YU Hong-jiang ZHU Kui-ling ZHANG Zi-yang HUANG Bao-yin XU Chuang XIA Cheng 《中国畜牧兽医》2016,43(7):1805-1811
Milk fat globule membrane protein is packaged outside the fat granule during mammary gland lactating. Milk fat globule membrane has three-layered structure composed of phospholipids,sphingolipids and proteins. Milk fat globule membrane protein contains more than one hundred kinds of proteins,of which there are the most abundant of eight kinds of proteins including mucin 1,xanthine oxidoreductase,mucin 15,CD36,butyrophilin,lactadherin,adipophilin,fatty acid binding protein .Milk fat globule membrane protein has been shown to have special value which reflects the physiological state of cow,affects the growth of calf and maternal immune as a source of nutrition and immunity for calves,and affects the human and animal's immunity regulation and physical fitness,it may be applied to treat diseases in the future. This article summaries the study of milk fat globule membrane protein in recent years aimed at describing the source,composition of the milk fat globule membrane proteins,introducing a novel established structure of milk fat globule membrane protein,explaining the physiological characteristics of some main proteins and progress in milk fat globule membrane proteins research and making recommendations for future research directions. 相似文献